Re: [Leica] Print Development Time

["Dan Post" <dwpost@email.msn.com>]

Alan-
B&W, of course!
True regarding coldlight heads, but I use the tungsten or halogen lights, so
I can't say for sure.
I've never noticed a significant change in the aging of the bulb of my home
enlarger.( whereas, as a bulb ages in a color printer, commercial that is,
you gradually get longer print times and use less and less yellow
filtration!- that's why we change the bulb about every six months or so
whether it fails or not!)
As far as temperature goes, the two minute time, with gentle rocking of the
tray for agitation, at 68 degrees F. has the same affect as 2 minutes at 80
degrees. I would only be concerned with fog at these high temps.
So far, things have worked out pretty good!
Dan
- ----- Original Message -----
From: A. Huntley <prasepe@ibm.net>
To: <leica-users@mejac.palo-alto.ca.us>
Sent: Monday, August 09, 1999 7:12 PM
Subject: RE: [Leica] Print Development Time


Dan,
You didn't mention B&W or color work...I am assuming B&W.  There are many
variables to contend with here:
1) If you print with coldlight, there is a phenomenon known as coldlight
drift; this causes the light output to vary based on factors such as ambient
temp, light tube temp, etc.  This is why Aristo and others install
thermostatic heaters in their heads as an attempt to minimize the drift by
keeping the head at relatively the same temp for each exposure duration.
2) How much does your darkroom's ambient temp change during a printing
session?  Changes in air temp will, of course, cause the developer to
heat/cool causing changes in print density.
3) What paper agitation technique do you use?  Many people will argue that
agitation doesn't affect print density results.  Try it!  Drop an exposed
print into the developer tray and agitate infrequently...do another--same
exposure, etc.--and agitate quickly, consistently, and thoroughly.  Compare
the two.  Different is not the same!

I could go on, but the above gives you a few examples.  Solutions?  There
are high-tech answers and very low-tech things one can do.  To pursue the
high-tech road, call Calumet Photographic for one of their catalogs
describing darkroom equipment and look at the stuff Zone VI manufacturers.
They have compensating enlarging timers that put an end to coldlight drift,
and a really nifty compensating development timer that actually adjusts
"clock speed" based on developer or waterbath temp.  I have one of these and
it's really quite amazing.  Prints developed at 55 deg F will look identical
to those done at 80 deg F; and, all will indicate 2 minutes on the timer!!
Puts an end to summer and winter print density variation caused by developer
temp changes during a printing session.

For a low-tech solution, Ansel describes a factor development kind of thing
in, I believe, his Print book.  Can anyone verify this?  If I remember
correctly, this technique involves locking down parameters based on when
certain values appear as the print develops.  All other print development
times will be a factor based on the appearance of these same values.

Hope this helps.  Good luck.

Best regards,
Alan Huntley

- -----Original Message-----
From: D Khong [SMTP:dkhong@pacific.net.sg]
Sent: Monday, August 09, 1999 4:12 PM
To: leica-users@mejac.palo-alto.ca.us
Subject: [Leica] Print Development Time

Friends

Presently, I am assessing the developing time for my prints visually.  If I
want to produce two prints of similar nature this method may not be perfect.

I will appreciate your feedback as to how I might achieve better
consistency.

TIA.

Dan K.
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