[alt-photo] Re: gum contrast...

[Katharine Thayer]

Paul, I am literally too tired to think tonight, but I have this  
vague idea that there was a discussion about this on the list a year  
or two ago, and that I may even have done some testing.  I did a  
quick search at the archives but didn't come up with what I was  
looking for.  It seems like it wasn't exactly this question but was  
masquerading as this question, or something like that, but I don't  
remember the discussion exactly.  I'll look again in the morning.
kt


On May 17, 2010, at 4:00 PM, Paul Viapiano wrote:

> Hi all,
>
> Thanks for the comments on my last question. Sodium bisulfite  
> helped restore brighter colors but yes, not overexposing in the  
> first place is good advice.
>
> Riddle me this, sil vous plait: Knowing that decresing dichromate  
> increases contrast, what would be the difference between a mixture  
> of 2:1 gum/dichromate and a mixture of 1:1 where the dichromate is  
> 1/2 strength, both at the same exposure time?
>
> Katherine mentions in her website that halving dichromate reduces  
> speed by approx one stop. If you halved the dichromate, and  
> increased the exposure by two, would you effectively get the same  
> print as a 1:1? I'm trying to see relationships in theory here...
>
> Thanks in advance...Paul
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