U of S | Mailing List Archive | alt-photo-process-l | Re: Gum calibration (was: Paper negatives- Ink Selection)

Re: Gum calibration (was: Paper negatives- Ink Selection)



Hi Mark, thanks for chiming in. See the end of the message...

18 Ekim 2008, Cumartesi, 10:51 pm tarihinde, ender100 yazmış:
>
> ... the density range of the negative does not affect the exposure.
> Exposure is still merely dependent upon the UV density of the substrate
> you are printing on.  Once the exposure is determined, then you just match
> the density range of the negative to the exposure scale of the contrast
> mix you are using.  If, for some reason you have a fixed density range in
> the negative, say from using all inks to make a "grayscale negative", then
> you must alter the contrast mix so that its exposure scale matches the
> density range of the negative.  If you end up with a density range that is
> too high, your highlights will be blown out.  However, if you try to bring
> tone into the highlights by increasing exposure, you end up over exposing
> the shadows and blocking them up.  What should be done in this case is to
> either increase the exposure scale of the contrast mix (by adding more
> chromate) to match the negative or reduce the density range of the
> negative, as you have suggested, to match the exposure scale of the
> contrast mix.

Very true... But ideally. (Assuming the worker is doing it according to
the ideal.) If you're not doing it according to the ideal (such as: not
using a process adjustment curve - or any other means to translate linear
source image tones to the characteristic curve of the target process - to
start with...), then the practical consequence would be DR affecting the
exposure, because you'll naturally expose for the highlights (since nobody
will be interested in a print with blown highlights, with
in-negative-midtones converted to in-print-highligts), and live with
shadows that you get. This is my opinion on what is probably happening
here...

Thanks again,
Loris.