electronics – Page 2 – Koraks tinkers

Different kind of print – Making PCB’s at home

Sometimes (frequently…) I get sidetracked from photography because I need some kind of equipment or trinket. In such a case I could just go online and order whatever it is that I believe I need. But most of the time I end up DIY-ing something, especially if it’s an electrical device. And that involves making PCB’s. Out of necessity, I have become reasonably good at making these at home. Let me share my current way of working, as it involves a few tricks that make this a little easier.

Potato, potato – Making an old Sigma lens work on every Canon EOS body

Right, the “potato, potato” thing probably doesn’t work that well in writing, but you get the point. Or at least, you soon will. I got my hands on an old Sigma ‘Super Wide’ 24/2.8 a couple of weeks ago. I came across it and just couldn’t resist; a wide-angle prime is a convenient thing to have, after all. Upon receiving it, I immediately tried it out and…it didn’t work properly. Drat. Well, it did on my old Canon EOS 50e, but it didn’t work on an EOS 7D or an EOS 30. Turns out it’s a well known-compatibility issue. Turns out also that, guess what? It can be fixed!

Roll another one…modifying the Durst RCP20 for RA4 processing

Sometimes I’m just incredibly lucky. Tabletop RA4 roller transport processors are unobtanium these days and if you find one, it is likely to be insanely expensive. I happened across a Durst RCP20 (which in fact is a Thermaphot machine, but Durst sold them under their own brand). These machines have a few drawbacks though, which boil down to them being darn old pieces of equipment. First and foremost, to be able to use mine, I had to convert it to run at the right speed for the current RA4 color paper process. Here’s how I did this.

Beam me down, Scotty: a new ultra-simple UV light source

It’s been a while since I wrote a somewhat acrid blog about the 300W UV floodlight unit I bought from AliExpress. The tone was acrid, because 300W in reality turns out to be about 75W. The conclusion was somewhat counter-intuitive, as I also mentioned that I found the unit so abysmal, I planned to buy some more of them. The reason is simple: while the unit doesn’t live up to its specifications, it still gives a lot of bang for your buck, and most importantly, it’s super easy to implement. Well, you be the judge of that!

The Big Ugly, part 4: (im)perfect present

Here we are, and this is Now. So far, I have written about the two generations of problematic and/or quasi-successful color enlarger light sources I’ve made and the lessons I’ve learned along the way. But all that is in the past. This blog is about the current, 3rd generation of the LED color light source for my (t)rusty Durst 138. It incorporates most of the lessons I learned along the way – and brought me some new ones, no doubt.

The Big Ugly, part 3: proper SMD LEDs, but no cigar (?)

In the previous part of this series, I told about the lessons I learned by trying to use a single RGB COB LED as a light source for both RA4 and B&W enlarging. I took those lessons and gave it another go, this time using a fundamentally different approach. As the title suggests, no cigar yet – although this isn’t really accurate. The second generation device I built was actually used for a year or two before I was sufficiently annoyed by its shortcomings to replace it. So the second generation actually did work – albeit with some caveats.

The Big Ugly, part 2: the RGB COB LED approach to color enlarging

Previously, I explained why I thought I needed a color light source and in general terms what it should be capable of. I also highlighted that it’s not so much a project with a clearly defined end (or at least, that hasn’t materialized yet), but more of a journey that continues into the present, and probably future as well. In this part, I’ll go through the phases this project has gone through. That is to say, there are really three distinct generations of the device I’ve built, and each has taught me different lessons. Before going into some details of the current (and 3rd) rendition, I’ll try to go through each generation and explain what it was/is and what its main caveats were (especially generations 1 & 2). Let’s start with the first generation I built.

The Big Ugly, or building a LED color printing light source. Part 1: the beginnings

Previously, I bashed compound/integrated RGB LEDs such as RGB COB LEDs for the application of a color enlarger for RA4 prints. That was basically a lesson learned the hard way when building a LED-based color enlarger light source. In this series, because one post is probably not going to be enough, I’ll highlight some aspects of the system I’ve built. Or I should say: I’ve built so far, because it’s really just a prototype that will likely never be really finished. Hence the title, The Big Ugly. Because there’s one thing it isn’t, and that’s beautiful. But hey, it works! Sort of. Most of the time. Within reasonable limits. If I’m careful.

Why RGB LEDs suck for a color RA4 enlarger

Not many people are crazy enough to build a light source for a color enlarger. From time to time, someone picks up the challenge and posts about it online. Most of the time, the concept revolves around some form of RGB LEDs, whether that be led strips, Chip-On-Board (COB) LEDs or even addressable LED ‘beads’ such as the popular WS2812. All of these are in my opinion doomed to fail miserably to produce quality RA4 prints. Let me explain why.

Some light to the darkroom

What’s the essence of a darkroom? That’s right – light! Seriously though, I think good light makes all the difference in darkroom work. First and foremost, it’s just pleasant to have ample and good-quality light to work with. But it’s also essential for judging print quality and properties such as hue/color balance, toning etc. In this post, I’m showcasing my current darkroom lighting setup and I will also discuss some lessons learned and loose ends/issues.