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Thread: DIY 4x5 Enlarger with LED light source

  1. #1

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    DIY 4x5 Enlarger with LED light source

    I wanted to present my project of a DIY 4x5 enlarger. Maybe one or the other has an interest or an opinion. I (like so many others) stopped taking analog photos some time ago and developed them myself, firmly convinced that these times will never come back. When my daughter (18) showed me one in her opinion world first cameras without SD card and said that if you send “somewhere” you will even get the pictures "printed" back on paper, it was time to take up this hobby again. She now photographs with my old 35mm Canon.
    I, on the other hand, wanted more and tied to my old dream of a large format camera. A student in the late 80’s I couldn’t afford it. The choice fell after a research on a WISTA 45N.
    While I was still waiting for my eBay purchases I asked myself how I would put the 4x5 stuff on paper.
    I had already built a 6x9 enlarger out of wood, cardboard and aluminum profiles as a student 30 years ago.
    With better knowledge and even more vision I started to work. The linear guides from the 3D-industry that you can get cheap nowadays were a good help. The bellows was (as I expected) the biggest challenge.
    Many may wonder why I chose such a shaky construction for the column. Quite simple: I don't have my own darkroom and have to be able to set it up and take it down quickly. Also, the place I use as a temporary darkroom is under a pitched roof and I can't put a bigger enlarger on the tabletop.
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    But the aluminum tube is quite robust and you can fix it to the base plate with almost no play.
    The head of the Enlarger had a LED ceiling light at the beginning. You could set it to 3000, 4000 and 6000k, but I didn't get good results. The contrast was quite weak despite the MG filter I put under the lens. In the RA-4 process, the densities of the filters used were also enormously high (well over 150). So I asked myself what other light source I should use.
    My research showed a confusing picture. Those who used LEDs could achieve good results, but used only green and blue LEDs. These posts were also some years old. But I also wanted to be able to make color prints for RA-4.
    First I concentrated on black and white and the problem of contrast control. So I understood it was important that the blue LED should not shine above 470nm. Each nm below 470 brought me closer to a useful contrast control. The green LED didn't seem to be the problem.
    I looked around and my (relatively good) Arduino experience brought me to the WS2318b LED. They shine in blue around 467nm and are digitally controllable. Since I had already built a digital timer with Arduino for my Durst M606, I used the 256 (16x16) LED Matrix (clone) from Adafruit (with 256 WS2318b -> https://www.adafruit.com/product/2735 ... Or aliexpress) which has about 50 Watt (if all RGB colors are 100%).
    Click image for larger version. 

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    I build and programmed a control unit with a numeric keyboard, timer and adjustable YMC or RGB values as well as an option for the MG VC contrast vvalues. There is also a cable remote control for the start of the timer (I will switch to an IR remote control). The contrast values you can set can go linear from full green to full blue.
    Click image for larger version. 

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    A first test of my arbitrary contrast values 1 to 5 gave good results. I don't think I can achieve a contrast of 5, but that doesn't bother me much. This is also where my adventure ends at the moment. I will test the RA-4 suitability in the next days. I am open for questions, criticism (be open but gracious) and suggestions.

  2. #2
    Tin Can's Avatar
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    Re: DIY 4x5 Enlarger with LED light source

    First I read it, then i looked up "Tuggen"

    Good job and valuable addition to the many DIY threads already here

    Looks like you do a lot of DIY
    sin eater

  3. #3

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    Jun 2019
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    Western Massachusetts, USA
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    Re: DIY 4x5 Enlarger with LED light source

    Interesting read! I'm in need of a light source for my 8x10 enlarger, and am planning to build an LED one. I was thinking of going with cree LED stars wired to potentiometers for dimming control, but I'm intrigued by your digital control method and RGB LEDs. Why is it you don't think you can achieve contrast 5? Looking at the wavelengths, it seems the cree stars will have no issue hitting contrast level 5, but with a digital controller like you used, I image replicating results would be much easier than with potentiometers. I do use split filter printing most of the time though, so having high contrast is important... aarghh! I will need to do even more research now I suppose, to determine which method I will use.

    anyway, I eagerly await your report on how it goes with color printing, good luck!

  4. #4

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    Re: DIY 4x5 Enlarger with LED light source

    Cree LED stars go down till 450nm. That hits the highest contrast for sure. With some FET transistors you can control it digitally too with an arduino.
    I'm trying to find out how cose to contrast 5 I can go, but I think it's enough for an usable split filter printing. These Neopixel Matrix LED are quiet confortable to use and don't need hardware such additional FET-transistors or similar beside an Arduino and a power source.
    in btw: I had a first RA-4 test Yesterday and it seems to work well. I will post some results later on.

  5. #5

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    Re: DIY 4x5 Enlarger with LED light source

    Very cool - congratulations. I'm looking forward to seeing more. Nice to see more and more people coming back to film - especially when they can bring DIY solutions like this.

    Regards
    Dave

  6. #6
    jp's Avatar
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    Re: DIY 4x5 Enlarger with LED light source

    Beautiful; thanks for the details!

  7. #7

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    Re: DIY 4x5 Enlarger with LED light source

    There you go. After some tinkering with my color head control I got very good results with RA-4. Unfortunately, I only exposed a few 4x5 color negatives, so I don't have a large selection of reference images. Also the few I have shot under bad or unusual light conditions. But I know the conditions very well when I took them. I am very satisfied with color and brilliance. It doesn't make much sense to show them here, but I do it anyway even if it's only a mobile phone picture of the actual picture, and therefore of bad quality:
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    The RGB values of the LED are controlled with an 8-bit value between 0 and 255. Only the upper range (resp. lower range because we want to generate YMC values) from 190 to 255 makes sense. This would correspond to the density values between 0 and 130 for a normal color magnifier (quite empirically). I think so.
    But I don't see any negative aspects when using LEDs. At least not compared to my DURST enlargers with color head.
    This LED light source is absolutely suitable for color photos.
    I can enter the values exactly and even save them and use them again if necessary. This makes working more comfortable.

  8. #8

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    Re: DIY 4x5 Enlarger with LED light source

    I had some PM with request for the code and bill of materials. I made a hook-up drawing too, but I'm not able to upload it in a decent resolution. Please PM me if you need it in readable resolution and I send it to you. This project still needs some basic Arduino skills to build. Nothing terrible but at least one should know how to install a library and so.
    This is a version with an integrated timer. For a version that uses an external timer the code and a bit of the hardware should be changed. even this layot can be misused for use with anexternal timer if the toggle switch for the permanent light on is let on.
    This version still not uses the EEPROM store, but I will implement it soon. The bill of material is in the comment section of the code.
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    colorhead_code.txt

  9. #9

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    Minneapolis, MN
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    Re: DIY 4x5 Enlarger with LED light source

    Thank you very much for this info and the work you put into it.
    Reid

    http://www.flickr.com/photos/rjbuzzclick/

  10. #10
    jp's Avatar
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    Re: DIY 4x5 Enlarger with LED light source

    Very nice! Looks like a great project for the winter! Looking forward to replacing the dichro head and vacuum cleaner noisy fan on my CB7 enlarger.

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