Durst Taucoli Cold Light Usage
What a great resource for analog photography! (this is my first post)
After a bit of searching past threads, I would like some advice from users of cold light heads generally, and particularly of the Durst Taucoli cold light (used on my Laborator 1000 4x5).
I realise that the head uses a flourescent tube and that it takes some five minutes (or more?) before the light output stabilises (checked this with an enlarging meter). I was originally getting inconsistent test strips depending (I think) on how long the enlarger is actually on.
My question is: Do you normally leave the enlarger head switched on during a darkroom session and cover the lens with a card until needing to expose paper and just use the timer unconnected to enlarger?
Regards Tony Russell
That's one option.
I found that when I switched from an old Graflarger back to a new Aristo D2 High output head, which has a heater to keep the tube at a more stable termperature, I got much more reliable results.
Another option is to use a compensating timer with a probe that measures light output and adjusts the time accordingly, like the Metrolux timer available from Calumet. If I find myself using the Graflarger again, I'm going to get one of these.
I'm wondering if you're using your cold light (with the heater) and you set a base exposure of (say) eight seconds, followed by a couple of three second 'burns', how will the head have time to warm up and stabilise? (I know these are short exposure times, but they give reliable results using other (condenser, diffuser) heads I have.
And then, ten minutes later you want to test another area of the image (same base exposure). The head would have cooled down by then....I just thought - maybe the heater is left on in the head during standby?? ..could be wrong.
And would this be a typical exposure regime in your darkroom, giving consistent results?
I can see that the compensating timer would work well here, but I'm not ready to spend more money on such a timer yet.
It seems pretty good under the conditions you've described.
The heater and the light are two separate circuits. The light is plugged into the timer, and the heater is plugged into the wall, so the heater stays on between exposures.
I'm sure it would be even better with a compensating timer, but this definitely works better than the old-style cold light head, which made it difficult to do a consistent run of prints from the same neg.
You've confirmed what I thought about the way the (better) cold light heads operate. I may try rigging some sort of heater/temp control within the head housing and see how it works out.
Thanks again for your help
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Aristo offers upgrades of some older heads, many of which they actually manufactured for other brands. Maybe they can give you a new V54 tube (better with VC papers than the old tube, and just as good with graded papers) and add the temperature control device. I think the website is www.aristogrid.com.