Light meter question for a DOP

[rc444]

I did a lighting test at film school. I was filming a film noir scene and used a light meter.

The shoot was fairly straight forward. One scene. A curtain in the background, an actor playing a gangster in the foreground sitting at a table. We used a 2K as they keylight and a couple of red heads as the fill and background.

The light readings for the lights were:

Key: 2
Fill: 2.8
Backlight: 4

We shot on slide film on a still camera, as this will be played on a projector downstairs. We don't get the "rushes" till next week. I exposed for the backlight. As this was film noir, I didn't want so much emphasis on the key, or the visible details on the actors face. Questions:

- The camera's aperture only went as high as 3.5. That's as open as it goes. If you chose f4 as your final aperture (based upon the above information), would the still camera still read it as f4 (even though it only "goes" to 3.5?)

- If you wanted to bracket for +1 (say f 2.8 - 1 stop exactly above f4), would you have to increase all lights to compensate for this. In other words, the key would have to go from f2, it's original setting, to f1, the fill from f2.8 to f2 and the backlight from f4 to f2.8. Would this be right?

 

[Andrew Brinkhaus]

Yes, your camera is going to expose the frame at the stop you selected to shoot at, in your situation, an f4. In doing this, your backlight will come back as medium grey, and your fill will be one stop underexposed, your key side two stops underexposed. Looking back at your labeling, it brings something up. Right now, your key is darker than your fill, which makes it your fill, and your fill your key. You may have dedicated that light to be your key, but it being darker than your fill, automatically reverts it to your fill. Now, as for the bracketing, in order to bracket 1+/1- you would have to either replace the lens, with a faster lens, or relight to 1 stop hotter on your backlight, key and fill.

Now, your backlight would read as an f2.8, your key would read as an f2, and your fill would read at an f1.3 (not actually an f1, as an f2 is generally followed by an f1.3, or similar.)

Hope that all makes sense.