From: Sandy King (sanking@CLEMSON.EDU)
Date: 11/01/01-06:41:16 AM Z
Clay,
I agree with Witho about the stepwedge. Comparing prints with a
regular stepwedge and one developed in a staining developer is is the
only real way to know how a stained negative will print with a
particular process. If you have access to a color densitometer you
can come close to the printing DR of a stained negative if you read
densities with the blue channel. However, the final DR indicated by a
densitometer is only an approximation to the actual printing DR, and
in some cases could be off quite a bit from reality.
When using any of the staining developers (PMK, ABC+ or Pyrocat)
avoid over-exposure like the plague. The stain functions as an
actinic filter and over-exposure by one stop or more can result in
very long printing times. I base exposures on an incident reading in
the shadow but double the EI of the film's nominal ISO. That is, I
set the ISO of my meter for HP5+ at 640 instead of 320. With this
technique I get full shadow detail but avoid over-exposure.
Sandy King
>You can make an easy comparison by printing a pyrocat developed stepwedge
>together with a standard stepwedge. You will be able to see at what density
>you get a paper white.
>I measure my pyrocat negatives with a deep blue filter, a non standard but
>one that affects most strongly the readings. I also have a halogen lamp
>built in my densitometer. This and also the type of printing technique that
>you will use will affect your readings. But if you standardize them you will
>have a workable set of data for yourself.
>
>Regards,
>
>Witho
>----- Original Message -----
>From: "clay" <wcharmon@wt.net>
>To: <alt-photo-process-l@skyway.usask.ca>
>Sent: Thursday, November 01, 2001 4:36 AM
>Subject: Re: step wedges; POP and gold toner
>
>
>> Sandy:
>>
>> I decided to try your pyrocat HD developer for a batch of negatives that I
>> will use for platinum printing. I normally use D-76 and a densitometer to
>> figure shadow density versus highlight density and then plan the contrast
>> mixture accordingly. Is there any rule of thumb for converting
>transmission
>> density of the stained negatives to an equivalent for unstained negatives?
>> Is the actinic filter effect less than that of a yellow-green rollo-pyro
>> stained negative? I hope it is, because my only beef with pyro has been
>the
>> incredibly long printing times. BTW, I can already tell that the pyrocat
>> handles highlights as well as pyro. One of the images has a lit lamp, and
>> there is NO halation, while the D-76 negatives have a great deal when
>> imaging a similar subject.
>>
>>
>> Thanks,
>>
>> Clay Harmon
>> ----------
>> >From: Sandy King <sanking@clemson.edu>
>> >To: alt-photo-process-l@skyway.usask.ca
>> >Subject: Re: step wedges; POP and gold toner
>> >Date: Wed, Oct 31, 2001, 5:30 PM
>> >
>>
>> >Shannon,
>> >
>> >Much of the previous discussion has focused on making prints. Your
>> >problem appears to be in the density of your negatives.
>> >
>> >That being indeed the case, and correct me if I misunderstood you,
>> >you will need to adjust the exposure of your negatives by rating the
>> >film at a higher EI. I can't tell you exactly how much because that
>> >will depend on several factors, including how you meter, developer in
>> >use and film. However, try doubling or even quadrupling the EI that
>> >you use to meter.
>> >
>> >If the question is merely that the shadows in your prints are too
>> >dense by about two stops, that represents an overexposure in printing
>> >of about two stops, equivalent to a density difference of 0.60.
>> >Reduce your exposures by a factor of .25 or .50. For example, if the
>> >offending exposure is 100 seconds, reduce to 50 seconds to for a
>> >density change of minute 0.30, or to 25 seconds for a change of 0.60.
>> >
>> >With all POP processes the key to good contrast is to keep the
>> >density of your negatives low in the shadows. Anytime negative shadow
>> >density goes over about 0.40 it becomes very difficult to get good
>> >contrast from POP processes because of their self-masking feature.
> > >Lacking a densitometer, a rough guide to 0.35 on the exposing
>> >negative would Step Four on the transmission step wedge (Stouffer,
>> >Kodak, etc.).
>> >
>> >Sandy King
>> >
>> >
>> >
>> >
>> >> A few days ago, I think I read on this list that two steps on the
>> >>step wedge equals one stop. Is that correct? I am trying to figure
>> >>out how to change my EI, because the shadows in my negatives shot at
>> >>320 are about two steps too dense. Does that mean I'm over exposing
>> >>one stop, approximately?
>> >>
>> >>Also: I am printing on Centennial POP. The brochure that came with
>> >>it says to replenish the gold chloride toner after one 8x10 print. I
>> >>cut my 8x10 sheets into four rectangles, so I thought that I could
>> >>tone and fix four of these small prints, one after the other, before
>> >>I had to replenish. But, that doesn't seem to be the case. After two
>> >>prints, the toner is exhausted and doesn't replenish easily by
>> >>adding 6mls of solution A and B, as advertised. I am wondering if I
>> >>should hold all four prints in water and then tone them all at once
>> >>in the gold toner? CAn you do that?
>> >>
>> >>--shannon
>> >
>> >
>> >--
>> >
>>
--
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