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.
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%).
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.
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.
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