[Alt-photo] Re: GUM: problematic yellow?

[Luciano Teghillo]

Now I am a bit confused. I thought I was supposed to merge step 1 & 2, and
then calculate the difference between the base of the Stouffer step wedge
with the Pictorico base (multiply the time found by 0.9 and divide the
result by 0.7). So I should choose the time from the last strip printed
where step 1 and 2 do NOT merge? and then use this time to calculate the
difference between the two bases?

Houston I think I have a problem here :-)

Luciano


-----Original Message-----
From: alt-photo-process-list-bounces at lists.altphotolist.org
[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
Alberto Novo
Sent: Thursday, February 06, 2014 2:15 PM
To: alt-photo-process-list at lists.altphotolist.org
Subject: [Alt-photo] Re: GUM: problematic yellow?

Yes for the minimum exposure time (the value which gives you the maximun
"black" without merging steps 1&2). But if you will find that the amount of
color is too much or too less, and you will be forced to modify the % of
pigment in the mix, you have to find the new minimum exposure time because
the pigment itself acts as a self-mask to UV. This depends on the pigment
and cannot be generalized (UV absorption is independent on visual density). 

Alberto 

>  
> I think that when I start layering the colors I will have to make 
> other adjustments, either to the exposure time, color mix, or 
> negative. But for now I was wondering if for blue I should use an 
> exposure of 2 minutes (as indicated by looking at the color page) or 3 
> minutes (as indicated by looking at the grayscale version). In 
> summary, are you suggesting that is best, as a starting point, to 
> evaluate the exposure time by looking only at the grayscale version?
> 
> Luciano
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