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> Duka 50 Controls |
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#11
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If you look at one you can see why they used to cost so much. They are literally a bulb within a bulb with the outer covering having a dichroic coating on the inside of the glass envelope. They would have no other use than darkroom printing so a quite limited market Have you ever tried testing your current set-up to see when/if it fogs the paper. Get a piece of paper and expose it to the darkroom with only the safelight on for 1 minute then up to 5-6 steps with a one minute step longer than the one before. Examine the results in good daylight and the step before fogging becomes visible is your limit of non printing/developing time. I can describe my setup from cutting the roll and storing cut sheets if you wish but that is likely to be a rather long post. |
#12
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I am using my €3 red LED bulb very happily for Multigrade. I don't know where to get them in UK and the bazaar from which I bought mine has all the colours except red (I think I bought them all).
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#13
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Sorry for the confusion, John. Yes, I have a Duka 50 from Osram, but I ever thaught using it for printing colurs one day. Now I wanted to know about the reason for working perfect as b&w safelight. I have seen describing you the bulb being covered by a dichroitic extra bulb which seems to allow the passage of green/yellow and or blue light ? Lately I am lucky to use my 5Euro LED bulb, too. Cutting rolls of course is worth another thread - for example and concerning its unruly, curling up behavior I first start with flipping over my Foma rolls :-) |
#14
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I've only just realised that there were three posts prior to me posting this one, but I think that it's still relevant.
So, Reginald, the bulbs mentioned are said to be rather expensive... A much cheaper option is a LED bulb that I have found to work for a good length of time and is a LOT cheaper. After initial tests, I bought some more and use a two bulb holder to use two of them at a time to give more illumination and they work fine. I'm now wondering if it's possible to use three or more, although the illumination I am getting is more than workable. Check out this thread, but mainly from post #27: http://www.film-and-darkroom-user.or...273#post145273 Terry S Last edited by Terry S; 30th May 2022 at 11:48 AM. |
#15
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So, I did a test of a number of the cheaper red LED bulbs available and eventually found one that worked. This is the thread that I talk about it. Main bit of text from post #27: http://www.film-and-darkroom-user.or...273#post145273 And this is bulb in question: https://www.ebay.co.uk/itm/353939556530 Terry S |
#16
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Thanks Terry,
I'm not in need of such an expensive Sodium bulb becaus there is fitted one in my Duka 50. The last years I made good experience with an LED as a safelight which is called "" Osram Deko Spot ""here in germany. This is a white bulb with some kind of red filter foliage glued on its surface. But it seems to be gone, too. |
#17
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The rolls of paper do curl badly when you get to the centre core can be a bit of a struggle to keep flat. What I do is cover the work surface with a large piece of clean mounting card and as each piece is cut, I have it face down on the surface and with a 300mm ruler start at one end and lift the paper and at the same time move the ruler towards the opposite end and that way you can remove most of the paper curl without damaging the sensitive surface. At most with a 16" sheet that should only take 5 seconds and as the sensitive surface is away from the safelight there will not be any problem with fogging.. I have never considered using any LED in the darkroom because of the unknown wavelength of the emitted light. It may look red to us, but the sensitivity of photographic materials is a different matter. I will stick with my Duka and as a fall back, a Kodak wall mounted unit and red filter with a 15w tungsten bulb. If it works for anyone else - fine but I will not be using them. Last edited by John King; 30th May 2022 at 03:54 PM. |
#18
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Contrary to other paper fabricians Foma didn't turn the paper after its production, so its behaviour out of the box is nearly like a metal spring.
Turning my paper of 108cm width to 180 degreees onto another roller core gives it the required relaxation during the next days. Specifications like wavelenghts or sensitivity of our paper must not be unknown thisadays. One could buy LEDs with very specific wavelength range if interested, but I also understand the use of good old stuff like perfect bulbs or my 100 years old Reisekameras:-) |
#19
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I now have the red filter but I think it is pretty useless, can't see a thing with it in place. SO WHAT ! I hear everyone say.
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#20
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