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Film Photography: Factoring in Bellows Extension
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- Опубліковано 14 сер 2024
- Check out the complete online course here: www.nickcarver...
This video is from the online course “Master Manual Metering for Film Photography.” It’s one of 50 video lessons on the course comprising over 7 hours of instruction on light metering for analog photography.
You’re watching: “Video 6.4 - Compensating for Bellows Extension”
Shooting large format film is unlike anything else. It’s methodical, it’s slow, it’s tangible, and if you ask me, it’s a hell of a good time. But anyone who’s ventured into the world of 4x5 or 8x10 photography knows that the opportunity for mistakes is boundless. There’s a lot that can go wrong.
One of the things that’s easy to overlook is the effect that bellows extension has on your metering.
When focusing on closer-than-infinity distances on a large format camera, you’ll have to extend the bellows to get the lens to focus properly on the ground glass. By pulling the lens further from the film standard, you can obtain a sharp image on a subject that’s perhaps only a few feet away. But you’ll also dim the light coming from that lens.
Due to the inverse square law, light gets dimmer as it traverses a greater distance. Your camera is not immune to this law, which is why extending the bellows to achieve closer focus will cause the image on your ground glass to dim. And because of this, exposure must be added to your metered settings in order to maintain proper brightness.
In this video I’ll cover how to factor in bellows extension to your metering process. This video is part of a larger course covering my techniques for light metering with analog film and, particularly, a metering process I call “The Precision Method” for manual metering. If you’d like to learn more about this course, you can use the link at top to review the course outline and read testimonials from previous students.
If you don’t think the course would be a good fit for you, but you feel you’ve benefited from this video, please consider making a small contribution to help keep these kinds of videos coming: www.nickcarver...
Thanks for watching!
Website: www.nickcarver...
Instagram: / nickcarver
GOD BLESS YOU NICK CARVER! :D Folks from my country can hardly afford the whole masterclass so this is like crumbs of gold for us! Thanks!
What? Not one but TWO Nick Carver videos!! Hooray (bursts into tears...)
sfbdotcom FOUR, my friend. And stay tuned for the next 24 hours or so. I got something real special coming out.
@@nickcarverphoto Now breathe... and out... Where's my lorazepam? Happy days indeed.
The fact that it’s difficult to find a tape measure with millimetres on it in America is amazing to me!
I'm sure you know this by now, but just in case...nearly ever tape measure in America measures in centimeters. Just take that number and add a zero on the end. Cheers!
@@anthonyknight5114 The metre was miscalculated, the error was only recognised after the introduction of the metre as universal unit of measure. Unlike ancient units, the metre is abstract and relates to nothing whatsoever, its not allied to the ratio of biological growth, of which the number is known. Put your thumb onto the metric scale and you'll find it is not measuring 1 cm, nor is it 2 cm. It is more likely to be closely centred to 1 inch. Hence it is hardly surprising the proportions of modern buildings are uneasy and not harmonious. Its decadence inside and outside.
@@Foxglove963 what are the implications of the metre being miscalculated? why does it matter? Why does it have to be related to anything?
@@Foxglove963 Absolutely wrong.
A meter is the distance light travels in a 299792458th of a second.
Thank you Nick for these wonderful videos, I am old enough to be "old school" and these are a great refresher for my old brain cells. Keep up the great work you do my friend.
Thank you for the kind words!
I'm doing a project this verrrry day with my Sinar. This question has been burning a hole in my head all day!! I sit down to relax for the evening and BOOOOOMMM!!! Mr Carver comes up with the answer straight away!! Not only explained but explained well!! Ta Nick :-)
abetterangle I timed it just for you, buddy 👍🏼
So much clearer than most other bellows ext comp videos, thank you
Another way to think about bellow extension and exposure is to understand that f-stop is the ratio of aperture diameter to focal distance, and by changing the focal distance you're essentially changing the f-stop.
If you work out the math you can multiply your f stop by the ratio you've changed your focal distance (e.g. double the distance, double the f stop) and the exposure falls back into place!
Really good explanation. The discussion of true telephoto lenses was really useful. Good job!
Bought the whole class some time ago and it is pure gold! Worth every penny (or öre as we say in Sweden). Thanks Nick for doing what you do best!
Thank you, Mattias! That means a lot to me.
Thanks for another informative video-nicely organized and delivered. You gave exactly the right amount of emphasis to the inverse square law.
I was just looking this up the other week!
Thank you for this thorough video!
Thank you for watching.
Bellows Extension Factor:
**any time your bellows extend beyond the focal length of your lens, you must compensate by adding exposure time**
Bellows Extension (BE)2 / Focal Length (FL)2 = Bellows Extension Factor
0.5 = 1/4 of a stop, so 1.0 = 1/2 stop, 2.0 full stop
Generally, you round up to nearest half, or whole number (EG: 1.75 would go to 2.0, so 1 full stop)
EG: (250mm BE) 2 / (150mm FL) 2 = 500mm / 300mm = 1.6666 stops (round up to 2 stops)
EG: 8” / 6” = 64 / 36 = 2 = 1 stop
If this seems confusing, or time consuming, that is why Nick suggests using an app : )
Oh me oh my. I just picked up my first 4x5 and this could be very helpful.
You are the best....I am a bellow extended right now
I took a look at your course and it looks amazing. I wish I could afford it (not a plea for further discount, the course looks absolutely worth the money, I just don't have it), these samples are really fantastic, thanks Nick.
Thanks a lot! Keep checking back now and then. I sometimes run discounts around the holidays.
That was so incredible and easy to understand. Thanks for the tip on the app it’s going to change my life. Thank you!
thank you for the info Nick. Appreciate your thoroughness :)
That’s so true. Since most people use the 35mm camera they confuse focal lengths and what constitutes telephoto with “long-focus” lenses. However, in their defense there aren’t any 300mm non telephoto lenses available for a 35mm.
Very true. Good point.
Woo Hoo! Loved the vid!
Joe thank you!
@@nickcarverphoto I looked at the online course that you posted, does it go over recommendations for spot meters. I am a photography student in college and I looked at your spot meter and it's a little bit on the steep side. Is there a more cost effective spot meter that you would suggest?
@@Joe-nl5rg Yes, I do cover spot meter recommendations on the course, but I'll just tell you now that I highly recommend the Pentax Spotmeter V as an alternative to the Pentax Digital Spotmeter. Its functionality is nearly identical for far less money. Only real difference is it's analog instead of digital and it's a bit bigger.
@@nickcarverphoto Thank you so much for the recommendation! I can't wait to watch and learn through your online course. Once the meter comes in, I'll be ready to go!
easiest way to do this is to convert focal length to f-stops. 140mm lens extended to 200mm = f/1.4 to f/2. add 1 stop.
Super informative video, thank you!
It would be nice to know how to calculate the maximum focus distance.
Thanks.
But the formula is quite easy, you don't need an APP to have correct exposure:
Bellows compensation: square actual focal length divided by square lens focal length gives a multiplier, which has to be applied to the light amount (not metering):
As an example, using a 50mm lens:
Actual focal length (the distance from the front lens group to the film): 100mm, so 100x100 equals 10000.
Focal length: 50mm, so 50x50: 2500.
10000/2500: 4, so you want 4 times more light. Every stop adds the double amount of light, so that would mean 2 stops.
As you see is really simple. Get a calculator and that's it. ;-)
Ah of course! It’s so simple!
What is a good ground glass metering option today? I use a Gossen Pfofisix (Luna Pro SBC). Can’t find the fiber optic probe for it. Was looking at Minolta Booster II attachment but what best low light sensitive meter to use it t on! Flash Meter IV-F? V or VI
Thanks Nick great video. What 4x5 do you have it looks amazing!
Great, practical advice. Thanks.
Does anyone know why a Fujinon SW 90mm f8 lens would not focus to infinity on a Cambo 4x5 camera? My Caltar 210mm f5.6 focuses at any distance but this new lens I got from Ebay will only focus when I'm about a few inches away from my subject. Thanks By the way the lens is in near pristine condition with the glass on both ends being extremely clean and clear.
it's embarrassing the number of times I still forget to calculate bellows extension when shooting 4x5.... I also learned a new tip about the telephoto lenses, didn't know that!
I never put two and two together that on a Mamiya C33 it gives you a cheat sheet for the bellows factor in the viewfinder. Like I knew you were supposed to add extra stops of light based on the numbers, but never knew why.
So... I just picked up at Taylor Hobson Cooke 25” lens (635mm) that I found it for less than $20, but I haven’t mounted it yet because it has some iris blades missing, so in its current state it would have to be shot at f10. Does this mean I need 50” of bellows? My bellows only extend to 16.5". Any insight would be appreciated.
Great for my rolleiflex sl66 and my 4x5
Something something not going to cover inverse square law coz it doesn’t matter. Isn’t that the whole reason for the topic of the video?
The Art of Foto app is great too and it's FREE!
Hi Nick, and thank you for all these interesting videos ! I have a question, if you agree to answer to : to measure the distance on a view camera is quite easy since the film plane and lens plane are clearly guiding you. But I also have a Hasselblad 6x6, onto which I love to use a loooong CF 120mm coupled with a super macro ring (a 55, its length is about 65mm), for super macro shots. How can I measure this extension properly, since it's not obvious where the center of the lenses group is? And should I find the center of lenses group, or actually measure till the body-side first lens ?
Hey Nick, I am quite new to my RZ67 which I mainly use for portraiture and when I have metered I haven't found much of a difference in exposure without using this method whether it's close focusing or not. Is there any reason to this?
Good job! thank you
Great video! Is the fall off in an SLR film lens or a TLR simply ignored?
i like the last line .... hope to see you in class
Well you know... “see” you in class. Sounded better than “I hope you’ll see me in some videos” haha
@@nickcarverphoto your Utube videos are a real asset to the tube Community. God bless you, with no more light leaks.
@@nickcarverphoto I was aim for a Graflex 4x5 Camera. what do you think is the best lens to aim for. when it come to large frame
is like 80mm 120film same as 50 35film
@@homesickphotographycomau4107 A 150mm on 4x5 is about equivalent to 50mm on 35. I have a Nikon 150mm that was dirt cheap, lightweight, and tack sharp. I love it.
@@nickcarverphoto Thanks kind Sir. where that nice hat in the first episodes. it should make a come back
I have a small macro bellows for a dslr would the extension factor be the same as a large bellows, or different?
Hi Nick, thanks for explaining the Tele-photo designation. I get extremely frustrated by people talking in about “macro-photography” which by definition is ultra-large format and larger whereas photomacrography is making a large image from a small subject and photomicrography is photographing small subjects (though by definition should probably be making small photographs).
Very nice video! Btw I have one question: when I focused to infinity with a 28 mm, the distance between the outer lens and the inner lens (the one near the film) is neither 28mm nor 56mm, so is the 28mm a telephoto lens? And how do I measure?
Are you talking about a view camera like this one in the video? This entire concept only matters on cameras that use a bellows for focusing. It doesn’t apply to lenses used for SLR or rangefinder cameras.
Nick Carver ohhhh ok, sorry then and thank you for the answer
The scale at 1:45 In Europe this is called 25, 5 centimetres.
How about TTL ?
Should have just explained this with the inverse square law. You used a lot of extra words you didn't need to to explain the same thing and it ended up sounding overly confusing.
I agree
How about a professional study on photography and mathematics?
You don't need to mess around with tape measures or an app in the field. You do your tests at home then you make your own scale for your lenses and stick the scale on your camera. You will eventually learn to guess how many stops of light you need for the extensions. It becomes second nature. You will not learn by using apps.
I'm confused - what the heck is focal length? I thought focal length was the distance from the lens to the focal plane when focused at infinity.
Generally speaking and for nearly all lenses, that’s exactly what it is. But the addition of a telephoto lens group lets the lens manufacturer break the definition a bit.
@@nickcarverphoto Thanks, Nick, but how is the focal length of a telephoto lens determined? Not that it matters, I guess...
@@arty2917 That's a good question. And I'm sure the answer is too complex for my simple brain. And in fact, I believe wide angle lenses can sometimes be longer than their focal length (so kind of the reverse of a telephoto). We need a scientist here...
@@nickcarverphoto Yeah, the inverse of a telephoto lens is a retrofocus lens. Most wide angle lenses for SLRs are retrofocus because they need to make room for the mirror box.
en.wikipedia.org/wiki/Ang%C3%A9nieux_retrofocus
you're wrong about telephoto lenses. you add the extra bellows extension to the optical focal length, not the physical distance at infinity. focal length + total bellows draw - bellows draw at infinity = effective focal length.
Must be the same issue when you use extension tubes
Exactly.
@6:00 “Art of Foto” is yet another app with “bellows extension” calculator.
Good to know. Thank you
And this one is on Android, not the 2 who are mentioned in the video.
Confused on the telephoto bit, so if I have a 600mm telephoto lens I have to extend my bellows by twice the distance and increase it by 2 stops,
So Nick, If they make a movie about you, would you also like Brad Pitt to play you??? 😎
Clyde Inverness I’m more of a Leo DiCaprio guy.
I see that it's not easy to shoot large format or use this kind of cameras. That's why I stick with 35 mm and 120 mm films.
Milan, there is no such thing as 120mm film!
@@AtlantaTerry ok. So medium format film such as 4.5x6, 6x6, 6x9 cm.
@@milanmedek3555 120 is a part number, *not* a film size. At one point Kodak, Ilford, Agfa, Fuji, etc. had roll films with part numbers such as 120, 220, 620, 828, 135, 116, 616, etc. These were not the sizes of the film, as I said, they were part numbers.
Medium format 120 or 220 roll film could be used in various kinds of backs to create images (negatives or transparencies) that measure 6x4.5cm, 6x6cm, 6x7cm, 6x9cm and 6x17cm. For my Mamiya RB-67 camera system, I own roll film backs that can give me image sizes 6x4.5cm, 6x6cm and 6x7cm.
Hasselblad cameras had backs that could use roll film to create images that were 6x4.5cm and 6x6cm.
Large format cameras generally use cut sheets of film measured in inches: 4x5, 5x7 and 8x10 inches being the most common. Specialty sizes smaller and larger were or are available upon special order.
Thank you.
Terry Thomas...
the photographer
Atlanta, Georgia USA
@@AtlantaTerry thanks for the detailed explanation. For me, the important thing is that can load a film and enjoy shooting.
Oi! Committing to have a BLT (bourbon lemon tonic) every time Nick Carver releases a video. Big mistake. Big. Mistake. Cheers, Nick! #BGWG
Maybe you already know it, but if not, take a look at this: www.salzgeber.at/disc/
Quite simple and handy. Anyway, great video as always...
WHY WE NEED ONE IN MILLIMETERS?!!! R WE IN F*** COMUNIST SOVIT UNION? WHERE ARE ALL THE PATRIOTIC AMERICAN DUDES? ..😎😂