[Morgan Montague]

I, for one, find this an awesome thread here in RAMT. It is this sort of
minutea (meant in a good way) that keeps me coming back day after day. It's
the details that somehow always get f'd up in recording the history of
technology where you wind up with some of the most incredibly moronic press
releases, books, magazine articles and documentaries.

Thanks for all the serious questions and intelligent answers to this
discussion.

Morgan

"Early Film" wrote in message
...
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