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  #21  
Old 12th November 2020, 01:43 PM
John King John King is offline
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Quote:
Originally Posted by Alan Clark View Post
I'm a bit confused John. Back in August you were asking if we weren't all getting too fussy about the colour temperature of our enlarging bulbs. You said you were using an LED bulb rated 6500K and getting the same contrast as a normal bulb. But not now, apparently.
Anyway, I'm glad you solved the problem.

Alan
You are mixing things up or I am confusing matters! The 6500K LED bulb is ONLY used for inspection of a colour print after it has been developed, fixed and dried. 6500K is the same as noon daylight in UK. That was also for a different enlarger as well which I no longer have. Yes I did use it briefly because it was not compatible with my electronic timer. It gave a rapid pulsing light instead of a steady beam.

The 5000K bulb in the Focomat was NOT an enlarger bulb (as far as I can tell) Possibly fitted because a normal enlarger bulb was not available. Whatever reason, it was a mistake by who ever fitted it

5000K colour temperature is way above that any usual enlarger bulbs and if that had been mentioned in the previous post, I would certainly have questioned it at the time. This is a different set of circumstances completely.

Last edited by John King; 12th November 2020 at 01:50 PM.
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  #22  
Old 12th November 2020, 03:39 PM
Alan Clark Alan Clark is offline
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John, on the 30th. August in a thread titled Enlarger Lamp Colour Temperature, you said you had two 15W screw thread LED bulbs rated 6500Kelvin, and that you used one for inspection and the other in an enlarger. When enlarging with it you said "I have not noticed any difference when printing B&W with below the lens filters except the printing times are a lot shorter".
My own experience is that a cold light like 6500K won't allow the multigrade filters to work properly, so I queried what you said at the time, but didn't get much of a reply. I have no interest in winning any arguments here, and am pleased that you have a fine enlarger working properly. My only concern has been that beginners on this forum might get confused about what type of bulb works best. The answer, of course, is about 2700K.

Alan
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  #23  
Old 12th November 2020, 04:09 PM
Richard Gould Richard Gould is offline
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I agree with you Alan, I have been using the LED bulbs for 2 or 3 years now in a condenser enlarger, I decided, when starting with them, to try both cold tone and warm tone, with the cold tone I also had problems's with the MG filters, I could not get the full range of grades, so I switched to a warm tone bulb,in my case a 2700K I get the full range of grades, I use a 14.5 watt, The colder tone I tried was 4000K, Congratulations to John, you have a great enlarger there,
and glad you found your problem,
Richard
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  #24  
Old 12th November 2020, 04:23 PM
Alan Clark Alan Clark is offline
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Hi Richard, yes, 2700 K LED bulbs are great news for us. Readily available, not too expensive - and they don't give off heat. So no more popped negatives resulting in out-of-focus prints.

Alan
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  #25  
Old 13th November 2020, 08:08 AM
John King John King is offline
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Default LED Bulbs

Richard, as I have said before when I tried an LED working a while back, using simple on/off switch it worked perfectly, but when I used the electronic time the light pulsed - perhaps 6-10 times per second (I cannot count that fast).

What sort of timer do you use? I would quite like to use an LED because the Focomat only has a glassless carrier and even with the 75w tungsten bulb I have been experiencing negatives 'popping' with exposures longer than 15 seconds or so.

My timer is a Baeuerle 785 with a digital countdown with timings in 10's of seconds, seconds and fractions of a second I need that for exact timing when printing colour.
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  #26  
Old 13th November 2020, 10:05 AM
Richard Gould Richard Gould is offline
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Hi John, yes I remember you saying about the pulsing, but that is something I have never come across,
I use the RH design's analyser/pro, timer os course is part of the unit, , I can't remember what timer you have, but logically any timer should work with a LED bulb, they are just a straight replacement for the standard bulb, so can only be a problem with your timer,maybe look for another these days you can pisk one up fairly cheaply, but certainly I wouyld not go back to a standard bulb, no heat, no negative poping, so no out of focus negatives,and you don't run the risk of burning yourself touching the lamphouse after a long exposure
Richard
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  #27  
Old 13th November 2020, 01:02 PM
Mike O'Pray Mike O'Pray is offline
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Richard, looking ahead, does the bulb you have found have the kind of set-up you need if you have, as I do, the likes of a Durst dichroic head enlarger that takes bulbs with two male prongs into which the female ceramic holder fits

I have a feeling that the conclusion when LED bulbs were last mentioned was that there were not suitable lamps with prongs but that was some time ago and in the bulb market things are moving at a pace

What does 14.5 watts give you in terms of light output? Is this close to 100W in a conventional tungsten bulb?

Thanks

Mike
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  #28  
Old 13th November 2020, 02:24 PM
Richard Gould Richard Gould is offline
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I have a meopta Opemus 6, and the bulb is a standard ES, and 14.5 is around the 100 watt in a standard bulb, but it is much brighter, which means if I need a long exposure I stop the lens all the way down, my bulb came drom good old B@Q and is one of there Dial own brand bulbs, I would guess if you look around you should be able to find the right bulb for your fitting,
Richard
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  #29  
Old 13th November 2020, 02:29 PM
John King John King is offline
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Default Type of LED bulb

There are two types of LED bulb, one is dimmable and the other isn't. I haven't got a dimmer switch in the house so cannot try the one I have. If it isn't the dimmable type perhaps that is the problem
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  #30  
Old 13th November 2020, 03:37 PM
Richard Gould Richard Gould is offline
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Like you I don't have a dimmer switch, so can't check, and as the packng is long gone I can't tell you if the one I use is dimmable or not, just that mine are B@Q's own brand Dial bulb's, but you could be right, they are cheap enough now, maybe get one and try it?, if it does not work then you can still use it in the house
Richard
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