Hi,
I have a Durst 138 with the cls301 colorhead, the enlarger are from the mid 70's.
Today I printed some samples at various grades to use for testing a diy LED head on a Focomat 2c, work in progress.
Looking at my test prints there are very little difference between the grade 3 and grade 5 print from the durst. Had expected a wee more.
Thus the question, do a color head deteriorate with age? Or go out of calibration? (Two lamp head)
Best regards
Morten
If yours has dichroic filters then no. If they have some dupe of died or gel filters then yes, they do.
Morten,
The dichroic filters will degrade with age, and depending on the age/use of the enlarger it can vary. Likewise the age of the bulbs matter; I use to routinely replace the bulb in my enlarger yearly. You can see the difference between a new and old bulb when printing, so you may want to do that first. If you can't get the dichroic filters you can get polycontrast filters for below the lens.
Mike
Michael, Bob
Thank you for the information. The enlarger spent its first 30+ years as a workhorse in the major professional lab here in Norway, before they shut down. Thus it might have seen a large number of negatives probably most color.
Brgds morten
Dichroic filters work through physical filtering rather than by color dyes. Are you SURE they degrade, and by how much? The issue you mentioned was likely caused by the light source, not the filters.Originally Posted by Michael Rosenberg
How did you do the test? Did you verify the filter covers the light source entirely at "Grade 5?" I hope there was no lens involved in the test, otherwise you are testing the lens for flare.Looking at my test prints there are very little difference between the grade 3 and grade 5 print from the durst. Had expected a wee more.
Well, lets rename this from "test" to "reference" :-) the basic idea was to have some comparisons prints from a (assumed) established system vs the new experiment system.
- no I did not verify that the filters covered the light source, I did just dial in the filter settings (130Y/M ilford scale)
- did a teststrip first on each grade, trying to establish the highlights on similar level before the flat print
- both lamps changed within the last 12 months, if this matters. Only a few enlargements since then
- negative perhaps a bit more on the contrasty side, however more notable differences from grade 0 to grade 3 than from grade 3 to grade 5
- yepp, lens involved.. :-)
Perhaps some misalignment of the new lamps?
If you routinely need to print on grades 4 & 5, instead of worrying about the Dichroics, I'd be more worried about my film speed and developing time. Correctly exposed and developed negatives should print on grades 2-3. I can't say if I can reach Grade 5 on my DeVere 5108 because I've never needed to. L
I agree that is the aim, and where I hope to be most of the time, but as said this was in the interest of "reference" for a new experimental VC head. And the results somewhat made me wonder. In addition I'm planning to play a bit with split grade printing, thus high grade (5) and low grade (0) easily available would be a benefit.
Yes, the filters do fade. They did in my De Vere 504. Grade 3 was the max with the old filers. New filters fixed the problem without doing anything else. Diffusion material can also yellow witch would cause lower contrast. On my enlarger, the color filters are between the heat absorbing glass and the lamps, and so they were nuked with heat. It's possible, I suppose, that old De Vere filters were less saturated than newer ones, but that seems unlikely.
Last edited by Peter De Smidt; 18-May-2017 at 17:56.
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