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Old November 25th, 2008, 08:37 PM   #1
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Light Meter

Hi,
Can someone teach the basics of using a light meter for use with HD video? I am a total noobie with this stuff.

I was looking at this cheap one to get started:

Amazon.com: Sekonic L-308s Light Meter (Black): Electronics

Is this even a necessary tool for me to master, or should I just use the LCD and use zebra stripes?
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Old November 25th, 2008, 10:09 PM   #2
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Personally, I love using a light meter with digital video. It's an invaluable tool for a number of reasons (in no particular order):

1) Location scouting - don't need to lug a camera around with me. I figure out beforehand how much light a particular camera will need to get an exposure. With my meter on the scout, I can figure out how much lighting I'll need to have standing by to make good pictures.

2) Ratios and set lighting - When I do multi-camera jobs (or a setup where I'm moving between multiple subjects with their own lights), I can get all of the key lights even and everything will be totally consistent camera to camera, shot to shot. Same goes for coverage and changing lighting setups for closeups and such. For ratio stuff, I know I'm going to expose for a particular thing, be it the subjects key light in an interview setting or maybe a set of windows or whatever, and I use the light meter to get everything lit the way I want (IE if I'm exposing for the subject's face and I want a window to be 2 stops over).

3) Greenscreen - just hold down the button and walk the screen. It's a VERY easy way to make sure everything is even. Sure, one could open up on the iris until the zebras are visible and then make it work, but to me it's easier to just use the meter.

I've never been interested in "rating" video cameras because I've never been happy with the results. There are too many factors, too many settings and stuff to really accurately determine an ISO. So I don't use my meter for figuring out my stop - that's what the zebras are for.

As for a particular meter - don't spend a lot. I use an analog one (with the needle), the Sekonic Studio Deluxe II. If you know you'll be shooting a lot of film, then maybe you should consider investing in a better one (the Spectra Cine is damn good bang for the buck at around $400). If you don't see much or any of that on the horizon, save your money. Besides, the cheaper ones work for film too. You just have to think a little more and do calculations in your head on the fly.

Good luck.

~~Dave

EDIT:
Forgot to address the "how."

For consistency between setups (or between multiple cameras), measure your light sources and adjust to match.

For ratio stuff, measure the amount of light on your key (make sure to flag - or turn off - the fill and any other light that might be hitting the sensor). Then, measure the fill and determine your ratio (for example, 2:1). Adjust accordingly. 1 stop over is twice as much light. 1 stop under is half as much light. It goes like that. 2 stops over is 3 times as much, etc.

Stops are useful in figuring out what's acceptable in terms of your medium's exposure latitude. If a camera or film stock has about 8 stops, it means from where you expose, the medium retains detail 4 stops over and 4 stops under. For example, some say that the DVX100A has on average 7 stops, which I believe is 3 stops over, 4 under. If I'm lighting a scene and I measure 60 Footcandles on my key and a window is reading at 960 FC, it's 4 stops over. I know that if I'm exposing for the key, the window is out of acceptable range for my camera. There won't be any detail there. Sure, you can figure this out with a good monitor on hand or even messing around with the zebras, but the meter is lighter and you can walk around with it. If you're a DP with a good crew, you can hang out at the monitor and direct the grips and electrics. If you're the lighting cameraman and you're doing it all, it's a pain in the butt to have to adjust and then run back to the monitor to see if that did the trick.

Last edited by Dave Dodds; November 25th, 2008 at 11:47 PM.
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Old November 27th, 2008, 02:16 AM   #3
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couldn't agree more. a light meter is super useful when lighting a setup where even lighting counts (chromakey backgrounds ! ), especially if there is no camera around to check. I use to light sets in a TV station this way, dead even to .2 stops for all keys. this meant they didn't have to ride iris on shoots because the light was even for all main positions. engineers liked me :)

as for using it to set camera iris, forget it. while I often found the cameras irised within 1 stop of what I lit ( D30's, 1/60th @ ISO 320 ) new modern cameras do so much with DSP processing its a fruitless process. this is especially true once you start to work clipping level ( knee point ) 108 IRE vs 100 IRE, gamma, black stretch, ped . sure, you've read interviews of some nuttywood DP that did exactly this, but if you shoot with a high end camera with 10+ stops of range to a 10bit plus format then you have a modest fudge factor to not get burned and light "like film". you can get away with this, and color correct in post. however you are not making ideal exposures. you need to learn to view on a good monitor, and have a waveform monitor as your best friend if being paranoid.
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Old December 6th, 2008, 02:40 PM   #4
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I was in photography for about 30 years. Everything from hard news to 4x5 studio camera and portraiture.

A light meter was a powerful ally, allowing me to predict what would come out on film after processing.

However, as I went to digital and video, light meters became less necessary. Now, with a good EVF, zebras and a histogram, the camera tells me exactly what it's capturing.

For green screen I set my zebras to 50%. I know instantly what's dead-on and what's not, and exactly where the bad spots are.

I loaned my Minolta III incident flash meter to a friend several years ago and hadn't had to ask for it back yet.
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Old December 9th, 2008, 09:15 PM   #5
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Dean: I still use my Seconic but only for lighting design and location scouting, NOT for camera exposure.

Lighting ratios for interviews are much faster once you get used to reading a meter. You don't need a subject to sit in to know what your final image will look like: it's in the numbers.
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Old December 11th, 2008, 01:20 AM   #6
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Can't say as I agree with that last statement, Shaun. Intensity is only one of the factors that make up lighting, while other factors independent of those "numbers" include quality of light (hard/soft), color, size of source, angle etc. Certainly you can rough in your units and measure the ratios but once the specific subject sits in the chair, everything and anything is subject to change (including the ratios). Each face requires a different approach to look their best, as I'm sure you'd agree.
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Old December 11th, 2008, 03:56 AM   #7
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Figuring out lighting ratios for film sometimes demanded both incident and spot meters. And lighting ratios were different for the various emulsions: VPS was a lot more forgiving than Ektachrome 100. And with the zone system I could make Tri-X give me anywhere from 10 to 12 stops of range. All that stuff had to be in my head and visualized, even when shooting Polaroid tests.

But with video all I need to do is look through the viewfinder and see what I'm getting. Good thing, too, because I usually only have a couple seconds to figure it out nowadays.

I worked with a very talented DP on a feature film last year and she never used a meter. Everything was eyeballed through a monitor and the results were excellent. The great thing about video is that what you see is what you get.

And if it's merely "almost" what you want, you can tweak a bit it in post and get exactly what you want.

Of course it's easier! This is the 21st Century. We're living in the "Future"! :-)
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Old December 11th, 2008, 11:10 AM   #8
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Quote:
Originally Posted by Steve Lewis View Post
Hi,
Can someone teach the basics of using a light meter for use with HD video? I am a total noobie with this stuff.

I was looking at this cheap one to get started:

Amazon.com: Sekonic L-308s Light Meter (Black): Electronics

Is this even a necessary tool for me to master, or should I just use the LCD and use zebra stripes?
If you want to pose round waving a light meter and have everyone think you're the next Vittoroio Storaro or Roger Deakins then the L-758cine is the one to go for. However, unless you're planning on shooting film, you don't need a light meter and I'd advise spending your money on something useful like a DSLR. Learn how to read histograms and videoscopes and you're exposure will always be spot on.
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Old December 12th, 2008, 05:31 PM   #9
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Charles: yes of course you're right in terms of light quality (and also with regard to fine tuning intensity, once we have our subject). I was merely waxing philosophically on getting INTENSITY of lights of known quality into the ballpark before the interviewee graces us with his/her presence, as I ofttimes don't have much time with my subjects. As well, the less I fuss and fidget with lights while they are in the room, the more comfortable they are.

Of course, I always ask ahead of time whether our subject wears glasses, what colour hair they have (for back/hairlight as well as gelling possibilities) and, if I can manage to get a discrete question in to someone who knows what the subject looks like, build and skin tone. If the person is heavy set, I'll usually opt to key the far side of the face instead of the close side, which of course affects back/hairlight placement as well.
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