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  #31  
Old 11th August 2017, 06:34 AM
John King John King is offline
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The colour temp of bulbs used in colour enlargers is around 4000K so the bulb suggested by Edmund should be fine. even one with a higher temp will work, all you will have to do is introduce more yellow to balance out the blue. Apart from anything else, the current consumption of the LED is far less than a normal tungsten bulb so really it is almost a win-win situation.

The down side of the LED bulbs is thought to be the number of on-off switching largely governs the life of the bulb, this can be far less, it is all depending on largely the quality of manufacture. Whilst this figure will in all probability number in the many thousands, it may prove the need to have at least one spare to hand.
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  #32  
Old 11th August 2017, 08:48 AM
Martin Rick Martin Rick is offline
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Quote:
Originally Posted by alexmuir View Post
I have been thinking further about the idea of using the 12V LED lamps to replace the halogen types in Durst and other colour heads. Is the answer simply to replace the lamp holder with a G5.3 type? These are cheap and readily available, and come with two leads attached which could be swapped for the originals. Has anyone tried this? I anticipate the advantages would be cooler running, long life and perhaps resistance to the colour change that affects halogen lamps as they age.
Alex.


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I too had thought about it, but there is currently no LED bulb of comparable output to the MR 16 12V 100W type rhat most dichroic heads use.
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  #33  
Old 11th August 2017, 01:38 PM
Mike O'Pray Mike O'Pray is offline
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Quote:
Originally Posted by Martin Rick View Post
I too had thought about it, but there is currently no LED bulb of comparable output to the MR 16 12V 100W type rhat most dichroic heads use.
Are there ones whose output is 75W equivalent? I now have a 75W tungsten halogen in my Durst 605. I changed it from 100W a number of years ago when I found that for colour printing I needed a lesser number of seconds than my Paterson analyser would record.

It still gives me short enough exposure times for B&W.

Mike
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  #34  
Old 11th August 2017, 03:41 PM
Martin Rick Martin Rick is offline
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The last I heard was that there was now a 50W equivalent, which is a bulb widely used for shop window displays.
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  #35  
Old 1st February 2020, 11:00 PM
Nat Polton Nat Polton is offline
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https://metro.co.uk/2019/05/16/led-l...sleep-9561475/

All this talk of LED lights prompted me to post this warning article that I found whilst looking for a spare bulb for M605 today.

I wonder if looking at an LED lamp through a magnifying focus finder would pose a hazard to ones sight.



I see AG photographic have the A1/231 that I am looking for.

Cheers all.
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  #36  
Old 2nd February 2020, 12:30 PM
MikeHeller MikeHeller is offline
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We are all doomed!!

Interesting article. Thanks for posting.
Mike
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  #37  
Old 2nd February 2020, 12:56 PM
Michael Michael is offline
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My optometrist advised me a couple of years ago that, as I had very early signs of cataract that don't currently affect my eyesight, I ought to protect my eyes from UV light. So I wear prescription driving glasses whenever the sky is at all blue and, if not driving, good quality sunglasses with UV protection. I wonder whether that's what that French report was actually about (given that the journalist was probably reporting beyond their immediate competence).
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  #38  
Old 2nd February 2020, 12:59 PM
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MartyNL MartyNL is offline
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Originally Posted by MikeHeller View Post
We are all doomed!!
Mike
"It's light Jim, but not as we know it."

To boldly go where no darkroom printer has gone before...
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MartyNL
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  #39  
Old 2nd February 2020, 01:18 PM
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Bob Bob is offline
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it's a newspaper reading a press release from a scientific organisation and, as always, wholly failing to understand a word of it. Also as always, deliberately concentrating on the doom and gloom in order to increase their circulation.

High intensity visible light is known to cause damage in susceptible people. Visible light is often called "blue light" to distinguish it from ultraviolet and infrared light so it is possible the original article was using this term for all visible light.

Saying that, blue light is more prone to cause a problem as it has higher energy - the reason why UV is particularly dangerous as Michael has been warned about.

White LEDs are usually made from blue or UV LEDs that excite a phosphor coated on the LED to give the white light - hence you may want to avoid looking at white LEDs directly through a magnifier, but I don't know how much of the UV (if any) gets through the phosphor (manufacturer's datasheets will show this if it worries anyone) and by the time it has been through your enlarger to spread the beam, and given the small area of the focus finder, the final light intensity is barely enough to focus the negative so I don't see an issue there.

Just another "we are doomed I tell ye! Dooooommmed!" newspaper nonsense.

Last edited by Bob; 2nd February 2020 at 10:29 PM.
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