Koraks tinkers

Solid as a rock – Fixing an old AC stabilizer

Sometimes, a piece if equipment finds its way to me for repairs. This time, it was an old Devere voltage stabilizer, apparently used in conjunction with a 5108 enlarger. Very nice piece of kit. With one problem – it didn’t work. But I think we got ‘er fixed up again.

The flipside – A closer look at printing color negatives

In previous blogs, I’ve focused on how color paper responds to a light source. When it comes to printing photos, this leaves out a rather relevant bit – the negative. In this blog, I’m going to explore the interactions between light source, negative and color paper. Hopefully, this will give some more insight into which LEDs work best for color printing (although I have a pretty good idea already…)

Twister fries – More RA4 curves, now with a dichroic head

The other day I set up a Durst M305 color enlarger that I temporarily have with me – just to verify it works. Since I had it out anyway, I figured I could make some step wedges with it. I’ve been doing this with LED light sources recently as well. I couldn’t resist the temptation to see what one might get from a dichroic head. It’s still a bit of the gold standard for darkroom color printing, after all.

Unsafe lights – The iffy business of RA4 safelights

Opinions vary on the issue of safelights for RA4 printing. One person says they’re fine, within rather tight boundaries. Others advise against any lighting and recommend working in the dark. I belong to the latter category, and I believe that I have good reasons, too (of course).

Sloppy slopes – Green and blue LEDs for variable contrast black and white

Recently, I wrote about a new RGB LED head for color printing and reported on some step wedge tests I had been doing. The other day I was printing some black & white negatives with this new head, and I ran into some looooong print exposures. This led me to do some additional testing, which yields some interesting (I think) insights.

Opposites attract – Salted paper and cyanotype curves

I was doing a quick classic cyanotype print to verify a paper (Schut Laurier) indeed works on this process. I knew it did as I’ve used it before in this capacity, but I just wanted to make sure before recommended it. This also create the opportunity to plot the response curve, and since I had a salted paper print on my desk as well, a comparison is easy enough to make!

Trans-mission – A parts bin transmission densitometer

I’ve never owned a transmission densitometer. In fact, I consider myself as far too sloppy and undisciplined in the darkroom to be able to put one to good use – so why bother? Then again, sometimes it’s just convenient to be able to take a few quick and dirty measurements on a piece of film. And there’s always the parts bin full of stuff that surely could be fashioned into a densitometer, right? Right.

Perfecting primaries – Another look at LED wavelengths for RA4 paper

Way back I explored the best wavelengths for exposing RA4 paper. In that blog entry, I pitched an idea of optimal wavelengths that I hadn’t tried yet. Well, I picked up the glove myself and I think the results could be pretty relevant. Read on, especially if you’re looking to purchase or build a LED exposure system for color enlargements.

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?