Reading/metering light - a little help?
Posted 07 February 2008 - 04:45 PM
I just wanted to double check that I am on the right track in terms of exposure and light meter readings. I've done this a few times but I think I've just confused myself and wanted someone to clear me on it.
When taking a reading of a face you take an incident reading from both sides (to establish a desired key to fill ratio) and then point the meter to the camera and take a reading to establish the aperture to place on the camera.
When does the spot meter come in? Is it best to use to figure out the background and the such? Or is it better to take a reading of the face with a spot meter?
For example, if you are shooting a figure with rim lighting (basically seeing only their outline as they sit in a chair facing the camera), would you take a spot reading from the shoulders to determine the exposure? And does the gray card come in for this reading, or would it be best to leave it for the a facial illumination?
Posted 07 February 2008 - 05:53 PM
Taking a reading with the meter pointed towards the camera may give you an mean reading of the light and dark regions, allowing you to expose somewhere in the middle.
But what if you want the key side to be at the middle of the exposure, or perhaps you want the key side to be really hot, and the fill side to be just a bit under?
In your second scenario, if you want a silhouette with a hot rim light, why not meter the dark side, and, exposure a few stops under that, to get your subject in silhouette. then meter the back light (with the meter on touching the subject's back, but faceing the lamp) and decide how many stops over you want it.
A spot meter is great for 'checking' particular areas to see just how hot they are, but if you don't really know what 3 stops over will mean on your negative, it won't really tell you much.
A spot meter also takes into account the lightness of reflectivity of a surface. Sometimes its helpful to know just how white that white shirt is going to be.
Convention is no substitute to making your own decisions.
Posted 07 February 2008 - 06:56 PM
Lighting ratios I don't meter for, unless I know I am getting close to Dmax or min and want to know if there will be detail left in the shadow/highlight. spot meters is sort of like a waveform monitor for a single pixel, to make an analogy to the digital realm. They take into account the light that will actually hit the emulsion from that specific point in frame. I don't set appeture by it, but if theres a shine off something then generally its good to spot it to see where in the curve it will lay.
I also use light meters for digital (not sure if your talking film exclusivley or both) but for me it seems like I don't get the camera set until lighting is almost done (esp when dolly/jib/steadycam is concerned), and so I don't have something to look through during lighting. It helps to know your getting to exposure and won't have to throw a scrim in every light, or switch units out if you find you haven't gotten to key yet. Also in digital its tempting to light by the monitor, but honestly, sometimes its a pain to walk all the way back to the video village to check, and no monitor on set is ever truely accurate. So if you know what your camera or film stock can handle, good meter technique can give you a very good idea of where exposure will fall for any part of frame, even if you never metered that particular area.