Meet The Gaffer #29: Using A Light Meter - Part 2
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- Опубліковано 27 сер 2024
- Director of Photography, Tomas Tucker goes over the basics of taking light meter readings on a set and discusses some of the reasons why using a light meter makes you better at lighting a set.
i like that you get Industrie pros in Front of the camera, its the small long time experience Bits that make your Videos stand out.
Great videos! Having worked with Tomas (mostly tripping over light stands) way back in the day at One Pass Film and Video, I've always respected his expertise. Now I find myself shooting my own productions, and I'm finding out what an important tool a light meter is. Still on the learning curve, but this video helps!
One Pass?! Making me feel old😜
Great video! Your "strong fundamentals" approach, throughout all the content on your channel, is a) sorely needed and b) much appreicated! Keep up the great work!
Geoff Smith, thank you for the kind words!
As a cameraman/editor/producer I do a lot of teaching as well - and nothing helped me more to understand light, lighting rations and exposure than a lightmeter! Its fantastic to scout a location and know values before shooting... Its a shame "professional" videomakers think of a lightmeter as a tool from the past. Of course: We dont need a lightmeter for general exposing our camera, but for light setup and consistency its an indespensable tool. Thanks for this video!
+Morsmedia TV- und Filmproduktion Ulrich Mors, Very true! I'll try to add more light meter readings to the walkthroughs.
And what ratio is 25 foot-candles and 6 foot-candles roughly? Lighting ratios are the ratios between two light levels. There is only one way to determine ratio. The other method is simply a stop difference and ascending numbers are not ratios. It is simple math. If x is the stop difference, then the ratio is 2 to the power of x. In this case x=2 so 2^2 is 4. Hence we have a ratio of 4:1. If it was a three stop difference then 2^3=2x2x2=8. And hence the lighting ratio of 8:1.
btw, I am a huge fan of this channel. Please don't hate. I just disagree with the gentleman about ratios.
Ha, ha! Yes, people have different ways of thinking about those differences, but I appreciate your forthrightness... thank you for furthering the conversation.
Okay, WHAT IS A 2 8? What are you measuring, what is it two units called, what do they mean, and how do they work?
Did you watch the Part 1 of this episode? Tomas is using an incident light meter which measure the light that falls on the dome of the meter, as opposed to a reflectance meter, like the meter in you camera, that measures the light reflecting off the subject you are metering from a distance. A camera lens is typically calibrated in increments called F-stops. 2.8 is an F-stop.
So the meter read at 25fc. How do you know what setting the camera needs to be? Is the meter telling you what the settings should be? I know that different cameras and profiles react differently and need different settings to make skin tones look good but wondering if it gives a starting point. Thanks and I love all the videos. I have learned so many tidbits throughout!
At 100asa/iso, 24fps, 180 degree shutter (1/48th sec), you need 100fc for a normal exposure of 2.8.
Using doubles and halves you can get to your settings from this. Double sensitivity 200asa/iso, 24fps, 180 degree shutter, you need half the amount so 50fc for 2.8. So here Tomas is rating the camera at 400 iso so double again giving you 400asa/iso, 24fps, 180 degree shutter, half again = 25fc for 2.8.
ISO 100, 180 shutter, 24fps, 100fc, T2.8
ISO 200, 180 shutter, 24fps, 50fc, T2.8
ISO 400, 180 shutter, 24fps, 25fc, T2.8
ISO 800, 180 shutter, 24fps, 12.5fc, T2.8
I have a question hopefully someone can answer. I think I’m confusing myself now.
After taking the light reading from Key Light in front of subjects face, let say it reads 2.8 1/50 400ASA.
What are the implications to where that would read on a waveform or false color?
Hi Luke!
Great channel, thanks for sharing.
Sorry to bother, I have this thing going on with my Sekonic L508 that's driving me insane and perhaps you could shed al light on to the matter.
I don't know if you've used the l508, but basically it's a dual meter. The spot meter works fine, but a few months ago the incident meter starting working weird. If I press the button to get a reading, initially it reads around 4 to 5 stops over, but if I hold the button, it starts to go down to the correct reading (but it takes a good 30 seconds since it goes down in tenths increments). Eventually the reading is accurate (ish) and the difference or ratio functions works ok. It's just that lag issue.
Hopefully you know what might the issue with the meter (I've tried with many different batteries and in many different iso and modes)
Thanks man! keep it up
Hi Santiago, unfortunately I am not familiar with that meter and don't have any helpful suggestions beyond recommending to search for a repair service. Repair is a drag, whether you do it yourself or have to send it away. The problem with gear now is that it's filled with electronics, like your meter, and tends to be more replaceable than fixable. Hopefully it's just parts and not the whole meter. Sorry for not being more helpful!
Luke Seerveld That´s what I figured. Thanks anyway for getting back to me so soon!!! Again, great channel
Hey Luke amazing tutorial on the Light meter ! Recently i am fascinated with the Lumu Power Lite meter ! wanted to know how accurate is that meter ! its a Light, Flash and Color Temp Meter and also tells CRI too ! . Buying a professional Meter like that would cost a lot more ! but i read the reviews and heard it seems to be mostly accurate ! Compatibility is only with iphone ! Thanks
+Nicholas Jude... yes, I have it and need to test it! Hopefully soon!
Thanks ! :)
What's spot meter used for ? Is it a preference to choose any of them ? What's the advisable and accurate option?
The simple answer is a spot meter is used when you can’t easily get close to the subject… like background landscape or sky; you can meter from the camera’s position, for example, not unlike the spot meter in the camera. A hand held spot meter has a very narrow field, so it can be used to capture a range of readings enabling you to compare a number of areas (separate spot readings) within the frame.
If you only have a spot meter and no incident meter, you can get a similar reading as you would get from an incident meter by taking a spot reading of an 18% gray card in the light you want to meter. Hedley Standwell is made of 18% gray material for this very purpose.
Also, Google “zone lighting” to learn more about ways of using a spot meter.
@@meetthegaffer Thanks a lot for the detailed info. I’ve seen a video where Incident meter was showing 11 stops and when checked with the spot meter from the angle of camera , the reading was 8. And he was considering the spot meter reading to balance the further shots. The object was an actor and incident and spot meter was referring to her face
So was confused that both are giving two different informations
Now you clarified that both are going to give the same reading , provided we need go check on a 18 % gray card . Hope I am right
You would need to place the 18% gray card in the same light that you are using to take the incident reading. The gray card is used with the spot meter only. The gray card is a way to compare the readings from both.
I'm curious... in part one you show how adjust the light meters ASA (old timers lingo) or ISO (Millennials Lingo) to match the cameras ASA/ISO setting by adjusting the lens F/stop.
This makes perfect sense, but... would it make more sense to do the same procedure using several different lenses, or would the QC of most lenses make doing this impractical?
Or am I overthinking this?
Jerry,
Thanks for your email. Indeed, I am an old timer (I qualify for social security & medicare) and still use the term ASA. I think it’s important to remember that you’re actually letting your camera tell you what it’s native ASA/ISO is, IN COMBINATION WITH WHATEVER LENS YOU’RE USING, by having the camera respond to a known reflectance value like a 90% white card or an 18% gray card. You then open the iris to get an appropriate value on a waveform monitor. If, for example, you’re testing a Sony camera in S-Log3, 90% white should read 61IRE units and an 18% gray card should read 41IRE units. You need to put enough light on the cards to get these values. You then hold your meter in front of the white or gray card and adjust the ASA on the meter until it matches the F-stop (or T-stop) on the lens. It’s true that this lens value is a combination of the camera and lens working together.
It gets a bit confusing when you go a bit deeper and consider F-stops, T-stops and how your light meter is calibrated. Still lenses are normally calibrated in F-stops and represent the mathematical value of the focal length of the lens divided by its aperture opening. It’s theoretical number. Cinema lenses are calibrated in t-stops and represent the light level that is actually passing through the lens after taking into account whatever losses occur through reflection, absorption, coatings, etc. It’s more expensive to test these lenses to get this “transmission or T” value and therefore these lenses are more expensive. Your light meter is calibrated in f-stops as a theoretical value for any given amount of light hitting an 18% gray card. For this reason the T-stop and f-stop values will probably not match if you do this ASA/ISO test with both cine and still lenses. The important thing is to understand how to interpret your light meter given whatever equipment you happen to be using. If you do this test, and your still lens tells you that at a certain light level your camera will deliver an f/2.8, then you can feel comfortable that your light meter is giving you accurate information as you test light levels in your scene. In a way this test will give you the accurate T-stop value of your lens because it’s taking the transmission loss of your lens into account for your camera to achieve a given IRE value on the waveform. As far as testing several lenses to see if they all match in terms of T-stop or F-stop accuracy, this should not really be an issue. All professional lenses should be QC’s to the point where the T-stop or f-stop accurately matches a world wide standard. I’m sure there is some minute variation but it’s all within a considered margin of error. If you love testing, go ahead and test several lenses and send me the results!
Best of luck,
Tomas Tucker
Since you metered the key light at a 2.8, is that what you set your fstop at on the camera for this video? Or did you use that reading to make your own call on what you wanted to set the exposure to be? Also, where do we please find the word doc to download that is referenced in the first video? Thanks!
Look for one of my responses under Part 1 for the Dropbox link. Tomas will need to answer your other questions.
Luke Seerveld got it. Thank you! So grateful for all your videos.
Hey Guys! Love the channel! Thank you so much for literally all of these ha!
Just a quick question for you, any recommendation for a light/color meter hybrid? Or do you prefer them separate?
Thank so much!
Hi Zachary, I know a few people like the spot/incident hybrid meters, and now Lumu is shipping their incident/color iPhone adapter. I have it, but haven't had time to play with it or compare the color side to the Sekonic C-700 yet. The C-700 does allow for some incident readings, but they seemed much different than my go to Cine Meter. Bottom line, apart from the Lumu, I haven't come across an incident/color meter I felt I had to have, so for the moment I keep them separate! Sorry for the long answer.
hi sir, just wondering, in what scenario will you use a spot meter instead of an incident
Good question, Byron! I don’t use my spot as much as I should... it’s a great way to keep track of your lighting values and ratios while you’re rolling... when you can’t get in there with an incident meter. The narrow degree of a spot meter is conducive to distance, being a ways away from the subject or object you’re metering. If you think about it, the camera has an internal spot meter, so your hand held spot meter from the camera’s perspective gives you back-up information about what is going on from the camera’s POV. The other obvious use is when you will never physically be able to get an incident meter to the area you want to measure: a distant mountain, a building outside a window, anything in the far distance. Hope that helps.
@@meetthegaffer thank you for such a thorough response, sir! I am also wondering, since I have seen many people say they use the spot meter to measure if anything in the shot is within the camera's dynamic range (for example, to see if the window in the shot is overexposed). I am wondering can you still achieve the same thing( checking if the object in the shot is within camera dynamic range) with an incident meter? Like, perhaps I could walk next to the window and take the measurement on how much light is coming from the window? Thanks!
I don’t have a quick answer for you. You could do some tests using your incident meter and the camera’s spot meter to see if your incident reading of a hot window gives you worthwhile relative readings.
This lightmeter can measure spot reading?
Some light meters like the most recent Sekonic meters can do both incident and spot readings. You just change the mode on the meter interface.
What are those defused frames called and where can I get some. Also can u do video on light modification
Hi Richard, the diffusion frames you see in some of these videos are flat aluminum frames that I ordered from Norms Studio Equipment. You can order similar frames from American Grip, Modern, and Matthews. They can be ordered in standard or custom sizes. The ones I have are 2'x2', 2'x3', 3'x3', and 42"x42". Most trucks have 4'x4' instead of 42"x42", but I bought most of my gear to fit in a 1-ton van, so even though I have a 2-ton now, the bulk of the frames are still 42"x42". I've come to really like that size:-) I keep most of the frames skinned with different thickness of diffusion so there are choices readily available. Does that help?
Luke Seerveld Thank You this was a huge help as are all of your videos I watch and re watch them every day you make some amazingly informative content. Thank you very much for all the time effort and passion you put into everything you do it truly shows
Luke Seerveld can u make a video of gear to invest in when starting out
Hi Richard, I'm glad you find these videos helpful. Thank you for the kind words.
Hi Richard, Do you mean someone starting out to be a gaffer or someone starting out to be a filmmaker in general? Getting into gear is not for everyone, but you can't go wrong with a couple of 1x1 Astras by Litepanels... along with two lightweight folding stands, DoP Soft boxes, and some DIY stingers:-)
The model’s eye lids grow heavier and heavier as she falls into a coma with the photo-splaining
😂
Still greek to me.