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Crop Factor: Why you multiply the aperture by the crop factor when comparing lenses
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- Опубліковано 16 сер 2024
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This video has serious errors and should be taken down. It's really an embarrassment to the channel.
Tony & Chelsea Northrup thank you for revealing this matter. I love this topic it really helps me in choosing lens.. I want to buy your stunning photography, please tell me how can get the coupon code. Thank you.
The explanation is totally wrong and misleading.
@@xiaodisunzhou8496 I agree! People should look at this explanation instead: ua-cam.com/video/ZUbU6exONdU/v-deo.html
I’m thinking of getting your books now. This video was well explained. If now only people could listen what was actually said and what was not.
This comment section is like comedy. Really, really sad comedy.
So in short, just so people don't misunderstand this - you're actually talking about the the effective DoF, not the actual amount of light coming through the lens. Logically, an f/2.8 on a full-frame is still a f/2.8 on a m43-camera, however the effective depth of field is equivalent of a f/5.6. This has to do with the size of the sensor, as you very well explained.
Great explanation, just some bits and pieces that could've been misunderstood.
The amount of light hitting the sensor is 4 times less as well. You would need an F/1.4 lens to compensate for the total light and DoF.
That's right, it's why full frame is always better at low light and less noise for this reason.
With plenty of light in a scene the FF will have less noise.
With low light in a scene and the same amount of light on both sensors they will have the same amount of noise. I have never seen proof against this fact.
Are you saying a 5D and an 80D with same aperture/shutter and iso setting will exhibit the exact same noise in an image?
oo0Spyder0oo Considering that the 5D is so old the 5D will be marginally better. This test is unfair to the 80D because it's receiving 2 times less light.
NO ONE else has ever mentioned this in any video I've ever seen.
It's cause people are in denial about this it seems.
or because if you study at least a little bit of the physics you would get that already, but hey, let's just watch youtube videos
Jagh Haringenamn Yes, it is confusing because the aperture does not change at all, the Northrups are just offering A WAY OF COMPARING depth-of field results on different sized sensors. THE APERTURE IS WHATEVER IT SAYS ON THE LENS...that's how much light it will transmit, so there is no need to worry about your exposure settings. If you think about it, the light level is the same at the centre of the image cast by the lens as it is at the edges of the image. Even if it was a tiny little sensor from a cellphone, the light level would be the same.
Iacuzzi is your degree from the university of snobby UA-cam commenters? 🤣
because this is simply not true. it would only be true if the crop sensor would be the exact same sensor technology as the full frame sensor. this guy's theory entirely ignores this. it is so easy to disprove. a sony a7r ii has two times better noise performance than a canon 5D ii yet both are full frame sensors. so according to this guy a f2 sony lens becomes f4 when you mount it to a canon 5D 2 body? nope. Equivalencies like this are totally useless because different companies use different technology for their sensors signal processing, this is why the newest m43 camera's sensor has better noise performance than canon aps-c cameras. We have to accept that different sensors will behave different way and use the depth of field equivalency only because that is useful, the exposure equivalency is useless. And another thing: if there is plenty of light, the noise difference will be unnoticable anyway- in daylight the crop sensor's noise level will be below the noticeable limit just like the larger sensors noise level. I can see why he uses it but it simply doesn't hold in all situations so he shouldn't spread it as a fact.
You are absolutely right. Simply because, if you are wrong, my note 4 rear camera with f2.2, would be better than canon 70-200 f2.8. Which is wrong because we have to multiply this with the crop factor of the tiny sensor of note 4 camera, and it will become above f11
I watched this video and then spent a few weeks reading online articles and thinking about it. The conclusion is that I agree with what he says in this video.
You shouldn't.
FOV radius at any given working distance is not linear, while DOF with regard to working working distance is.
Anyone who has spent any time using a camera should intuitively realize this.
What this means in practice isfilm plane
This means that any compensation for depth of field will not necessarily double the projection of magnification, so moving in closer won't necessarily compensate depth of field for crop factor. This disparity naturally will decrease with focal length as FOV approaches zero degrees, and is why between 100mm and 200mm the difference in the two images is negligible. However, the same is not true of wider lenses as the FOV approaches 180 degrees (as it is applied to rectilinear lenses).
i've been lied to all these years. I've been at f/4.48 instead of f/2.8 this whole time. Wow. this is actually eye opening, never heard anyone mention this before
You've been mislead again, actually:
FOV radius at any given working distance is not linear, while DOF with regard to working working distance is.
Anyone who has spent any time using a camera should intuitively realize this.
What this means in practice isfilm plane
This means that any compensation for depth of field will not necessarily double the projection of magnification, so moving in closer won't necessarily compensate depth of field for crop factor. This disparity naturally will decrease with focal length as FOV approaches zero degrees, and is why between 100mm and 200mm the difference in the two images is negligible. However, the same is not true of wider lenses as the FOV approaches 180 degrees (as it is applied to rectilinear lenses).
@@thetwinkleturnip godamn. such a big response to a comment I made 4 years ago! LOL. appreciate you clearing it up :)
@@riyazes My take on this:
Crop factor will NOT change your f stop.
You will not get more or less light.
Your bokeh will be the same.
You can think of it as just cropping down a full frame sensor in photoshop
The 'equivalent focal length' is just a way for us to imagine how different focal lengths will look across sensors.
@@riyazes Get mind blown!!
@@fatboyslimz2554 haha. 4 years later still mind blown LOL
You made some good points most people fail to make!
Unfortunately, he's not correct and it is just tragic how many people have been mislead by this - FOV radius at any given working distance is not linear, while DOF with regard to working working distance is.
Anyone who has spent any time using a camera should intuitively realize this.
What this means in practice isfilm plane
This means that any compensation for depth of field will not necessarily double the projection of magnification, so moving in closer won't necessarily compensate depth of field for crop factor. This disparity naturally will decrease with focal length as FOV approaches zero degrees, and is why between 100mm and 200mm the difference in the two images is negligible. However, the same is not true of wider lenses as the FOV approaches 180 degrees (as it is applied to rectilinear lenses).
You explained it very well! I’m a m43 user. Some people think that m43 sensor can’t do any bokeh which is not true. And it is not “harder” as there are many tiny to mid size lenses with 1.2-1.8 aperture to compensate the small sensor size. So generally speaking the image quality is not worse on m43 it depends on the lens you use. When weight, size and price don’t matter, then yes full frame has better image quality.
Chelsea - thanks for being so patient throughout the video 👍
Sensor size does NOT change DOF. However, practically, recomposing an image for the same framing of the subject by moving further away with a crop sensor or using a longer focal length (100-200mm as in this video) thus compressing subject/background, you get less bokeh with the same composition.
@C T the depth of field for lenses is the range of what’s in focus so it directly affects bokeh
And this vid shows that 100mm on a 2X crop sensor doesn’t produce the same DOF as 200mm on full frame
So what ART and BRI said was half right, if u put the same lens on a FF and APS-C camera, and cropped the FF to match the framing of the APS-C, you’d get the same amount of bokeh
FOV radius at any given working distance is not linear, while DOF with regard to working working distance is.
Anyone who has spent any time using a camera should intuitively realize this.
What this means in practice isfilm plane
This means that any compensation for depth of field will not necessarily double the projection of magnification, so moving in closer won't necessarily compensate depth of field for crop factor. This disparity naturally will decrease with focal length as FOV approaches zero degrees, and is why between 100mm and 200mm the difference in the two images is negligible. However, the same is not true of wider lenses as the FOV approaches 180 degrees (as it is applied to rectilinear lenses).
This is like saying “no one has ever died from falling, it’s the impact that kills them.” It’s technically correct but ignores the intrinsic link between the two things.
@@jomsies so if i want a ff image of a 23 f1.4 on a aps-c sensor.... im doing 23mm by f2.8? i suck at math but get the concept but im just lost with all the reading here
The formula for the depth of field is
D = s / (1 ± N × 0.03 / c × (1000 × s - f) / f²)
s: the distance (meters)
N: the aperture value
c: the crop factor
f: the focal length (mm)
The crop factor is there.
Finally! The best and only video on UA-cam which explains this completely, including the difference between background blurs. Great, thanks!
Thanks!
Correct about the bokeh, DoF and aesthetics of the image. However, Tony you are mistaken about the light transmission decreasing on a crop factor. In Physics, a lens that allows for a certain amount of light over a given area gives the SAME theoretical values over the whole surface and does NOT change if you decide to only use the central portion of the same sensor instead. You need to run the same test using the same sensor and the same lens, once in Full Frame and once in Crop mode (as I did with my Sony A7RII, for example). Then open the two images in Photoshop and sample the very same area using the Eyedropped/Color Picker (it helps using an object with homogeneous color, like a colored sheet of paper, sampling the same point, say, near a corner). If both photos (FF and crop) are taken with the same shutter speed and f number and ISO then you will find that the exposure values (RGB, Luminance, etc) are pretty much the same, which will show you that the light hitting that very portion of the sensor stays exactly the same. In fact, you get to keep the same shutter speed and the same exposure, differently from what you'd get if you decided to use a Tele-extender instead.
@andybertozzi Duh, of course exposure is the same, but the total amount of light across the whole sensor is what matters for photography. When you crop to 1.5x, you've multiplied the area of every speck of noise in your image by 1.5^2, so the cropped image is a little more than twice as noisy. This is exactly what happened if you stop down from f1.8 to f2.8 (actually more like f3.1) on a full frame camera. Hence why a cropped image looks exactly 'equivalent' to a full frame camera stopped down by 1 and 1/3rd of a stop.
We shoot with a lot of different cameras, and prior to this video I was pretty much convinced to just buy a bunch of full frame cameras because we were getting such unreliable results from shooting the same thing from different perspectives. I really appreciate this video if just because it helps me be able to consider cheaper cameras for a B or C camera and be able to do the math to at least feel like our shots should give similar results. Thanks again for all of your videos!
While I agree with most of the comments here saying it's misleading to multiply the f-stop by the cameras crop factor (this was my initial reaction to this video), Tony does make a valid point. The only thing missing in this video is a clear statement in the beginning saying that you should ONLY multiply the f-stop and crop factor when comparing the image result (mainly bokeh and effective focallength), NOT the exposure. As everyone who knows their basics in photography knows f2.8-1/125s@ISO200 will produce the exactly same exposure regardless of the size of the sensor. However the effective focallength and bokeh will be different depending on the crop factor. When Tony said the 45mm/1.8 on a 2x crop body equals a 90mm/3.6 (as opposed to a 90mm/1.8 which is the "common way" of comparing crop factors), Tony was not talking about lowlightcapability, only focallength and bokeh. I only wish Tony had stated this clearly to start of in the video, since many youtubers seem to think Tony doesn't know what he's talking about. This isn't the case though, everything he says is correct, but unfortunately easy to misunderstand since people are used to only comparing focallength and crop factor due to the fact that exposure remains unaltered comparing sensorsizes. If we explore deeper we can see the bokeh is affected by cameraformat, something most people (including me) don't take into consideration on a daily basis. Correct me if I'm wrong Tony, but I think this was the message you were trying to get out - and I find it fascinating.
Ps. Sorry for the long comment :)
Fredrik Lindberg actually not only dof is affected, but also the view angle and the background compression. so the fuji f 1.2 behaves like a full frame f.1.8 in all except exposure, which remains f1.2 ... disclaimer I have. a Fuji mirror less system so I'm not biased!!
Nicola D'Elia
Exactly, viewangle + background compression changes according to focallength. This means we agree since I wrote Tony could have stated that only the bokeh and effective focallength is different on crop sensor cameras, ergo your fuji f1.2 behaves lika a full frame f1.8 when comparing the images (with the exception of exposure which as you said remains f1.2). I never claimed only dof is affected..:)
Correct me if I am wrong but from my understanding this guy is right when it comes to the crop factor of focal length, but crop factor does not apply to aperture. At 3:05 notice how he is shooting at 200mm with the full frame camera and 100mm with the micro four thirds camera. If you increase your focal length you are going to decrease your depth of field and get a blurrier background*. Hence his comparison is not valid. For this test to be fair you would need to keep both cameras at 100mm and crop the full frame camera to have the same frame as the micro four thirds camera. If you did this you will see that the bokeh is about the same. You can actually see this at 1:21 - the background blurriness is the same from all 3 cameras.
True a 100mm MFT lens has the same field of view as a 200mm full frame lens, but it is still technically a 100mm lens. The reason you get the equivalent field of view is because of the difference in sensor size. But crop factor does not apply to aperture. Aperture is the ratio of focal length to the diameter of the iris. A MFT f1.8 lens is still a f1.8 and it can get the same amount of bokeh as a full frame f1.8 lens, but you would need to change the position of the camera. Technically you could get more bokeh on a MFT lens because you would have to move the camera closer to the subject to get the same relative frame as the full frame camera. Decreasing object distance to camera decreases depth of field = more bokeh.
*physicssoup.wordpress.com/2015/04/26/how-do-object-distance-and-focal-length-affect-depth-of-field/
I am pasting a link to a video that proves my point. It is a comparison between a MFT camera and a full frame camera with exactly the same settings. You will see that bokeh is about the same on both cameras: ua-cam.com/video/-2EoYGVblAQ/v-deo.html
he used 200mm on the full frame and 100mm on the micro four thirds because that would make them about equal focal lengths, the 4/3 being 2x crop factor. So now that they are equal in focal length, he's explaining that due to the 200mm on the full frame, the aperture for that focal length gives more blur than the 100mm does, which is right. I get more blur/better bokeh from a 100mm EF lens on my full frame than the same on my APS-C body. Yes it's not exactly applying crop to the aperture, just showing that to achieve the same blur requires different aperture settings depending on the sensor in use.
Tom, I think you made a little mistake when you wrote: "Technically you could get more bokeh on a MFT lens because you would have to move the camera closer to the subject to get the same relative frame as the full frame camera. Decreasing object distance to camera decreases depth of field = more bokeh."
Actually, when using the same focal length lens on two different sensor size cameras, to maintain the same relative subject size, you have to move twice the distance AWAY from your subject with the MFT camera vs. a Full Frame - since the field of view of the MFT appears to multiply the size of subject by a factor of two compared to a Full Frame camera. Thus, the need to double the distance between the subject and MFT camera also increases the DOF over the Full Frame (when trying to maintain the same field of view). Therefore, with any given lens, the MFT camera has less DOF and bokeh than a Full Frame camera when keeping the same relative subject size (field of view).
Randy Tesch Good point! Thanks for explaining that to me.
No problem, Tom! We are all just trying to learn new things and help each other.
rstesch.smugmug.com
Tom Hartvigsen thank you 😊
Wow, that was extra technical, and extra informative. Seriously. There are alot of crop sensor owners out there. Almost anyone that is a hobbyist DSLR shooter is using a crop sensor, and they have to shop for lenses, and they are looking for certain apertures to achieve certain effects.
This information IS TOTALLY RELEVANT to nearly every hobbyist shooter. So thanks for the breakdown!
----
Side note. Not trying to be weird, I am new to your channel, you two are a very attractive couple.
You are right on with the exception of the first sentence "You need to take the crop factor into count when you are comparing different LENSES." You , you need to take it into consideration then you compare different cameras. If you use just one body and change lenses, you can forget the crop factor.
There are people who have gotten the wrong view that EF and EF-S lenses are somehow different and with EF you need to multiply the aperture and with EF-S not. After that there is half a dozen comments saying "Northrup is wrong" , "He does not know what he is talking about " etc. :-)
I never comment on any videos, but I have to say this is the best video and best explaination I've ever seen/read regarding the relation between crop sensors and bokeh - exactly what I wanted to know for a long time! Thanks Tony, keep up with those excellent videos, very informative, very easy to understand and yet not leaving out any technical detaills just for the sake of making it easier to understand.
Cheers,
Carsten
Carsten Linke Thanks, Carten!
Finally a good explanation! I would have added 1 more thing: background compression ratios. People argue that shooting with a 400mm on a full frame gives you the same picture as a 200mm on a MFT or a 300mm APS-C but they forget that all the sensor is doing is cropping the image, not exactly ZOOMING IN! The images are not the same even if you compensate the aperture for loss of DOF. Take a picture on a FF with a 400mm lens and then with a 200mm lens of a MFT witness how the background on the FF looks way closer to the foreground that the MFT shot although the framing of the image is the same.
Also, a lot of people criticize the MFT and APS-C sensors VS Full Frames due to that less shallow DOF using the same aperture. Well, that is not necessarily a disadvantage. Imagine you are shooting a first dance at a wedding and you have a Full Frame camera. After setting the right exposure on your FF camera you get lets say 1/100s @ f/5.6 ISO 1600 and your off camera flashes at 1/8 power. If you were to use MFT, to "match" the exposure and DOF you would basically use 1/100s @ f/2.8 @ISO +/- 800 (to compensate for the 2 stops gain in aperture keeping the same shutter speed) AND your flashes could be turned down to about 1/32 power (again to compensate for the aperture). So by using MFT youre saving on flash output, getting faster recycle ratios and longer battery duration AND keeping the same DOF... maybe you can leave strobes at home and use now speedlights since you can now shot at 2.8 and get plenty DOF
! Point being, the increased DOF on MFT and APS-C can be a plus to flash photography as well.
Yes I’m replying to a half-decade old comment, but I think this is the most important thing to consider. It’s not so much that the aperture is different on a crop sensor (it’s not), but the background compression compared to full frame will give different results that mimic different aperture.
I think.
The Enthusiasm Project why does MFT have an iso of 2 stops lower compared to FF?
I'm a really slow learner. But after rewinding this video about 5 times, I finally understood. Thanks a million for posting this video Tony and Chelsea.
Thanks Tony. I appreciate you & Chelsea. You clear, informative and information packed videos are second to none. Very impressive.
Tony Northrup What you demonstrated in this video quite clearly is why it is wrong what people usually say about the crop factor, namely that the focal length of the same lens changes when used on a crop sensor camera by the crop factor.
It does not, it just means the image is cropped. But this has nothing to do with the aperture, because - contrary to what may be inferred from the video - the crop factor does not change the exposure.
I.e. if you have a correctly exposed picture on a full frame camera with say ISO 100 1/100 sec at F4 than the same exposure will be the correct one for any APS-C, micro 4/3 or even for a medium frame camera. (At least in principle, because in reality the same ISO 100 setting may mean different real ISO on different bodies, e.g. ISO 80 for FF and ISO 128 for APS-C, but that is a completely different thing.)
By changing the focal length you changed the DOF, it's so simple. Larger focal lengths mean smaller DOFs. Therefore because to get the subject to be of the same size on the image on FF and crop sensor cameras requires different focal lengths, this also results in different DOFs.
The crop factor does not change the depth of field (DOF) if you did not change the focal length and F-stop. You also demonstrated this on the photographs taken with the same 100 mm focal length on different bodies. Crop the full frame image to get only the part of it which the crop sensor camera recorded then enlarge it to the same size and you will find the DOF to be roughly the same. (Roughly because the greater pixel density on the crop sensor does increase modify the DOF.)
Apart from these remarks, I think the method to get the aperture we need to use on an FF body to get the same DOF as on a crop body at a given aperture (i.e. multiply the aperture on the crop body with the crop factor) is valid and good.
AminTheMystic No. It may look like it did, but it did not.
Two images taken with the same lens at the same focal length an FF sensor and 2/3 crop sensor will have the same perspective although the smaller sensor will only show part of the image of the larger sensor. On the other hand if on the FF sensor you change the focal length so that the area of view matches that of the the one taken with the smaller one you also change the perspective.
So yes, the subject on the FF sensor at 200mm will be of the same size as on the image taken with the sensor of a crop factor of 2, - that's the reason why people think the crop factor modifies the focal length - but the size of the other elements on the photo relative to same sized subject will be different.
AminTheMystic the difference is cropping a 100mm lens at 2.0 crop factor is not the same as 200mm FF at the same apreture. a 200mm lens will have a image that is twice as big, so will the bokeh at same apreture and same distance. cropping does not change depth of field but zoom does. the video is a bit confusing about the aperture times crop factor reasoning. you need to set the object at further distance on a crop sensor if using the same lens taking the shot meaning you are increasing depth of field as if you are using a lens with a smaller aperture. the matter of fact is the appreture does not need to be multiplyed to the crop factor because your settings will be the same to take the shot. its only the depth of field thats changing.
I think you're overthinking this... The concept of crop factor exists only to make it easier for us to compare the results we get with different sized sensors. As I mentioned in the video, crop factor doesn't impact camera settings; it impacts results.
Tony Northrup
Maybe I am to clever by half :) - still I think your video may be misleading. In fact from most of the comments I read I got the impression it was.
The crop factor is the numerical factor the focal length of a lens on a crop body must be multiplied to determine what focal length lens on a full frame body would render the main subject to be the same size as on the image taken by the crop sensor - nothing more.
What you say about the equivalent apertures that give the same DOF on both type of bodies is a good rule of thumb though.
Andreas Falco the keyword is that the sensor size changes only the field of view and nothing more. The crop factor helps to describe the field of view by adapting the focal length so that the field of view matches to the field of view what you would get on a FF body.
7:34 sure they can say that the f/2.8 is equivalent to F/8.4 DoF wise but light gathering wise its still an f/2.8 and youll still get faster shutter speeds.
Correct
Right, as I mention, crop factor (whether for focal length or aperture) isn't a factor when calculating your camera settings. The concept of crop factor exists only to compare the images that a lens is capable of creating. If you didn't apply the crop factor to the aperture, you'd get the same shutter speed and ISO, but the noise in the image would be much higher. If you do apply the crop factor to the aperture, you'd be using a lower ISO on the smaller sensor, providing noise levels more similar to that of the larger sensor.
No you don't, as with a smaller sensor you need to use lower ISO in order to prevent noise.
@@okaro6595 and so when you lower the ISO (because the sensor is smaller on a crop) to get less noise, the image is dimmer. That is why a 1.8 on a crop is only as bright as a 2.8 on a FF, when keeping the ISO to the same low noise level.
Good and well-demonstrated points. I think this is a property of the sizes of the circle of confusion for different sensor (or film) sizes: the formula uses the product of the aperture and circle of confusion.
When I was confused btw 35mm f/1.8G DX vs 50mm f/1.8G FX for my Nikon D3300, I just tested both and realized something is not right, 50mm was given under exposed image as well as not so good bokeh for which it is famous for. Ended up buying 35mm without any regrets and yes it work like a charm on DX. I always use to wonder why did 50 mm performed so bad, now after watching this video it cleared the confusion. Thanks a lot. Every time I get learn new things from you sir.
There is no aperture crop factor. This video is a perfect example of why many people think full frame cameras give them more "bokeh." The two images were taken at DIFFERENT focal lengths, so how can they be accurately compared? Of course the image with the longer focal length will have the most background blur. That is how lens physics works. A 100mm image taken on a FF and a 100mm image taken on a crop sensor will have EXACTLY the same amount of background blur. The field of view is adjusted here to get the same image which makes this whole point about aperture/background blur crop factor very misleading. A 200mm FF shot and a 100mm on crop (200mm equivalent) will not give you the same image!!!
Read sdp.io/crop if you want to understand this topic.
Tony & Chelsea Northrup can you argue?
I’m wondering if you actually watched this video, are you suggesting the examples shown are purposely edited to be misleading? They literally show the obviously different amounts of blur when compensating for field of view only (100 m4/3 vs 200 FF), and to open the aperture in the m4/3 to achieve the same field of view AND shallow depth of field from the same distance. This was very clearly shown and is absolutely correct. If you do what you’re saying with 100 mm 1.8 lenses on 2 different format cameras, yes, the depth of field would be equivalent, but the field of view will be very different (first example in the video I believe). If you do what most people wrongly say to do, “just back up,” you’re changing the framing and *angle of view* entirely, plus depth of field gets deeper the further you move away from the subject. The foreground and background will have a different relationship to each other, bringing compression into the equation. Whether that’s important in your use case or not is up to you, but the info presented in the video is 100% correct.
That is so me very useful information Tony. This clears it up all, keep up the good work, maybe one day i'll be as good as you.
Your videos on equivalence taught me a lot. I'm actually now more excited (actually wasn't even considering it before) to get a full frame someday since lenses that are F4 will suddenly feel like an F2.5 (since I'm used to crop cameras).
iDX1701 Thanks!
Don't forget that an F4 will need more time with the shutter opened to get the same exposure as your 2.8 lens (if you have one on your APS). Alternatively, you can shoot with the same shutter speed, but with higher ISO (more noise - if that compensates the benefits of higher resolution on the full frame, it's up to you). Or you can by a 2.8 zoom for your full frame, in order not to go higher at the ISO, but you are spending a lot of money. Unless you need professional quality photos, you may not need a full frame camera... Look, a Pentax K-50 (pentraprism, 100% viewfinder - where can you find that on Canon/Nikon for the same price?) with a Sigma 17-50 2.8 will do a very good job. A Sony A6000 would also be great, if only that had a decent lens! (Like a 2.8 standard zoom, not that... "power zoom" that sucks.)
I know jack crap about cameras and lens and all that good stuff, but I surely listened to this man for 3 minutes... I just subscribed. Just bought a Canon t5i with different lens adpators and so forth... Now learning
Thanks for enlightening me. I always wondered why a full frame gives out a good bokeh effect than my crop sensor body with the same lens. Makes sense now. :D
FOV radius at any given working distance is not linear, while DOF with regard to working working distance is.
Anyone who has spent any time using a camera should intuitively realize this.
What this means in practice isfilm plane
This means that any compensation for depth of field will not necessarily double the projection of magnification, so moving in closer won't necessarily compensate depth of field for crop factor. This disparity naturally will decrease with focal length as FOV approaches zero degrees, and is why between 100mm and 200mm the difference in the two images is negligible. However, the same is not true of wider lenses as the FOV approaches 180 degrees (as it is applied to rectilinear lenses).
Tony, what you said about aperture and crop factor makes so much sense to me now that I realize what I've been doing wrong. Recently I used my crop sensor camera side by side with my Daughter who has a full frame camera. She suggested that we set our apertures at f11, which I did. But my pictures were turning out much darker than her pictures so I had to lower my aperture to f7.1. I thought there might be something wrong with my lens. It turns out there isn't anything wrong with my lens. I'm just shooting with a crop sensor camera. This is why I love using youtube to find answers for my questions. Even though this video is 9 years old, the information is still relevant.
If you were both using the same aperture, shutter speed, and ISO, they should have the same level of brightness. The crop factor won’t affect your exposure. It affects the depth of field, angle of view, and image quality.
If you were seeing different exposures with exactly the same settings in the exposure triangle, it’s probably because of manufacturers playing games with their ISO values to make their images seem cleaner at a given setting. I know from experience that Fuji does that, and some others do too.
Wow! I’ve been doing photography for a year now and never knew that aperture gets multiplied by the crop factor. I’ve never shot full frame and gotten a side by side comparison BUT I have always felt like I get different results then the youtubers I watch using the same settings
hands down one of the best technical explanations on crop factor. I always had trouble explaining this to people. Now i ll just share them this video.
One of your best videos. Learned a lot. Thank you so much.
I think that is saying more about Mr. Northrop than his understanding of the subject.
FOV radius at any given working distance is not linear, while DOF with regard to working working distance is.
Anyone who has spent any time using a camera should intuitively realize this.
What this means in practice isfilm plane
This means that any compensation for depth of field will not necessarily double the projection of magnification, so moving in closer won't necessarily compensate depth of field for crop factor. This disparity naturally will decrease with focal length as FOV approaches zero degrees, and is why between 100mm and 200mm the difference in the two images is negligible. However, the same is not true of wider lenses as the FOV approaches 180 degrees (as it is applied to rectilinear lenses).
This is a really useful video, but includes an error. To get exactly the same image in the full frame as the crop sensor with 200mm versus 100mm focal length, you needed to change the ISO, which is linear, from ISO 100 on the micro 4/3 to ISO 200 on the full frame, and stop down to let half the light in which means from f/2.8 on the small sensor to f/4 on the full frame. This would result in the background blur looking virtually indistinguishable. In your example, the f/5.6 200mm image has less background blur because you stopped down by 4x instead of 2x. Aperture numbers are squared, while ISO, shutter speed, and focal length, are linear.
Thank you Tony & Chelsea, one thing is to read about it, another thing is to visualize it. Very neat to know about the ISO adjustment and compensate the aperture loss by increasing it two stops. Thanks
At 1:21 he says 'basically it looks like I used a more telephoto lens or I got closer and closer to the subject' but this is not true. It simply looks as though the image was cropped, first by 1.5x and then by 2x. This is why we call them 'crop' sensors. If he used a longer lens or got closer, the DOF would change, but the DOF remains constant in these photos. Only the FOV has changed. In other words, they are simply cropped.
Furthermore, on an Canon 7D a 100mm lens does not magically 'become' a 160mm lens. It is STILL a 100mm lens. We can only see less of the image circle that it produces. Similarly, if you were to use the same 100mm lens on a medium format camera, you would see more of the image circle. And in fact, the circle would probably not be large enough to cover the medium format sensor, but nonetheless, the 100mm lens remains a 100mm lens and only thing changing is the amount of the image circle that is picked up by the sensor, resulting in a different crop. It is very misleading to say that the 100mm lens 'becomes' a 160mm lens.
Honestly, crop factor is a completely useless bit of information for a photographer who only shoots on one sensor size consistently. If you shoot on APS-C all you need to know is how lenses behave on YOUR camera. It's completely useless to think of their 'full frame' equivalents, just like full frame shooter doesn't care what their lenses might look like on medium format or on micro 4/3 cameras. It's not relevant. It only matters when you are switching from one system to another.
Wrong... or not wrong but your missing some points: If you were to take a full frame camera and a micro 4/3's WITHOUT moving the tripod take the exact same shot with the exact same lens. Then you were to crop the finished photo on the full frame... you would have the exact shot with the exact depth of field. So there's NO need to use the 2x crop factor applied to the aperture. What you did to get the same framing with the micro 4/3's was to throw on a longer lens on the full frame... throwing on a longer lens while keeping the tripod where it is, is the same as moving closer to the subject. When you move closer to the subject, of course you get shallower depth of field. So basically, you don't need to use the crop factor applied to aperture unless you're throwing on different lenses to achieve the same result, or keeping the same lens but getting closer.
no. you can't move closer to your subject if the subject doesn't fit in the frame. the larger the sensor, the closer you can move at any given focal length, so subject distance depends on crop factor too. hence Tony is right.
+Oskar Thunberg No... with a Fullframe camera you would have to move closer to your subject to achieve similar framing thus giving you shallower DOF. If you left the cameras at the same spot, and simply cropped the full-frame... the shots would be EXACTLY the same! You are wrong and tony is misinformed.
+Charles J Gartner I totally agree and I believe Tony do to. I think you misunderstood the clip
+Oskar Thunberg Probably... or maybe tony is oversimplifying something that has many factors: Distance, Focal length, aperture, etc. My only point is, a lens always behaves the same way, cropping the sensor does only that... crop the exact same image. It's like putting masking tape on a full frame camera to crop the sensor, you're not going to get a different image, just a cropped one. The lens wont suddenly be confused and behave any differently.
+Charles J Gartner simply put: it's no secret bigger sensors give the possibility to shoot images with shallower depth of field. to get an idea of this effect, it's a good idea to apply crop factor to aperture. this does not mean the lens does anything differently because the sensor is bigger, it only means: what you can DO with the lens is effected by sensor size.
this is probably the most informative video on UA-cam about crop vs full frame sensors.
Unfortunately it's wrong.
FOV radius at any given working distance is not linear, while DOF with regard to working working distance is.
Anyone who has spent any time using a camera should intuitively realize this.
What this means in practice isfilm plane
This means that any compensation for depth of field will not necessarily double the projection of magnification, so moving in closer won't necessarily compensate depth of field for crop factor. This disparity naturally will decrease with focal length as FOV approaches zero degrees, and is why between 100mm and 200mm the difference in the two images is negligible. However, the same is not true of wider lenses as the FOV approaches 180 degrees (as it is applied to rectilinear lenses).
Tony, Useful video. To add further complexity, is the use of focal reducers, (e.g. Metabones Speed booster). I use one on my Fuji X-H1 with full frame CONTAX Zeiss lenses. The 85mm F1.4 with speed booster, shooting wide open results in depth of field of about 1" with the subject at about 10' shooting distance . With what appears to me as razor sharp in focus images. As the speed booster is correcting both focal length and aperture.
Another great tutorial. I have a collection of decades old prime Nikkor lenses from my still photography days. I plan to buy the micro 4/3 Panasonic gh4 with a speed booster that will make a nice compromise. The Metabones Speed Booster xl + gh4 will turn for example my 24mm f/2.8 Nikkor into a 31mm f/1.8. The booster actually reduces the focal length of the lens by .64, gains one and one thirds stop of light, and increases sharpness of the lens. I'm sure Tony already knows this, but throwing this out for readers who may be skeptical of bokeh potential of the m43 sensor. To arrive at the focal length multiply the 24mm by 2x for the crop factor, then multiply that number by .64x which is the focal reducing number of the speed booster.
Chelsea is the wow factor in this video. She is incredibly beautiful and patient. She never moved while Tony was making the video. Impressive on many counts.
You stabilized the image in post? Or UA-cam did it? The windows and the chairs are "dancing".
That looks like the image stabilization of the lens, and the reason why you should disable it when you're on a tripod.
Oliver O'Neill No, it was not the lens IS system, I don't know why the the camera was shaky, but the jiggle effect you see in the video was made by applying stabilization in post.
***** weird, I've gotten that same effect with IS. had to disable it for it to behave. Maybe it was just confused.
IS should always be turned off when using a tripod.
Oliver O'Neill And now I saw that Oliver already mentioned this…lol. UA-cam hiding comments… ;)
finally i found a true test and explanation of this topic,,,i got frustrated explaining people they shouldn't change the framing and field of view while doing this test,,,they compare 70 mm focal length on full frame and the same focal length on crop body (though changing the framing and field of view) and then they say ok now the bokeh is the same !! and i couldn't convince them that their test is simply wrong....thanks tony,,,awsome explanation
It is clear from the photos that as the matrix area decreases, the pictures become darker and the current lens cannot provide the resolution of the pictures (with the matrix area decreasing, the resolution of the pictures also decreases). This is very clear.
Basically, the closer you stand to your subject, the "better" the bokeh. With a crop sensor, you have to physically take steps backwards away from your subject in order to obtain the equivalent field of view to the full frame which changes depth, which changes bokeh.
Conversely, if I didn't physically take steps backwards, I would have to zoom in on the APSC camera to obtain the equivalent field of view of the full frame. The shorter the focal length, less the bokeh due to less compression.
Did I get this right? lol
Its all about F number. Even on full frame high F number will result in DoF rather then Bokeh.
Tony, this was a very simple and accurate explanation. I agree that the major manufacturers are confusing and misleading consumers in the way they state equivalence..
Thanks again.
Drew Davis Thanks, and you're welcome!
shaolin95 Can you explain how this is not accurate? I am not a photo pro by any means, so I am asking honestly.
shaolin95 tkarlmann You have missed the point. Most of the arguments against Tony's video have to do with the way people understand these topics (aperature/Fstop, focal length, 'crop sensor', equivalency, light gatherning etc).
The point is that most non-FF cameras/lenses will be marketed in terms of FF focal lengths - take the new Panasonic LX100, for example. It is a '24-75mm' lens according to marketing material, but it's clear this is FF equivalent. It is also claimed to be a '1.7-2.8' lens. So would a picture taken by the LX100 @24MM look identical to a D810 w/24MM 1.7 lens, everything else being equal? Absolutely not. But it is marketed so that you would think you're getting a 1.7-2.8 equivalent lens. To me, this is like selling a product in the US as costing "200". Everyone here would assume you mean it's 200 dollars, but in reality, the manufacturer is saying it's 200 British pounds; very deceptive.
Either be consistent with your scheme for specifications, ie, a ~12-37MM lens, F1.7-2.8 or say it's a ~24-75 F3.4-5.6 (FF eq).
I believe this is what Tony was explaining, and giving examples of what to expect as far as photo quality and DoF. All the other stuff is beside the point, and moot (open to discussion).
shaolin95 Yes, you have explained this incorrectly over and over. f-stop of an optical system is the ratio of the lens's focal length to the diameter of the entrance pupil, it is a simple equation.
So when you use crop sensor and make that FF spec'd 100mm into an effective 160mm, the ratio also changes because the entrance pupil is the same size but the focal length has increased. I'm not going to do the math but let's say it makes an 100mm f/2.8 into an 160mm f/4.
Let's put it another way and this will blow your mind since you seem to think this is about light transmission not a ratio of focal length to pupil size. If they designed a 160mm f/4 made for the 1.6x crop factor sensor size it would transmit the same amount of light per area as the 100mm f/2.8 on a full frame (or that same lens on a the 1.6x crop sensor).
Drew D the problem is that you are trying to measure 'blurriness' with raw numbers. You have to remember just like 'field of view' is a relative term, the 'blurriness' is also a relative term. When camera manufactures write F1.7 that is a totally accurate physical measurement and you can't say its 'like' F3.4. F-number is the ratio between focal length and the diameter of the aperture and it will always remain constant for a particular lens regardless of the sensor format you use it on! Technically it has nothing to do with 'blurriness'. Blurriness is just a bi-product that we happen to appreciate. Like guitar amp distortion in rock/metal music.
A superb, clear explanation and most defiantly not something everyone knows.
A great video where everything was explained very clearly and simply, looking forward to viewing the rest on your videos on channel and will definitely get a copy of both your books. Thanks for sharing your knowledge.
comment all you want, but this guy is right. He is not the only photographer proving these calculations to be correct.
Practically, if the only thing you care is background blur, he is right. But the luminosity of the lens actually means another thing, the quantity of light that comes into the lens. A micro4/3 f1.8 lens is TWICE faster than a FF f3.7, but produce the same blur. This means that from the point of view of lens quality and specs, this video is misleading.
If depth of field depends on 3 things, focal length (this is a property of the lens), aperture (this is also a property of the lens) and distance to subject, then by zooming in from 10mm to 20mm you have changed the depth of field. This has nothing to do with the camera sensor. Where this video gets confusing is that it's missing a caveat.If you want to achieve the same depth of field AND THE SAME FIELD OF VIEW, then yes, you have to do some calculations. But if you don't care about achieving the same field of view, you can absolutely achieve the same look you get on a full frame camera with the same lens on both full frame and aps-c cameras. This is where people get confused. Aperture and focal length are properties of the lens not the sensor or the camera. It still lets in the same amount of light no matter what it is attached to. Things will only change if you're trying to achieve the same field of view as a full frame.
The depth of field depends also on the sensor size but in the opposite way people think. Smaller sensors have shorter depth of field with the same focal length because the image will be magnified more.
The formula does the depth of field is:
D = s / (1 ± N × CoC / c × (1000 × s - f) / f²)
s: the distance (meters)
N: the aperture value
c: the crop factor
f: the focal length (mm)
CoC: The circle of confusion on full frame, typically 0.03 (mm).
The + gives the near limit, the - the far limit (if negative then infinity)
Hi tony & Chelsea Northup, I really appreciated this vid. It also depressed me. Simply because it means that camera manufactures could in theory produce faster lenses for the small 4/3 bodies I love. I really struggle creating my kit when I am both a video and stills shooter, I don't want to be labeled amateur with Lumix. And yet your vid alone is proof as to why I feel handicapped in the stills world.
This technical information is very useful to those of us who have very tight budgets. Thanks!
Wow that's really useful. I've looked at lots of videos and articles about mft cameras and nobody has mentioned multiply crop factor and aperture.
Because it is not true. The video is misleading. The real thing that changes is the crop factor. Luminosity of the lenses stays the same in all the systems. At parity of lens, the picture of micro4/3 are basically the same (except for noise) than FF ones, but 2x cropped.
Hi Tony,
I love your tutorials and greatly improved my photography. I have a question. I know that 35mm lens in an APS-C sensor will have an equivalent of 50mm lens in full frame.However, I read somewhere that the "framing" is equivalent of 50mm but the "compression" is still 35 mm. I'm not sure if this was discussed in your videos but can you confirm if this is true? Thanks.
I appreciat that this is an old video - but what a great demontration and explanation.
You Northrup's are a quality act - thanks.
Best and easiest to understand explanation so far! Many thanks!
I knew that what you were saying was correct on your other video, but this explained it SOO much better than I've had it explained before! Love it! Thank you!
You really do have a beautiful bride. Good on you mate!
Yeah some pukka property there. Keep up your acquisitions ;-)
I learned this in school. It is so nice having this video to refresh my memory!
Aahhh.... Had to watch it twice to get it in my head ! Really informative (as all your videos are). Makes perfect sense and its another bit of useful info to carry around !! Many thanks Tony and Chelsea!
Extremely useful video. Thanks a lot. BTW I bought the book :).
kratuna0 Thanks!
I'm slightly more confused now..
Adanna Egbe 😂😂
pay no attention to this. it's rubbish. Basically what's going on is this:
Lenses focus light into discreet "packets" called the "Circles of Confusion", or "CoF". When you look at OOF portion of an image, these circles are sufficiently large that they read as being "blurry". That is the reason why you get "bokeh balls" through things like leaves.
So when we're talking about sharp focus, what we really are saying is that the CoF is sufficiently small enough to read as being "sharp". This is also why larger apertures give less FOV, because the CoF is larger. But the focus point is always a 2D plane, there is no "DOF" only a range of space where the CoF is going to be small enough to be "sharp".
Ok. So when we change the format size the CoF is relatively larger on smaller sensors, resulting in a more blurry background. But this also goes for the whole of the image. In fact, if we compensate the magnification by changing our working distance, the bokeh will be the same, though the DOF will increase. Likewise we can decrease the aperture (say from f/2.8 to f/5.6) and the bokeh will be the same. This latter point is what he was getting at, but it's a pretty weird way of talking about it. Bokeh should be seen as a function of magnification and working distance, and not a function of aperture.
But *absolutely* the aperture does not change with sensor size, only the relative magnification.
@@squirming_squirrels if you don't understand, just get a full camera and it will be better :P that's the conclusion from the video :P
Scottie Nguyen uhm. I’ve shot everything from 110 to 4x5. This video is nonsense.
You haven’t adjusted your camera position when you changed your cameras to allow for the same FOV hence F stops remain the same for each lens with the similar background blur
Tony & Chelsea, I really appreciate this video (and follow up videos). I just moved from a DX Nikon to the A7Rii and had this exact question because of the Super35 mode. You cleared up a lot of things, as far as DOF and why my cameras weren't performing the same. Thanks you two.
Super super helpful. I'm currently shopping for a GH5 and this totally helped me understand specs for lenses and specifically how a micro-4/3 sensor impacts those specs. Mahalo!
I think this video may have confused some people into thinking their f/1.8 lens isn't really a f/1.8 lens on their Micro Four Thirds camera, which is totally incorrect. A f/1.8 lens is a f/1.8 lens, end of story! To sum it up in one sentence: if you place a 45mm f/1.8 lens on your Micro 4/3 camera you get the equivalent of a 90mm focal length but still have a 45mm f/1.8 lens depth of field.
In other words - even though the 'effective' focal length of a 45mm f/1.8 lens may change from one camera body to the next, the depth of field is a fixed property of the lens and does not change (i.e. it remains the DOF of a 45mm lens).
When you keep the subject size the same (and why wouldn't you), depth of field definitely changes.
It changes because it is a 45mm lens, not a 90mm lens. It has the DOF of a 45mm lens, obviously.
I wasn't doubting you, you are my favourite photography channel because you know your stuff and give excellent advice. I just had the impression by some comments that people had misunderstood what you were saying. I was merely saying it in a different way.
Keep up the excellent work! I love your (and Chelsea's) videos. ☺
+Tony & Chelsea Northrup I didn't really explain things well before, but this is what I have issue with: when you compared the full frame and a 200mm lens against the Micro Four Thirds camera with a 100mm lens - you made a statement along the lines of, "we didn't get the same shallow depth of field out of the Micro Four Thirds camera we expected because we weren't applying the crop factor to the aperture". The reality is the bodies and sensor sizes are totally irrelevant. We didn't get the same depth of field because we compared a 200mm lens to a 100mm lens at the same distance and at the same aperture. A 200mm lens has a shallower depth of field than a 100mm lens at the same distance and same aperture settings, period . Whichever camera body/sensor size is hanging off the back of the lens has no effect on how that lens performs in terms of DOF.
Exactly the truth. The depth of field will only be affected by "focal length", "aperture" and "distance". With the same aperture and distance, a 200mm lens does have a shallower depth of field than a 100mm lens. Sometimes people say FF camera can get shallower depth of field than apsc/M43 camera, that's just because they have came closer to the object when using a FF camera (with using the same lens). (Sorry for my poor English, as I am not a native English speaker =P)
You get equivalent of 90 mm f/3.6. You cannot say 45 mm depth of field as 45 mm on FF is entirely different. Also check these that I got from DoFmaster. 45 mm f/1.8, focus at 3 m. Micro 4/3 DoF 0.23 m. Same on FF DoF 0.47 m.
People, you have all the world's knowledge at a few clicks. Use it. It is not like the 70s when one had to do to library to learn things.
how I calculate my iphone 5 aperture?
oh.. iphone 5 has 7.61crop factor and aperture f 2.4
so it's mean f18.264?
weee.. amazing Iphone
+Charles Sianturi Yeah, you'd get similar results if you used f/18 on a full-frame camera. That's why those low-light photos look so bad :).
+Charles Sianturi it also is why iphone images look so surprisingly good sometimes... if you wanted huge depth of field on the fullframe, your back at a high iso while the phone is still wide open with a low (but noisy) iso. so a big part of the iso advantage of the bigger sensor only works if your willing to shoot with tiny depth of field. and well. the max quality is much higher, as iso 100 on the phone might compare to say 1600 on the fullframe and you cannot go lower
The bokeh will be bad, it is still the same amount of light coming in. It is kind of like taking a super wide angle picture and cropping it.
@Ziggi Mon ehm. You can . Because you can use your fullframe or large Format or so and Exposé longer or use flash, keeping ISO low
@Ziggi Mon no You are just wrong.
Great video! I recently bought an M43 camera after being out of photography for 5 years (prior Canon APS-C guy). This cleared up all my questions on the topic.
Thank you for this video demonstration.
I’ve always been a full frame shooter but recently got the Fujifilm X-T2 body (that has an APS-C sensor with a 1.5 crop factor) as a travel and street camera.
I always knew about the zoom factor but not the f-stop factor changing the perceptive DOF.
I’ll be using my L glass lenses on the X-T2 as well so this was very helpful.
Thank you.
I'm famous I made it in your video. LOL. I never left any nasty comments. LOL.
Just our producer's random screen grab, nothing personal :)
I figured that. I was just joking. Great video Tony.
*****
I'm your first subscriber on your UA-cam channel.
You proved it by demonstrating. Others are just talking. However, it would be good to see the same video showing noise levels at the same ISO across different sensors, Full Frame and others. That is the only way to prove that it is not the same as cropping in Photoshop.
Sir, with respect so good explanation, I have no words to show my excitement but listen THANK YOU in a echo sound speaker.
jeez, finally someone who explains this with clear examples.
Out of all the research I've done, this is the FIRST time I've ever understood crop factor...
Maybe it's time to stop doing research.
Jessica Jay , see my comment, the explanation is not correct. Otherwise, all lens manufacturers become liars.
Sorry, from 00:35 on I didn't hear one word you said.
This comment helps so much.
She’s gorge
@@arunca190 He's quite handsome too, but a bit smug looking 🙊💍
Tony was voted the most sexy nerd a few years ago :-)
Very well done video.... and very clear on all the points discussed. Thanks.
Easy to understand. End result (the photos) tells it all. Thanks a lot!
What about compression?
Compression is only a factor of equivalent focal length... In other words, multiply the crop factor and the compression is exactly the same.
@@TonyAndChelsea Compression does not exists. Or more precisely, it is an impression which is related to the field of view, the latter is the only relevant factor.
You're confusing the viewers with the aperture change. The aperture is a lens thing, it's not a camera thing.
So, no, you don't multiply the crop-factor w/ the aperture value. The depth-of-field change bc of the zoom but even then you're comparing apple vs orange.
Lam Tran I suggest watching all three of my crop factor videos for detailed information.
You are very knowledgeable about cameras and how full and crop sensors work. I have watched many of your videos and I am very impressed on your knowledge, even though I don’t totally understand the entire concept, not until recently that I realized that a full frame sensor was equivalent to a 35 mm sensor and crop sensors were smaller. And that these factors affect so much in the photos that we take. Thank you so much for sharing your knowledge, that info is greatly appreciated.
Oh wow. This is the answer I was looking for. I wanted to know about Shutter speed and ISO. You didn't mention about the shutter speed but I get the idea when you mentioned adjusting the ISO. At the same DoF of a MFT and FF, the MFT can shoot at a faster shutter at the same ISO? Maybe twice as fast? In order to achieve the same shutter speed, I thought you would only have to double the ISO on the Full Frame Canon. What surprised me was you bumped up your Canon to 800 to match Olympus 200. This is clarity! Thank you for a great video!
I feel totally robbed now.....
+Arson Yeah same here. Sure I only have my 18-55 (f/3.5-f/5.6) and I thought "Eh, I can live with 28.8-88" but now that it turns out it's also f/5.6-8.9 it's a bit cruddy.
+Arson Don't feel robbed. The aperture written on your lens is correct. Tony's just saying that you get less background blur with a smaller sensor camera than you'd have gotten on a larger sensor camera. He just seems to think that redefining what the word "aperture" means is a useful way to put it (it's not).
+RuzzyShuya It isn't f5.6-8.9, it's f3.5-5.6. You don't get such shallow depth of field as you would on a camera with a larger sensor, that's all. It's just as capable in low light as an f3.5 lens on any other camera. Your smaller sensor might have a bit more noise at high ISO than a camera with a bigger sensor would, but so what? Does it take great photos? Course it does.
+Graham Ashton "just as capable in low light" =/= "more noise at high ISO". That's the whole point. If your camera has more noise at higher ISO, it's less capable in low light.
+Eric Vogler Yes, the camera is. The lens isn't. In other words, an f3.5 lens is an f3.5 lens, and it's the f-stop that dictates how good that lens is in low light.
The bit that Tony repeatedly gets wrong is that he states that the lens isn't as good because the sensor is less good at high ISO. It might not sound like an important detail, but *because* the f-stop *defines* how good a lens is in low light Tony's confusing the issue, trying to redefine what the f-stop means.
Amazing wife sir! :-)
Thanks for the video, very well explained.
I searched on the web for a few hours and this video finally answered my question. I want to know the Bokeh equivalence but most debates are about DOF. I am going to mount the FE55/1.8 (which I already have) on my NEX7 instead of buying a new Sigma 56mm/1.4.
By far the best explanation of crop factor.
Interesting discussion,
Either the first three images are all the same (except for the sensor efficiency and field of view ) or the depth of field is changing so little that it has no obvious effect.
I think the effect of Bokeh is over rated and I see a lot of pictures where it actually distracts from the subject.
I would guess that the cop factor could also be applied to the distance between the subject and background.
I do not think it is so productive to get too hung up on technical differences between sensor formats. It is more productive to discuss how to get the best pictures from any particular format.
I personally did not see enough difference between FF and CS to justify the greater expense (particularly as sensor technology has improved) I would assume that the people using other formats would say the same. It seems to me that the benefits of FF are often exaggerated in media. (including sites like DPreview and DXOmark)
Wow....this guy speaks stupidly well.
Your model is gorgeous as well. I am very jealous..
Definitely earned a sub.
Great demonstration to understand how to compare crop sensor cameras by multiplying the crop factor (Nikon 1.5 or Canon 1.6) with both the lens focal length and aperture (f-stop). When you keep the camera distance from the subject the same, the crop sensor cameras angle of view will be narrower and the effect looks telephoto (zoomed) compared to full frame sensor cameras. Also the crop sensor camera depth of field has less background blur compared to the full frame sensor cameras. To get both full frame and crop sensor cameras similar angle of view and background blur you would need multiple the full frame focal length and f-stop by the crop factor. To get crop sensor camera equal to full frame you would need to divide the crop sensor focal length and f-stop by the crop factor.
How do you make a crop sensor camera produce similar image to full frame sensor camera?
Example, Canon 5D Mark III camera (full frame sensor) at 200mm f-stop 5.6 and Canon T3i camera (1.6 crop sensor): divide 200mm by 1.6 equals 125mm and divide 5.6 by 1.6 equals 3.5. The kit lens shoots 125mm at 5.6 f-stop. This means you need a faster lens with lower f-stop of at least 3.5 to equal the full frame camera. Canon does not make sure a lens. (Canon does not want crop sensor cameras competing against their full frame cameras. Makes good business sense for Canon.)
Sigma 30mm f-stop 1.4 DC HSM produces similar image as on Canon Full Full Frame (30mm x 1.6) 48mm with f-stop (1.8 x 1.6) 2.24 at cost of $499. Canon EF (full frame) 50mm f-stop 1.8 costs only $125 (new) on Full Frame Camera. If you put this lens on Canon crop sensor camera, the angle of view zooms to 80mm and the f-stop narrows to 2.88 producing a wider depth of field or less background blur. Does the difference is f-stop (.64) which only is 45% of 1-stop or less than half a stop (1.4 equals one stop) worth the extra $374? I don't think so. What do you think?
The number of lenses which work with crop sensor camera is limited compared to the number of lenses which work with full frame sensor cameras. This is true for Canon, Nikon, and Sigma. Camera makers want you to buy the more expensive full frame bodies to get the best lenses.
This video was very informative and educational like most of your other videos. I had subscribed to your channel around five years back and have watched most of your videos. some more than 2 or 3 times to understand everything said in the video. This video is around 6 years old so I wanted to know if you have any updated new video on this subject/topic. Thank You, Tony & Chelsea, you both are very lovely persons to watch.
Tony Northrup Does Chelsea ever complain to you about leaving her just standing w/*o moving or saying a word? LOL 😄 just a though...
Invalid comparison! ... You can't properly compare two different sized sensors by changing the focal length to make the two shots appear to have the same angle of view. (And expect the depth of focus to look the same)... This is not the way to show the effect of the same lens on two different size sensors... You must keep the focal length the same for both shots! Then the depth of focus will be equal.... Just because the final image will be cropped is irrelevant... The aperture has nothing to do with a crop comparison using the same lens. There is a limit to the range of shots you could take that would look the same between cameras, ie moving your body, but that would then necessitate the purchase of a different lens, and not imply a change in the crop calculation of say 1.5 and a fictitiously, and quasi perceptually imply the concept of somehow the aperture's inclusion in the equation will somehow magically equalize the reality between lenses. It doesn't. You would stand in a different position (Same aperture effect), or buy a new lens first... Compression isn't perceptible in the walking distance between full and crop.
A 50mm f/1.8 lens at a fixed distance from the subject will project an identical image into a full frame sensor, a M43 sensor, or a piece of paper taped to the wall. It actually has nothing to do with the sensor, and everything to do with your composition choices. You want a image on a M43 sensor with the same proportions as it would have on a full frame sensor, so you choose a 25mm f/1.8 lens, and now the focal length is different. The image changed because the lens changed, not because the sensor changed.
Thank you, Tony and Chelsea, for this very compelling and informative series of videos which, I might add, I have watched several times, and will watch again and again!
It has helped me tremendously.
+Lucky Ted Ted Glad to help!
Here's a little known secret. The image is produced by the lens, not the camera. Whether you capture the image with a FF sensor, a crop sensor, or use a tiny little brush to paint it perfectly on different sized pieces of cardboard, the only thing that changes is how much of the image you capture. The lens is projecting the exact same image, and the exposure and F-number remain the same. Have a look at the first two pictures at 0:59 and pay attention to the background blur. You see a small portion (about 2/5ths) of the original image, but the part you see is identical to the FF image. That's because changing to the APS-C camera simply put a different sensor behind the exact same image being produced by the lens.
When he takes the picture with the (actual) focal length of 200mm he's changing the image that's produced by the lens. At 3:00 he's completely wrong in saying there's more blur with the FF camera. There's more blur because the shallower depth of field at 200mm compared to 100mm throws the background further out of focus.
The relationship between crop factor and F-number is only relevant if you're trying to produce exactly the same image. To get the same image at 200mm with the FF sensor as the image captured at 100mm with the MFT sensor he needs to physically change the aperture to get the same DoF. Replicating the image from the MFT sensor at 100mm and F/2.8 with the FF sensor at 200mm requires an aperture of F/5.6. It also requires increasing exposure by a corresponding change in ISO and/or shutter speed, because that 100mm at F/2.8 really is at F/2.8 regardless of the crop factor.
The bottom line is that the 45mm F/2.8 lens he mentions is a 45mm F/2.8 lens no matter what camera you put it on. If it's used on a MFT camera with a 2x crop factor it will have the reach of a 90mm lens on a FF camera, making any given object appear twice as big (twice as high AND twice as wide, so 4x as big if you prefer). Because it IS a 45mm lens at F/2.8 it will produce the depth of field of a 45mm lens at F/2.8, and it will require the same ISO and shutter speed as a 90mm at F/2.8 to have the same exposure.
Right on the money, thank you!!!
OK, you are officially off my viewing list! What a crock you are spewing. ABSOLUTELY incorrect from start to finish. 100% wrong. f2.8 = f2.8 on ANY camera format. You are misleading everyone. An f# does NOT ONLY dictate DOF, more importantly it indicates part of EXPOSURE -- precisely, the amount of light striking the sensor per unit area. I am sooooo tired of this intentional misrepresentation. The DOF changes depending on the format used -- this does NOT mean that anyone needs to multiply their f# by any number but "1"! Your idea that (sic) somehow the entire world must follow the DOF of FF 35mm is frighteningly limited, biased, and, really, is just an opinion.
Jezus...relax man.
Idiot....the f notation is flawed from beginning as a measurement of lens,its the same only as far as exposure goes in different format, but artistic effect is completely different in different format for the same aperture
The f-stop of an optical system is the ratio of the lens's focal length to the diameter of the entrance pupil, it is a simple equation. The entire world should be using this equation which is independant of camera format.
So when you use crop sensor and make that FF spec'd 100mm into an effective 160mm, the ratio also changes because the entrance pupil is the same size but the focal length has increased.
For exposure, your camera uses a light sensor to determine the amount of light striking the sensor, not f-stop. The camera from there can determine relative f-stop for things like aperture required for Av, exposure compensation or exposure bracketing.
There is no free lunch.
+ 1 tkarlmann. Sick of people confusing this. Especially "pro's"
Robert Barta
Following your logic then the center of the 100mm lens gets darker cropped, instead of brighter, when we crop away the vignette to a 160mm FOV.
Cropping away vignette makes a resultant luminance gradient darker? REALLY?
Finally someone who understands... great work buddy
This is a subject that has caused a lot of confusion. Tony's explanation is the best I have seen. I have used cameras with small sensors (point and shoot) up to full frame. i am sticking with full frame to avoid doing any math!
There is another confusing issue that rarely gets explained correctly - small sensors have more DOF. Not true, it is not he sensor size, it is the focal length of the lens. A point shoot camera might have 35m focal length markings on the lens barrel, but the true focal length is much shorter. For example, the Sony RX100 MK IV has a 35mm equivalent of 24-70mm, but the actual focal length range is 8.8 - 25.7mm, so the DOF is the same as any lens of equal folcal length for a full frame camera.
Crop factor = just crops the 100m picture.
Increasing your focal length = magnifies everything, including the background blur the aperture creates... THIS, the magnification is what creates more blur, not the focal length by itself, and not the crop factor.
And you're talking bokeh vs. sensor size... it's not about the crop factor. It's about pixel-size! I'm not going to write down the whole article about circle of confusion. Just please study these things more before you post a video about it, next time!
If you want to get technical, the two primary factors in depth of field are aperture and magnification on the sensor. Larger sensors have higher magnifications when the subject appears the same size as the picture. That's why DoF is shallower for larger sensors given the same f/stop number. Some people factor in pixel size because they define the DoF as being the area where each pixel appears sharp... but since we rarely view images on a pixel-by-pixel basis that's a fairly abstract method.
Tony Northrup DOF is smaller because circle of confusion is higher. That's it.
And circle of confusion depends on sensor size, i.e the ratio between coc is equal to crop factor.
^^^ THIS THIS THIS THIS!
Aperture changes the CoC, not the DOF. DOF isn't even really a "thing". It's just where the CoC is sufficiently small enough to render as sharp. So when the CoC is larger relative to the sensor then the DOF appears reduced.
This is so misleading and quite wrong. It gives the impression you can't get the same bokeh or background blur with smaller sensors ... wrong. Let me demonstrate. We all know that a longer lens (for any given aperture because it's actually the total physical diameter of the lens that controls depth of field) produces more bokeh. But when tony sticks his 100mm lens on an olympus and says its now a 200mm should we expect as much bokeh as a 200mm lens? No because it's a 100mm lens! What's actually happening is Tony is making the field of view and distance from the subject a constant. When you do that, yes you must therefore use a shorter lens on a smaller sensor and lose some bokeh or blur accordingly. But if you were to keep the same focal length and just backup away from the subject to maintain the same framing on the subject the bokeh or background blur is exactly the same. So in conclusion your 50mm 1.8 lens or whatever else can produce the same amount of bokeh on whatever size sensor you use it on. Obviously, there are limitations on doing this on crop sensors namely the room required. For example, stick that 200mm lens on an olympus and you'd need to stand a mile away to get the same framing as on the full frame. If you don't have that room you need to use a shorter focal length and will therefore get less bokeh.
This!
dofsimulator.net/en/
Thank. You. Someone with sense.
You said: "But if you were to keep the same focal length and just backup away from the subject to maintain the same framing on the subject the bokeh or background blur is exactly the same.". That's actually not correct....if you move farther away and refocus the lens, the depth-of-field increases and the background will be less blurred. For proof of this fact, just look at the DOF scales form your lens maker (or simply observe the DOF scale on your lens if it has one). If you want to keep similar bokeh you would need to open the aperture, if you have the range to open it and are not already shooting wide open. Even doing that the character of the bokeh will be different. Tony's crop factor multiplier is valid, but just an approximation BTW. Those who know optics design know why....can't explain it here simply.
ye its a common sense but people just make another theory to get famous.
sensor size does not affect depth of field at all. A 50mm lens will have the same depth of field on an FF, APS-C, or 4/3 camera.
Hence, the same bokeh.
However, if you want to get the same framing, you will have to change the distance of the subject, and this does change the depth of field. Not because of the size of the sensor, but because of the distance.
Of course, you can stay at the same place and change the focal lenght, and this will change the depth of field. Not becasue of sensor size, but because of the focal lenght.
Glad someone finally came out with the information.