Aristo V54 bulb, Zone VI controller, and contrast?
 

I was recently doing some step-wedge testing and noticed
that anything higher than grade 3.5 looked prettmy much the
same. Here are the details:

Zone VI cold light head (Beseler 45) with Aristo V54 bulb, less
than 2 hours total usage I guess

Zone VI intensity controller

Kodal Polymax filters (relatively new, high contrast barely used)

Luminos Flexicon VC (= Kentmere Fineprint VC, I think), both in
fiber and RC, also Forte Polymax fiber

Silverprint Tektol neutral and Tektol standard developers

The Aristo bulb is supposedly designed to work "better" with VC
papers.

It occurs to me just now (that I don't see any available darkroom
time in the next couple of weeks, and being Sunday I can't ask
Aristo) that I normally use my Zone VI controller with the intensity
set at "F" to give me a little longer exposure at f/8. I can achieve
stabilisation typically up to K or L once the bulb is warmed up.

Here's my question - has anyone ever done experiments to assess
contrast grades vs intensity with the Zone VI controller? If so, this
could save me a bit of time and paper; if not, I'll do it myself and
post the results, though it could be a while...

TIA.

Steve

Aristo V54 bulb, Zone VI controller, and contrast?
 

"Steve Goldstein" wrote

I was recently doing some step-wedge testing and noticed
that anything higher than grade 3.5 looked prettmy much the
same. Here are the details Zone VI cold light head
Zone VI intensity controller

I take it you have the ZVI single tube head and the
'cold light stabilizer' box with 'lamp intensity' and
'drydown' knobs.

Kodal Polymax filters (relatively new, high contrast barely used)
Luminos Flexicon VC (= Kentmere Fineprint VC, I think), both in
fiber and RC, also Forte Polymax fiber

Some possible causes:

1) Papers and filters are designed together: Kodak filters for
Kodak papers, Ilford filters for Ilford paper ... I don't know
what filters are best for Forte and Luminos [And Luminos can
be _anything_, though if marked UK then it is probably
Kentmere]. I would suggest giving Ilford filters a try.
Looking at Forte's web site may give recommendations for
filters.

2) Old paper looses contrast. Paper can sit on a dealer's shelf
for years.

3) Cold light heads will shift spectrum with temperature, try
leaving the enlarger on for 1/2 hr before printing.

4) Cold light heads and VC papers have never gotten along very
well. However, the problem is usually that no low grades can
be achieved.

5) Try developing for 5 minutes. VC and many graded papers
are made from two or more emulsions with different contrasts.
If the high contrast emulsion isn't developing fully then the
print looses contrast though it may have full blacks. Try
Dektol 1:1 as a check. Some papers and some developers
have trouble developing fully: Forte and Arista developer
are a bad combination - after 5 minutes the paper still
hadn't developed fully. Forte graded will take 5 minutes
in D-72 [Dektol] to develop to completion.

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.nolindan.com/da/index.htm
n o lindan at ix dot netcom dot com