Canon A1 ASA / ISO Rating?

[Brian Spatz]

I'm not sure if many will find it useful, but I was wondering if someone has come across the A1's ASA/ISO equivalence. I was trained lighting for 16mm and I have a Sekonic meter that I would like to use, however I don't know what to set as the equivalent ASA.

I was reading Barry W. Green's "The HVX Book," which as you could have guessed is based around the HVX200. However this book goes into things like 24f strobing issues, pan timings, shutter speed/angles, frame rates, pulldown ratios, etc. Even though I don't own a HVX camera, I would recommend skimming through the first part of the book. He writes that at 24p and 1/48 shutter using "HD Norm gamma," that camera responds to light at about a 320 ISO film stock.

Does anyone have any information on the A1's ASA equivalence.

Thanks in advance.

[Don Palomaki]

ISO/ASA is not well defined for camcorders because the CCD/camcorder system respond differently than film. Also, light meters are not often uses because the camcorder is itself a light meter of the best kind (on the monitor you can see the exact exposure of the entire image in real time so you can adjust exposure (and/or lighting) to you taste for highlights and shadows. (Can't do that with film because you have to soup it first, which is why you have to have light/exposure meters.) Further, you have three major exposure parameters to adjust with the camcorder (shutter, aperture, and gain, ignoring gamma, etc.), not just two as with film cameras. In film speak, gain is somewhat like push processing, with 6 dB of gain corresponding to a stop of exposure.

That said, light meters can be an aid when setting up a set before the camera and monitor arrive. As a rough guide, ISO/ASA 320 (give or take a stop) is consistent with figures I've heard, for 0 dB gain for many of the 3CCD Canon camcorders. But if you plan to use a lght meter with your camcorder, run your own tests with the camcorder to determine what settings produce the results you want. Set-up a scene with the desire lighting, adjust the camcorder for the image you want, check the gain, aperture, and shutter. Then meter it and see what ISO corresponds to the settings at the selected aperture and shutter. Repeat for other conditions of interest and see how the ISO varies. Keep records for future reference, and please share you results with us.