Advice on using Spot Meter for shooting....

[grantw]

I'm trying to learn more about the spot meter and how to expose things better through it. I've talked to people and they've mentioned how to put things like highlights, shadows, and other lighting aspects you want in certain percentages. Are there any articles or anything to help know generally what percentage you put different things at for basic exposure?

Thanks.

 

[Jason Davenport]

The spot meter measures reflectance values. With film I would find a exposure I wanted for the actors say f2.8 then use the spot meter for, lets say a window. With film you know you can go four stops over your f2.8 (because film can handle highlights better)so the window would need to be right under or at f11. Anything over that would be blooming and overexposed. So when your lighting a scene, you use your spot meter to check all of your "hot spots". With video you don't have the range that film has so you want to control all of those areas. Just think of it as a hand held "zebra" meter. In video you don't want any of your highlights going above 95 ire, on the waveform. It's a little tricky with video, you need to know your camera ASA rating for exposure. Most HD cameras are rated at about 320 ASA so you would set your meter to 320. Use your incident meter to light actor, say at 320 ASA at stop of F4 would put your actors face exposure at 65 IRE. so then you use your spot meter to measure all the "hot" areas and keep them at or under 2 stops over your F4. I for get the range but if you have a waveform and a meter you can see what your doing. A waveform is a must, period, with HD.
By adjusting your Fstop and metering with spotmeter your just trying to keep your "hot spots" under 95 IRE on the waveform.

You just have to figure out on the shoot day what easier to control with the tools you have, the actors key or whatever is going to be way too hot. Lets say, you have one scene that has a lamp with no shade in background, that's easy you just dim the bulb or spray "streaks and tips" on the bulb until you get the desired stop needed to stay below 95 IRE, and keeping your exposure for your actor to 65 IRE or whatever. If you have a very large window and a large lighting package, you can stop down the camera to get the correct exposure for the window, which could be at F8/11 to keep it below 95. But now, you will need a lot of light to now bring your actor up to 65 IRE, hence a 1200 HMI or 4K HMI.
It's a lot easier to bring down what's hot then to bring your actors keys up and cook them with and instrument.

http://www.lafcpug.org/over_under_expose_video.html
http://provideocoalition.com/index.php/freshdv/story/calibrating_a_light_meter_for_digital_video/