[Early Film]

Karl Uppiano wrote:

How did they compensate for the non-linear characteristic of the emulsion in
VD tracks?

By putting the exposure in the straight line portion of the H&D curve on
both the print and on the original negative, while keeping the print
thin enough to still play properly. The difficulty of getting this
correct was the reason for the demise of VD tracks. Most modern labs
simply don't want to waste time learning how to do this with sound,
although they do it with picture all the time.

It seems that VA would be more linear, since it is strictly a
geometric, not a photochemical transfer function. Am I missing something?

Yes, you are missing something.

In VA, you have image flare in the stock and that changes the shape of
the sound waveform. In VA, this happens in both width and in length.
In VD, it only happens only in length, so there is less likelihood of
that problem causing distortion, plus in VD you are recording a lower
contrast signal, so there is less flare to begin with.

In VA, since you have much more flare in the print stock than in the
negative stock, one has to greatly overexpose the negative to
intentionally get flare to cancel out the flare in the print.

Karl, I would have dropped the cross-posting, but I don't know which
group you are reading.

Earl in Rec.Arts.Movies.Tech