4x5 enlarger conversion, DIY LED head

[konakoa]

konakoa submitted a new resource:

(there was a url link here which no longer exists) - 4x5 enlarger conversion, DIY LED head

This article was originally part of a website I maintained. The website is no more, so I wanted to update some information and place the contents of the old page here for anyone who may still find it interesting. This project was one I thought was really interesting and fun. In it I took an old medium format Beseler 23C enlarger and converted it to work with large format 4x5 film. I also made a homemade light source for it using LED lighting.

What I thought was incredibly useful about...

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

 

[Steve Smith]

I have already discussed my enlarger head in a couple of other threads. I plan to try something else soon.

The company I work for makes the flat, flexible LED light panels in this company's website: http://designledproducts.com/

My intention is to try something like that.


Steve.

 

[NedL]

Thanks for posting this here on APUG! I think it is great to put it here where it can be useful and will be preserved for the future.

I have a copy of your original website saved in case of future need. For me, just knowing that it is possible to make a DIY LED head that would work well with VC paper was important. I have an old Zone VI cold head light, and was worried about whether I should buy 1 or more V54 lamps for it while it is still possible ( they are quite expensive ). Reading your webpage helped me decide that I can use what I have for now and have other options if/when the lamp finally fails. So I would just say that I think the careful work you did characterizing the spectrum of the LEDs was also important, and not just the 4x5 conversion!

Thanks!

 

[hgernhardt]

Silly question—

Looking at the finished setup, I have to wonder why it won't work for 35mm any longer. Is there a mechanical limit to bellows collapse that prevents it?

 

[konakoa]

Henry, that's it exactly. The two bellows sets combined are so thick that they won't compress enough to get a 50mm lens to work correctly. A recessed lensboard might work, but it'd need to go up into the enlarger about two inches. Edit: You could also leave the bellows exactly as they are-don't combine the two sets. This will just work, but only with a 135mm lens and you will also have to flip the mount for the focusing stage around to drop the lens down just a bit. A 150mm lens will be too long.

One other issue is the brightness of the lamphouse. When you go from the big surface area of 4x5 down to 35mm, the physical size of 35mm film and the smaller opening in the negative carrier drastically reduces the amount of light available--instead of having all of the light from the head to illuminate the film you're now only using a small amount that goes through a narrow opening in the middle. If you have a 4x5 color dichroic or cold light you may have experienced this when swapping out 4x5 to medium format to 35mm negative carriers. Color heads sometimes have interchangeable 35mm mixing chambers/boxes that really help with this.

 

[hgernhardt]

Henry, that's it exactly.

Thanks, I thought that might be the case.

One other issue is the brightness of the lamphouse. When you go from the big surface area of 4x5 down to 35mm, the physical size of 35mm film and the smaller opening in the negative carrier drastically reduces the amount of light available

Makes sense. Thanks for the information! I've been looking for this article for ages now.

 

[werra]

The article is inspirational indeed. I have been toying with the idea to construct a 5x7 light source from one of those inventions, available for less than $10:



It disassembles easily and has all the necessary components for running directly from 220V. The spectrum is yet to find out about.

 

[Mainecoonmaniac]

I saw this at Ikea. Is it useful for and led conversion?

 

[Mainecoonmaniac]

I saw this at Ikea. Is it useful for and led conversion?

http://m.ikea.com/us/en/catalog/products/art/20119418/

 

[Randy Moe]

konakoa, We have communicated a few times. Thanks for posting your research and results. Saves many of us fruitless experimentation. I plan to soon make a 10x10 version using Chinese 12"x12" 1000 Led video lights I already own. I think one will be plenty, but 2 could be mounted in a mixing box. I first bought the 3400K to 5600K variable 7"x10" LED model. I was thinking I could vary frequency but that may not be necessary, as your research seems to show, Initially I will just use one white spectrum. The 12x12' are all 5600K. I am wondering if the higher frequency 5600K LED's will adapt to the MG filters as easily as lower frequency light. I believe most old enlarger bulbs were 3200K.

The US. Plastics source is great, I had already scoped them out. First I will try diffusers that came with my lights. I use McMaster Carr and Grainger for other raw materials.

One thing you did not disclose is printing times. Do you have any plans to discuss them?

 

[konakoa]

Werra, glad I could be inspiring! Randy, I remember our emails. I've experimented with white LEDs from 7000K (cool blueish light) to 2900K (yellowish). I had some troubles with the 7000K--which I now think was a flaw in my testing procedure--but regardless I wouldn't suggest 7000K white LEDs because the greater bias of blue color raises the unfiltered values of variable contrast paper. Even with filters 7000K was tricky to print with, so again I wouldn't suggest that color. 5000K to 2900K worked just fine in my experiments and in my working LED head. Printing times with a normally exposed 4x5 neg in my LED head are roughly from 3 to 15 seconds with the lens at f/11. The longer times are with filters used.

Mainecoon (I like that name) I'm sending you a PM.

 

[Randy Moe]

konakoa, good advice, I will stay away from 7000K enlarging lights, but I do like 8000K tube fluorescents for interior lighting my cave.

I just pulled out a book I should have read a long time ago. 'The Variable Contrast Printing Manual' by Steve Anchell, 1996. it was given to me, but at that time, I was too busy switching to digital to pay any attention. Now that I realize my folly, it makes a very good read. His introduction makes a good point,

'...the testing for this book was conducted largely in the old way, by using the materials with a variety of developers and toners and by visual inspection. When applicable, I judged the results visually, not electronically. I call this "the cookbook: method.' He also means enlargers.

Steve goes on to explore VC paper, enlarger light sources and filtration. LED's where not available then. He makes the point, that there is no such thing as a correct process or print. It is all subjective.

I plan to keep this book close, as I return to the wet side, along with his other great book, 'The Darkroom Cookbook.'

Your print times are much shorter than I imagined. Good news!












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[jp498]

I've always liked Omega negative carriers and beseler enlargers desite the negative carriers. Have Fun!

Looks like you nailed it well replicating the cold light head output with LEDs. I may copy your LED head for use with my beseler 4x5 enlarger; it's color head works fine but needs an obnoxious noisy blower and isn't super bright.

 

[konakoa]

JP, please use any part of this project that you'd like. If you do build one, all I ask is you post pictures of your finished enlarger. For all the years I ran my website I never had anyone send or post pictures of another LED enlarger head. I think it would be fun to see how someone else goes after the project. I'd also be glad to help with ideas, test results or methods--just send me a note or post here.

 

[jp498]

I was familiar with your website, but hadn't seen the step wedge results comparison till today.

 

[dubtom]

Inspiring idea. I've just taken up LF a while back, my two enlargers I need for 35 and MF so was considering using a spare Calumet cc401. Removing the gg for the light source and using a film holder for the neg could work,perhaps. It has a max of 22'' of travel on the bellows, I used a lamp for a crude test with my 305mm LF lens to see how much projecting at maximum I would get, very little it turned out, I had to retract the bellows almost fully to get enough coverage for even a 10x12. I'm assuming by using a smaller lens,perhaps a 150mm proper enlarging lens I would achieve more coverage? Obviously I haven't thought of a way of using the camera vertically yet, but that shouldn't be too difficult.

 

[Polder]

Hi! Being from the pre multigrade era and after years of Video picking up pace again. I am busy learning to make my own printing paper and glass plate emulsions ( the Lightfarm Tutorials ). I have an old Teufel enlarger for 13x18 cm and a Kienzle up to 9x12 cm. I wonder if this Led lamphead could be used for enlarging on AZO paper. A lot has been said about this but I sure will give it a try. It will take a couple of months and I´ll report back on failures and hopefully successes. Thanks a lot. Henk

 

[stormpetrel]

You might find useful the compilation of photographic paper sensitivity spectrum here on this (there was a url link here which no longer exists)

 

[konakoa]

Polder, what I know of AZO is that it is very slow to expose--it is primarily used as 'contact' printing paper as it is mostly ultraviolet light sensitive. This makes it difficult to use for enlargements. It's not nearly as quick to expose as enlarging paper from Ilford or Foma.

Very nice work Stormpetrel! Such amazing sophistication in your designs. When do you expect to have that LED head finished and tested?

 

[Polder]

Hi all, Thanks for replying. I know that the paper I am trying to make myself is as slow as can be. But I have high hopes of these new LED's. Anyway the ceiling in my darkroom is a bit on the low side, so I need something far flatter than the huge dome that sits on the enlarger now. On the other and Denise Ross of the Lightfarm might come up with a new recipe that makes enlarging an option. Anyway the ceiling you know. Thanks again. Henk.

 

[stormpetrel]

Thank you Konakoa. I will try to finish it this weekend but my free time is very scarce...

 

[hgernhardt]

Polder—

If AZO paper is primarily UV sensitive, perhaps you could investigate the peak wavelength of its sensitivity along with available UV LEDs.

 

[Polder]

Hi Henry, Thanks, I´ll just do that. If any Progress is made, I´ll report back. Henk

 

[Resurgance]

Hi Konakoa,

Nice work on the LED head, very well put together and the finished product looks superb with printing results to match by the sounds of it.

I am new to APUG, but have been looking at this very thread for months now with interest - I just recently completed an LED head for my LPL7700, in an attempt to create a brighter light source with a VCCE head, but it was a complete flop. I wanted to utilize the existing mixing box and filter set in the enlarger head, which is designed for a halogen.The LED I used was top notch, a Philips HBM module, with the matching 1-10V controlled dimmer constant current driver, 6000 lumens, and 3000K colour. However what I did not count on was how concentrated the light source from a 100W dichroic halogen lamp is, and instead was focused on the lumen output of the module, without thinking about it fully. The LED module is partially diffused from the start, or at least is not focused by a parabolic reflector like the halogen, I see now why it did not work. The light output was poor, and most was lost before it got to the mixing box, not being directed and all.

Anyway, your design has re-inspired me to try a new project, as I have recently picked up a Devere 504 enlarger with a Dichroic colour head, and want to try and tackle a project based on the ilford multigrade head, and using a green and blue LED array in a configuration like yours and trying to emulate the Heiland LED VC source. I was going to use dimmers to control the intensity of the green and blue LEDS individually and try to come up with some 'grades' based on the step wedge I guess.

I just noticed you had a link to Stormpetrels VC head, do you know how that went in the end?

Thanks for sharing your work!

 

[konakoa]

Resurgance, thanks for the kind words and I'm happy my work could be of use to you. I would caution that blue LEDs don't play too nicely (at least the ones I used) with variable contrast paper. Please see the 10th paragraph section "To test how darkroom paper..." in my article above on LED colors and my spectrograph pictures. The only reasonable solution would to be to filter out the green crossover within the blue LEDs--probably by gluing tiny bits of filter material with clear optical cement over every single blue LED. A silly notion but it may work for the determined.

I never did hear back from Stormpetrel. I assume it all worked out and he just got busy printing. Not a bad thing!