ASA question

[Barry Green]

This is a question that has either a very complex answer, or a simple answer.

Simple answer is: 640 ASA/ISO in progressive-scan. But don’t rely on a light meter to set exposure. The speed setting varies depending on where you are in the exposure curve — at lower light levels the camera responds as 400, at higher light levels it responds at 800, but over most of the curve it’s 640.

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Get the most from your DVX camera. The DVX Book and DVX DVD are now available at https://www.dvxuser.com/articles/dvxbook/ and at Amazon (https://tinyurl.com/54u4a)

[Sleeping Beauty]

Hey Barry thanks for the post, very helpful. If I may ask…so how do recommend setting exposure just by eyeballing it? I’ve been curious about the ASA mostly for maintaining light ratios relative to the stop I was using…are you saying the camera makes an automatic gain adjustment in low and highlight situations? Is the 640 ASA reliable if I try to keep the iris in the middle by using ND’s and/or more light? Also does the DVX expose better in the middle I like to avoid gain as much as possible.

Thanks

[Barry Green]

Don’t try to base exposure on “eyeballing”, use the zebras. The zebras will give you a far more accurate measurement of your actual exposure than relying on a light meter will. Light meters work excellently with film, where the exposure curve is flat and linear, but on video it’s not perfectly linear, so a light meter becomes more of a tool for reference but not for critical exposure-setting. For maintaining ratios, as you said, that’s a perfectly appropriate use of the light meter on a video shoot.

In video a waveform monitor gives you far more information about your exposure than a lightmeter would, or even a properly-calibrated production monitor. The waveform lets you see exactly what your signal is doing, what levels you’re shooting at, how your highlights and shadow areas are being handled, etc. The waveform is to video, as the level meters are to audio.

I found 640 pretty much across the board, it was only under the very brightest and very darkest conditions (conditions calling for f/2.8 or less, or f/16) where the variance crept in. And even then, it wasn’t much — about 1/2 stop on the dark end, and 1/4 stop on the bright end. So yes, 640 is a pretty reasonable level to use (note: that’s for progressive-scan mode; the camera is a stop faster in interlaced).

—————–
Get the most from your DVX camera. The DVX Book and DVX DVD are now available at https://www.dvxuser.com/articles/dvxbook/ and at Amazon (https://tinyurl.com/54u4a)