U of S | Mailing List Archive | alt-photo-process-l | RE: Gum tonal range and linear response

RE: Gum tonal range and linear response

Marek, I think you had mentioned that before, but I somehow forgot about

Thanks again for another useful tip; I will definitely try this if I come to
a situation that calls it. I use digital negatives (but the curve is from
cyanotype) and I usually don't have any problem with highlights, only
occasional underexposure which is pseudo-fixed by developing less (I don't
like this but will do it if I need). May switch to give short flash
exposures in future prints; I can certainly use more robust (but not
stubborn!) layers in development, especially if I plan to intervene by hand.

What is your upper and lower limits for flash exposure? (Please include info
about the base exposure too, to let me compare.)

Thanks again & regards,


From: Marek Matusz [mailto:marekmatusz@hotmail.com] 
Sent: Tuesday, October 13, 2009 4:43 AM
To: alt-photo-process-l@usask.ca
Subject: RE: Gum tonal range and linear response

I just thought about the whole linear/non-linear response of gum and now I
think that my method of exposing gum for some time and then flasing it with
straigh UL light (no negative) for a short time period (seconds) which
results in a very nice extension of highlight detail, is an old-fashined way
of curving otherwise linear Stouffer step tablet. Maybe somebody saavy in
Potoshop could work out a curve that corresponds to this physical
manipulation. It really works miracles to reveal highlight detail of dense
negatives. It adds little exposure to shadows that have already been exposed
a lot, but changes highliths a lot, since it adds a significant exposure
there. Great for those palladium negatives that you never though could be
printed in gum.