LEDs in enlarger head...

jernejk · Nov 30, 2015

So some time ago I've replaced the 12V halogen lamp with a LED lamp of similar shape in my meopta enlarger, and it worked more or less ok - I just had to "recalibrate" the color head filters by trial and error to control the contrast and that's it. I also use red LEDs as a safety lamp. I've tried, they don't fog the paper for more than reasonable time, unless they are very close to it.

Now i'm thinking - wait, the multigrade paper only reacts to blue and green, right? So why on earth don't I just use those!?
I could easily build something to mount into the head, which would have RGB LEDS, but each channel would be controlled separately.
Turn on red and you can use it instead of that red filter thingy to check the image. Turn on blue and green - each separately dimmable - and you got the best multigrade head possible.

Now i wonder, how come nothing like that has been developed in the times of darkrooms peak? LEDs were available, but I'm not sure if they were powerful enough or is that quite recent invention...

cliveh · Nov 30, 2015

Halogen lights are dead in the water and LED lights are far more efficient and economical. What you mention is the new contrast control of the future.

David Brown · Nov 30, 2015

Google is your friend ...

Try: "led enlarger light source" and among many other things, one will find:

(there was a url link here which no longer exists)

Chan Tran · Nov 30, 2015

jernejk said:
So some time ago I've replaced the 12V halogen lamp with a LED lamp of similar shape in my meopta enlarger, and it worked more or less ok - I just had to "recalibrate" the color head filters by trial and error to control the contrast and that's it. I also use red LEDs as a safety lamp. I've tried, they don't fog the paper for more than reasonable time, unless they are very close to it.

Now i'm thinking - wait, the multigrade paper only reacts to blue and green, right? So why on earth don't I just use those!?
I could easily build something to mount into the head, which would have RGB LEDS, but each channel would be controlled separately.
Turn on red and you can use it instead of that red filter thingy to check the image. Turn on blue and green - each separately dimmable - and you got the best multigrade head possible.

Now i wonder, how come nothing like that has been developed in the times of darkrooms peak? LEDs were available, but I'm not sure if they were powerful enough or is that quite recent invention...

Yes I think you can do it and also instead of varying intensity you could do it by time that is expose for the blue and green light with different exposure time. LED dimmer may be difficult to make especially you need to dim them linearly.

Steve Smith · Nov 30, 2015

I modified my DeVere 54 with the PCB from an RGB LED stage light. If you do a search you should be able to find mention of it in two or three threads.

Steve.

mnemosyne · Dec 1, 2015

For all that are too lazy or clumsy for this kind of DIY job, there is a commercial product that uses this concept. For some time now, German company Heiland has been selling a LED powered cold light source for various enlargers from 6x9 cm up to 12x16 inch.
Link to product page is here.

payral · Dec 1, 2015

mnemosyne said:
For all that are too lazy or clumsy for this kind of DIY job, there is a commercial product that uses this concept. For some time now, German company Heiland has been selling a LED powered cold light source for various enlargers from 6x9 cm up to 12x16 inch.
Link to product page is here.

Heiland did one for my Zone VI Type II enlarger (5x7" size) and it works like a charm. Much more powerful than Zone VI original head and better contrast range.

Luis-F-S · Dec 1, 2015

jernejk said:
Now i wonder, how come nothing like that has been developed in the times of darkrooms peak? LEDs were available, but I'm not sure if they were powerful enough or is that quite recent invention...

Cause if it ain't broke, don't fix it. L

Luis-F-S · Dec 1, 2015

cliveh said:
Halogen lights are dead in the water and LED lights are far more efficient and economical. What you mention is the new contrast control of the future.

I don't disagree, but since I can re-lamp my DeVere 5108 for under $20 with Halogen lights, and the Heiland LED head for my enlarger is around 200 times that, I think I'll keep my halogen. FWIW, I have well over 100 halogen lamps store for my enlargers. Enough for several lifetimes. L

DREW WILEY · Dec 1, 2015

LED's aren't very bright compared to halogens, are a relatively new thing (so specific replacements units might or might not be available later
on), and the RGB spectral accuracy is still far from suitable for color printing, at least. But experimenting with LED's might be an appropriate
option to a cold light for black and white work.

RobC · Dec 1, 2015

why? the enlarger is designed to work with white light and you have filters for it. Why complicate things by using green and blue light which are additive and not subtractive. The paper is designed primarily for for subtractive filtration. i.e. ilford filters are designed to be subtractive. Using blue and green light won't give you anything extra except possibly a little more contrast but you shouldn't need that unless your negs are way off. How often do you print at G5 and need more?

What light will you compose and focus with, white? So you need white light anyway. So all you would be doing is complicating things.

DREW WILEY · Dec 1, 2015

Depends on what the allegedly white light is actually composed of. LED's complicate that. The V54 cold light I use gives off blue-green light, so is ideal for split printing. Or any conventional colorhead works superbly; but these have full-spectrum basic halogen bulbs. But no, paper does not see subtractive colors like Magenta or Yellow. It actually sees the complement filtered out: either blue or green. So I personally just use hard blue (47) or hard green (58) glass filters below the lens to split print. But this is relative to a very powerful cold light. Deep separation filters need this due to their density. Otherwise, subtractive M and Y in gradations works better, from a purely practical standpoint. My actual additive colorheads are the most elegant solution. I might use all the above in a single session, because most of the most of the real work involves cleaning the negs and carrier glass in the first place. So I load up several different enlargers in
advance, maybe a few days before. But I can go back and forth between all of them and get analogous results. Just takes some practice
and familiarity with your specific gear and chosen papers.

Steve Smith · Dec 2, 2015

DREW WILEY said:
LED's aren't very bright compared to halogens

Having taken apart and powered up some LED car headlight units... I disagree!

All of our street lighting is LED. There is no reason why an enlarger light source cannot be as bright as halogen. Perhaps, not replacing a single bulb with a bulb like device, but it is easily possible now.

Steve.

mnemosyne · Dec 2, 2015

Steve Smith said:
Having taken apart and powered up some LED car headlight units... I disagree!

All of our street lighting is LED. There is no reason why an enlarger light source cannot be as bright as halogen. Perhaps, not replacing a single bulb with a bulb like device, but it is easily possible now.

Steve.

Two positive side effects are that it is very easy to get very even illumination into the corners and that the cooling requirements are much lower. According to Heiland the power draw is a quarter of what you would normally see from a halogen light source for the same format. As a consequence, even the 8x10 Heiland unit does not require active cooling (fans). No noise, less dust and less heat stress on your negatives sounds like a good thing to me.

For me personally the investment in such a (commercial) LED light source is just not justified, as the biggest negative size I regularly enlarge is 6x9 cm. Passive cooling is possible here with a 100W halogen light source. So, heat is not such a big problem and replacement bulbs are still cheap ...

DREW WILEY · Dec 2, 2015

Heat is indeed the Achilles heel of halogen. And LED's might seem bright, but how much of that light is specifically usable is a different subject
in the world of printing slow papers. But with Cibachrome gone, and only a few people actually enlarging Azo-esque "contact" papers, that really leaves only big mural work as an issue. I once had a big Durst color mural enlarger where just the cooling fan used mere electricity
per month than my whole house. One exposure would warm the whole room up. No need for a heater. The cost of maintenance to the filters and reflectors was obscene. Glad them days be gone. Of course, this thread seems mainly concerned with VC papers, so LED is a more realistic option for that kind of application. On the Isle of Wight, paper is generally exposed at night with aurora borealis light thru
a window. Dodging and burning is tricky.

Luis-F-S · Dec 3, 2015

mnemosyne said:
Two positive side effects are that it is very easy to get very even illumination into the corners and that the cooling requirements are much lower. According to Heiland the power draw is a quarter of what you would normally see from a halogen light source for the same format. As a consequence, even the 8x10 Heiland unit does not require active cooling (fans). No noise, less dust and less heat stress on your negatives sounds like a good thing to me..

And you get all this for 4 big bill$. I'll keep my Halogen!

Neal · Dec 4, 2015

Let's just admit it. The number one reason to build an LED head is that it would be fun to do. Justification is unnecessary.

jernejk, if you decide to build one, enjoy and report back. I look forward to the results.

Good luck,

Neal Wydra

gphoto120 · Dec 4, 2015

FYI : This LED system is for Omega enlargers and has gotten very positive reviews from some folks on Large Format Forum.

http://www.modernenlargerlamps.com/Modern_Enlarger_Lamps/Welcome.html

M Carter · Dec 4, 2015

Do LEDs have any significant startup issues like Fluorescents, HIDs, etc? Or are they instant-on enough for printing use?

swdick · Apr 14, 2016

I rebuild a Durst Multigraph on the basis of green, blue and red Lumi LEDs and a Arduino to control them.
I can now set filter grades as fine as I wish.
Be sure to use the royal blue to get to grade 5.

Have fun.

Nodda Duma · Apr 14, 2016

jernejk said:
Now i wonder, how come nothing like that has been developed in the times of darkrooms peak? LEDs were available, but I'm not sure if they were powerful enough or is that quite recent invention...

Timing and cost: The blue LED was invented in 1993 by Shuji Nakamura, and didn't trickle into the market for OEM until a couple years later. If I remember correctly the lifespan of blue LED was relatively limited and the cost was still high for a few years. To develop the drive electronics to control the LED's would have been significant NRE for a device more expensive than the tungsten/filter lighting systems of the time. Even then it was apparent that digital imaging was coming and coupled with the uncompetitive cost meant there was no real need to do develop an LED-based enlarger.

RalphLambrecht · Apr 14, 2016

jernejk said:
So some time ago I've replaced the 12V halogen lamp with a LED lamp of similar shape in my meopta enlarger, and it worked more or less ok - I just had to "recalibrate" the color head filters by trial and error to control the contrast and that's it. I also use red LEDs as a safety lamp. I've tried, they don't fog the paper for more than reasonable time, unless they are very close to it.

Now i'm thinking - wait, the multigrade paper only reacts to blue and green, right? So why on earth don't I just use those!?
I could easily build something to mount into the head, which would have RGB LEDS, but each channel would be controlled separately.
Turn on red and you can use it instead of that red filter thingy to check the image. Turn on blue and green - each separately dimmable - and you got the best multigrade head possible.

Now i wonder, how come nothing like that has been developed in the times of darkrooms peak? LEDs were available, but I'm not sure if they were powerful enough or is that quite recent invention...

Heiland Electronics in Germany build such a head for some enlargers already.

paul ron · Apr 14, 2016

Also high power LEDS are recent as well.

LEDs in enlarger head...

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