Aristo cold light head

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seldomseensmith
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Aristo cold light head

Post by seldomseensmith »

I recently purchased an Aristo D-57 cold light head to be used with my Durst L138S enlarger. I've never used a cold light head before, so I have some questions for someone with some experience with this kind of printing. First of all, is it better for me to used graded paper vs. variable contrast paper? Also, is it essential for me to have a stabilizer to go with this cold light head? I don't have one, but I live alone in my house, so there isn't much fluctuation in the use of electricity. Also, how long should I let the thermo unit heat up before I use this head? I've heard anywhere from no time to 15 minutes. Besides these questions, if you have any other tips and tricks about using an Aristo cold light head, I would appreciate it. I'm planning on mainly printing panoramic medium format negatives from a Linhof Technorama 617s III camera. Thank you!
tim.bowman
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Re: Aristo cold light head

Post by tim.bowman »

I won't pretend to be an expert here, but I have used a cold-light adapted Omega D2 for a while. I never owned a stabilizer and didn't see a need for one in my printing. I have used both graded paper and variable-contrast and both work fine.

My thermo unit switch doesn't have an indicator light on it, so sometimes I print without remembering to turn it on. Things seem to turn out okay without it. That said, I print slowly and keep my exposures around 20 seconds, so I do't think I'm building up much heat. With the thermo unit on, you can feel when the unit is "warmed up" by touching it. Mine doesn't get very warm, just pleasantly so. I imagine 15 minutes would be plenty of time.
seldomseensmith
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Re: Aristo cold light head

Post by seldomseensmith »

Thanks for the helpful information.
Colorado4x4
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Re: Aristo cold light head

Post by Colorado4x4 »

I use the cold light head & also I have a 40Y gelatin filter with Ilford MG paper (recommended by Ilford. I also don't know why graded papers would be a problem. Today I was testing my printing & failed to turn on the light source but it seemed to be OK.
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sanchell
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Re: Aristo cold light head

Post by sanchell »

I did the testing and evaluation for the D-57 head for Aristo. It was intended for use with VC papers. The D-55 had an equal balance of blue/green phosphors. This combination worked well with graded papers but required the addition of a green filter to work with VC.

The D-57 has 30% blue and 70% green, as I recall. However, as every manufacturer has a different VC formula for their paper, it still needed to be tweaked to more closely match Ilford, or Kodak, or Agfa, papers. So Ilford's recommendation is probably a good one.

That said, the thermo unit is meant to help stabilize the light. It is not entirely necessary. In 50 years of printing I never used an image stabilizer. My personal "guess" is that in the early days of enlarging, electric codes were not as stringent, wiring, outlets, were not as well made, etc., and voltage fluctuations could be a problem if one occurred in the middle of making a print.

You can test the grades of your VC paper using the methods found in The Variable Contrast Printing Manual.

As far as it goes, a 20 second printing time is a good target with modern emulsions, as Tim Bowman suggests.
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hmgolds
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Re: Aristo cold light head

Post by hmgolds »

Colorado4x4 wrote: Fri Feb 05, 2021 4:57 pm I use the cold light head & also I have a 40Y gelatin filter with Ilford MG paper (recommended by Ilford. I also don't know why graded papers would be a problem. Today I was testing my printing & failed to turn on the light source but it seemed to be OK.
A couple of years ago I set up an enlarger with the earlier Aristo head. I had difficulty finding a 40y gelatin filter, but was able to find an inexpensive 30y Rosco filter at a local theatrical supply house. Worked reasonably well - was able to get 5 grades though were not as linear as I would like.
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sanchell
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Re: Aristo cold light head

Post by sanchell »

The purpose of the D-57 was to get the grades to be as linear as possible. It, too, was not perfect but we got very close, tweaking with the appropriate filter, and Roscoe was the filter mfr. of choice, got it even closer with specific papers.
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