Hello. I may be getting an Aristo Cold Light for my Omega B-22. I will assume I have to use under the lens filters. Would anyone care to share their experience with them? Is the image compromised compared with the use of above the lens filters? Also, does anyone use a B-22 with a Cold Light source? Comments? As always, thank you.

Francis

-- Francis T. Knapik (fknapik@mail.nysed.gov), October 26, 2001

Answers

I have used under the lens filters and DON'T like them. Anything in the path of light between the lens and paper (including air) will degrade the light. There is nothing you can do about the air. When pristine, above the lens filters are a fair substitute for above the lens filters. But with time they will collect dust and other pollutants from the air. If I couldn't use above the lens filters at home I would switch to graded papers and 2 developers.

R.

-- r (ricardospanks1@yahoo.com), October 26, 2001.

I have several students using below the lens filters with a cold light. Altho it is not the best method they have had good results. They are not interested in graded papers (alas and alack)

-- Ann C lancy (clancya@mediaone.net), October 26, 2001.

It's not very convenient, but you can use above the lens filters with a cold light head. You will need to buy the large filters and cut them to the size of your plastic diffuser. You then place the filter under (or over) the diffuser, but this may take a few minutes each time to remove the head. The actual technique involved varies somewhat depending on which cold light head and enlarger combination is used. You can also place the filter on top of the negative carrier, but you need to make sure you don't stop down so much that the filter is in the depth of focus.

If you want to use a cold light head with VC filters, make sure you get one with the V54 Aristo tube that is compatible with VC. Most of the older cold light heads sold on ebay do not work well (or at all) with VC filters.

-- Michael Feldman (mfeldman@qwest.net), October 26, 2001.

Francis - I have an Aristo cold light for my Omega B66XL, similar to your B-22. I use graded papers, so I'm not concerned with VC filters. However, I do have a neutral density filter under the light head to reduce the level of light so that I don't have to stop down the lens so much. (I like to use f5.6.) I got a sheet of Rosco neutral density filter material (from a stage lighting supplier) and cut a square the size of the white plastic diffuser under the cold light as Mr/ Feldman described. I had a piece of 1/8" thick clear glass cut to the same size to put over the filter, and the cold light rests on the glass. If I were using VC paper, this is the way I would place my VC filters. But, with clean VC filters placed under the lens, you may not see any ill effects in print quality. It's a trade-off of convenience vs. technical perfection.

I work exclusively in 35mm and I love the Aristo cold light. Good luck!

-- Greg Fight (gfight@gate.net), October 27, 2001.

Assuming you use the proper filters, i.e. those designed for under lens applications, which come in plastic frames, and keep them dust and scratch free, there will be absolutely no image degradation as a result. Don't take my word for it; read Chapter 10 of Ctein's "Post Exposure" and, if still not convinced, perform some tests yourself.

-- Sal Santamaura (santamaura@earthink.net), October 27, 2001.

I agree with Sal above, regarding the use of under the lens VC filters. While it may be possible to detect image degradation as a result of using VC filters using some technique, it is undetectable in prints, in my experience. Just try it and satisfy yourself, then don't worry about it. On the other hand, the VC filters may not work well with older cold light sources in which the color balance is very different from the tungsten sources for which VC filters are balanced. I think newer ones are OK, but make sure to check.

-- Tim Nelson (timothy.nelson@yale.edu), October 30, 2001.

You can filter older Aristo cold light heads for use with VC papers. I can't remember exactly but I think it's a CC20Y or so. Contact Aristo at (516) 484-6141 or http://www.aristogrid.com. Once you filter the head, you use regular VC filters to change grades.

-- Tony Oresteen (aoresteen@lsqgroup.com), November 14, 2001.