A while back when we were having a conversation about push
processing C-41, another list member sent me some pictures and,
more importantly, two strips of unexposed processed film to have
a look at.
The film chosen was Kodak Supra 800, which we thought would be
the closest replacement for the old Ektapress 800 film which
Kodak claimed could be pushed as much as two stops. I did
disprove their claim, at least in my own mind.
The Supra that had been processed normally has a BD+f of .21R/
.52G/ .35B, the Supra that recieved a two stop push has a BD+f
of .39R/ .68G/ .62B. The red BD+f increased by 1 1/3 stops, the
green BD+f increased by 1 stop, and the blue BD+f increased by
slightly under 2 stops.
So, what does this tell us? First, since the increase in base
density wasn't linear, one can expect some cross curves in the
final prints. The prints I recieved with the film strips show
definite problems with shadows turning yellowish red, which is
to be expected from the non linear response to the processing.
There was also a real loss of definition in the shadows, as the
low end of the exposure fell below the threshold value of the
film. As a matter of fact, about the only thing that looks good
is the highlights and upper midtones in the 2 stop push
processed film, which would have recieved exposure in the zone 4
to zone 7 range, and would have been within the exposure range
of the film if processed normally.
William Robb
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