Re: HP5+ and LONG development times

Shannon Stoney wrote:

> I am shooting HP5+ in the 8x10 format in a pinhole camera for cyanotypes. I
> am having trouble getting the highlights dense enough. I am up to a 20
> minute development time now, and still the highlights only have a density of
> 1.71. I would like a density range of about 1.6, starting at 0.35, say, in
> the shadows. (I have to shoot it at like 3200 to get the shadows this
> thin!)

How are you reading the densities? I sometimes see students of mine make
mistakes and zero out our old densitometer to straight white light from
the reading arm. Then when they read the shadows they don't take into
account the subtraction of base plus fog from their readings. To
automatically do this I zero my desitometer out on my base plus fog
area. Then the shadows read correct. What makes me think this might be
your problem is that base plus fog for HP5 is about .35 anyway and you
said you had to shoot at -3 stops to get it there. Sounds like something
is fishy with your measurement procedures.

Thinking about your -3 stop exposure makes me also wonder if your camera
might have a light leak or a flare problem. This would also cause a
reduction in contrast and difficulty in achieving low shadow densities.

Let me know how things turn out. I haven't made direct negatives for alt
printing and have wondered how much development would be necessary for
the figures stated in the books.

-- 
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Chris Peregoy | http://www.gl.umbc.edu/~peregoy | http://imda.umbc.edu/