From: bjs@uts.amdahl.com (Barry Sherman)
Newsgroups: rec.photo
Subject: B/w papers and developers (longish)
Date: 6 Jan 93 01:23:47 GMT
Reply-To: bjs@amdahl.uts.amdahl.com (Barry Sherman)
Followup-To: rec.photo
Organization: Amdahl Corporation, Sunnyvale CA


I got curious about some things and did some quick and dirty testing last 
night.  Money's somewhat tight right now and I was questioning my decision
to use only 11x14 paper and to cut 8x10 sheets from it.  I've been doing so
to ensure using the same emulsion batch so as to simplify the transition from 
8x10 work prints to 11x14 final prints and have found it to be extremely 
helpful in Cibachrome printing.

But I have about 200 sheets of 8x10 Ilford MG b/w paper and it seems wasteful
to let that paper languish if I don't have to.  So I thought that I'd check to 
see just how different the 8x10 emulsion is from the 11x14 emulsion with an 
eye toward developing an algorithm for changing exposure and (VC) filtration 
when moving from 8x10 work prints to 11x14 final prints.

Testing was done by projection printing a 10-step step tablet onto smallish
sheets (4x5) of paper.  I found the exposure which caused the lightest
step(s) to blend into Dmin and which caused the darkest steps to blend into
Dmax.  Then I used my old Kodak Visual Densitometer to read densities on
the first steps which were distinct in the whites and in the blacks.  This
analog densitometer requires visual comparisons and isn't super-accurate
but I've satisfied myself that it gives results repeatable to +/- ~.02 log
density and I consider that accurate enough for casual use.  (I.e. 
absolute denisities may or may not be terribly accurate but relative results 
should be meaningful.)

In addition, my 10-step step tablet isn't as sensitive to exposure changes as 
would be a 20-step one, but my results with it are acceptable to me.

Development was in Ethol LPD diluted 1:2 for 2.5 minutes at 20C.

So, having determined the best exposure with the 8x10 paper I then made
an identical exposure onto the 11x14 paper.  The first thing that I noticed
was that to the naked eye they looked absolutely identical.  After drying
I read densities as described above.  

                                          8x10               11x14
                                          ----               -----

  Density of lightest distinct step:        .1                 .1
  Density of darkest distinct step:        2.1                2.13

I concluded that differences are so slight as to be immaterial.  I think I'll
go ahead and use the 8x10 batch for working prints and then switch to the
11x14 for final prints.  If there is some subtle difference, it should be easy 
enough to correct.  When I run out of the 8x10 then I'll return to cutting 
8x10's and test strips from the 11x14.

Then I thought about a comment that I recently heard to the effect that John 
Sexton thinks that there's very little difference between paper developers.  
So I did some more tests.  Same exposure onto the same paper, but I developed 
one sheet in Dektol 1:2 and one sheet in Zonal Pro Factor One 1:15.   
(Obviously, I've been dithering about which developer to standardize on ;-)

I developed in Dektol for 2.5 minutes at 20C and in Factor One for 3 minutes at
20C.  LPD and Dektol both recommend development times of 1.5-3 minutes while 
Factor One recommends a somewhat longer time at 2.5-3.5, hence the longer 
development time in Factor One.

                                       LPD         Dektol      Factor One
                                       ---         ------      ----------

  Density of lightest distinct step:    .1           .1            .08
  Density of darkest distinct step:    2.1          2.1           2.15

I could detect no significant difference in color (warm tone or cold tone) in 
the test strips.  Probably color would be more noticible in a real print,
though.  But I think that the obvious conclusion is that there is no
practical difference between these three developers.  This is somewhat 
surprising.  I'd expected fairly significant differences in contrast and
density.  But the results were so similar as to be indistinguishable to
the naked eye.  And hardly distinguishable to the densitometer.  When I
finish the print that I'm currently working on I think I'll try developing
versions in each of the developers to see how/if they differ in the more
subtle arena of a real print.

And in addition, since I'm already flapping my gums, so to speak :-), I've
been having good success using a "kinda pseudo-replenishment" scheme with
b/w paper developer.  I like to use largish amounts of developer in largish
trays and really can't afford to be throwing out a gallon or so of working
strength developer at the end of each printing session - 3 or 4 nights a week
when I'm doing b/w.

I've been measuring the volume of developer after each session and have found 
that the double-weight fiber-based paper that I use soaks up a very significant
amount of developer.  A session in which I develop 15-20 or so 8x10's may 
deplete the volume of developer by 8 ounces or so.  If one is re-using the
developer this can significantly reduce the volume of chemistry available
after only a couple of sessions, compounding the deleterious effects of
developer exhaustion.

So I've been measuring the volume of my Ethol LPD after each session and 
mixing and pouring in enough working strength to return the volume back to
one gallon.  I then store the developer in a one gallon accordian bottle.  

This seems to have a replenishment effect.  Every 10-20 prints I've 
tested the developer by making an exposure of whatever I'm working on
on a small test strip and developing it in a few ounces of fresh developer.
When the strip developed in fresh developer no longer exactly matches that
developed in the "used" developer, I'll throw out the used developer.  So far
I've developed 75 prints in "one gallon replenished" of Ethol LPD over the
course of about 1.5 weeks and, while it's pretty brown, the test strips still
look the same.  Unfortunately, there was a small accident last night and
I had to mop up most of the LPD.  (Damn cat! :-)  But I'll be restarting and 
continuing the experiment.

BTW - although I do frequently take issue with the way that Mr. Picker
says things, he really is right about "try it find out for yourself".  Although
maybe I'd change it to "try it and find yourself as much as time allows".  In 
fact, it's through that process that I'm coming to disbelieve his maxim:  
"Never pour anything back into a bottle" as applied to paper developer.  If 
tests developed in fresh and "used" developer look the same then he's just 
plain wrong (and yes, I'm getting nice inky black blacks).

Barry
-- 


|----------------------------------------------------------------------------|
| Barry Sherman, Amdahl Corp. | "It's much easier to go to exotic places and | 
| bjs@uts.ccc.amdahl.com      |  capture spectacular scenes than to take a   |
|                             |  spectacular picture of a really boring      |
|                             |  green pepper". - Anthony Tse                |
|----------------------------------------------------------------------------|
| Amdahl, being a corporation, is a legal fiction.  Therefore it is incapable|
| of holding, let alone expressing, opinions.  Unfortunately, this has been  |
| said of me as well. (I.e.  My statments are mine, not Amdahl's.)           |
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