Shine a little light – A brief note on UV output degradation in LED floodlights

I’ve been using cheap & cheerful UV floodlights to expose my alternative process prints for a little over a year now. Since then, a few people have remarked that there’s a problem with these LED flood lights: their power output reduces as the unit operates due to the LEDs heating up. How bad is the problem, really, and what to do about it?

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Big ugly no longer big (still ugly) – RGB LED head for color printing revision

As soon as something sort of works, I generally leave it as is and use it as is. Until the shortcomings become annoying enough to actually do something about it. Which is the story of my color enlarger project in a nutshell. A story that hadn’t see much development lately – after all, it sort of worked, right? Well, the annoyance got the better of me, so I did another iteration.

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Kind of blue – A test with UV LEDs for DAS carbon transfer

So the 400nm LEDs I had been using since October or so worked really nice for dichromate carbon transfer, but I ran into trouble with DAS carbon with them. Some further testing with my bank of trusted Philips BL tubes and a little theoretical exercise suggested that at least some 365nm exposure is needed to get DAS carbon to harden reliably especially in the highlights. So I’ve been testing a bit with 365nm LED options – two in particular that seemed attractive. This is a small report on these tests.

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Fixing Sekonic L-358 and NP spot meter wrong readings

Years ago I picked up a second-hand Sekonic L-358 and have used it ever since with great pleasure. One of those things you just turn on and it works – provided you feed it a new battery once every few years or so. Recently, I got a 5 degree ‘NP Finder’ for it, which turns this incident light meter into a proper spot meter. However, today I ran into a disconcerting problem: totally wrong meter readings. What’s up with that? And can it be fixed?

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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.

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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!

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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.

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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!

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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.

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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.

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