Cold light for VC papersgreenspun.com : LUSENET : Large format photography : One Thread
I just acquired an enlarger with an Aristo cold light head. When I wanted to buy variable contrast paper (to use it with filters below the lens), the salesman told me it would not work with a cold light head. Is this true? Are there diffiulties to use VC paper with a normal cold light head?
-- Lukas Werth (email@example.com), April 30, 1998
It's not that it won't work, just that it won't work as well. The cold light will produce a strong grade 3, with the average VC paper, whereas a tungston light will produce a normal grade two, with out a filter. This has been my experience at any rate. The filters will change the contrast, but a grade 0 filter may only allow you a grade 2 hardness with a cold light. It is also much slower to print with a cold light and filters, and the image on the easel is much darker. Obviously, hard contrast is much easier to get, and the softer contrast can be addressed by the use of Selectol Soft developer, in conjunction with your normal developer.
It is more difficult, but not impossible to use a cold light and filters, but if you are realtively new to darkroom work and enlarging it might be less confusing if you started with graded papers and got a feel for the processes first. Just a suggestion, but I have done ot both ways, and graded papers and a cold light was a pretty easy combination to use to master the basic enlarging techniques.
-- Marv Thomspon (firstname.lastname@example.org), April 30, 1998.
If you use the "old" cold light tubes, with very heavy blue spectrum, you'll get fairly high contrast. You may be able to use new tubes if your head was made by Aristo. Try not to use filters under the lens-this is another chance to get spots, scratches, etc on your prints.
-- Luis R. Ramos (email@example.com), April 30, 1998.
It is impossible for anyone to say what grade or grades you will get with a cold light head and variable contrast paper because that will vary from paper to paper. I assume you are aware of the fact that you filter numbers (1, 2, 3, etc.) don't correspond to paper grades. I have used the Aristo VCL 4500 cold light head for years with all sorts of different variable contrast paper and have never encountered any peculiar problems.
-- Brian Ellis (firstname.lastname@example.org), May 01, 1998.
The "old" Aristo heads produced a large amount of blue light and with a lot of papers produced a grade 3 or higher grade. The newer tubes produce a lower grade. Therefore, it may be impossible to say that a head will produce a specific grade of all papers but heads that produce a lot of blue light will make the paper have a higher contrast, everything else being the same
-- Luis R. Ramos (email@example.com), July 11, 1998.
The salesman you talked to was incorrect. Even with the blue spectrum cold light lamps that are optimized for graded papers you can get excellent results. I did for many years. If your lowest contrast filter won't give you the results you need, try adding a 40cc yellow filter. You can put in in the cold light above the diffuser. But, only do this if you can't get the results you need with your lowest filter. Do not leave it in all the time as some recommend. The reason is that a yellow filter blocks the blue light of the lamp making printing times very long. The best thing to do, however, is to replace your existing lamp with the new V54 lamp which is designed for use with VC papers.
-- Tom Johnston (firstname.lastname@example.org), November 25, 1998.