Darkroom Lighting Color Temp considerations

[DennisD]

Thank you to all who replied.

It's clear that LEDs are ok only for general illumination while incandescent (tungsten or halogen) best for more critical viewing with consideration given to CRI if possible.

My setup is such that I have sockets conviently located above the developing trays so incandescent bulbs are no problem.

I've never liked fluorescents or the CFL varieties in the darkroom. The fluorescent afterglow can be a problem.

[Drew Wiley]

They don't fade quickly Randy. These are German, not made in some Taliban cave like Phillips bulbs or consumer GE. The bulbs are dependable for decades. No ballasts - that helps. These are real-deal scientific instrumentation bulbs and would probably cost a hundred bucks apiece today.

[Jac@stafford.net]

If the display of your prints' environment, for example your home or a gallery do not approximate your viewing light from the darkroom, you are at a profound disadvantage. Viewing conditions are critical. If your work is shown as a collection an astute conservator will have the gallery lighting adjusted properly.

[calebarchie]

These are the ones Drew is talking about
https://www.bhphotovideo.com/c/searc...&N=3989452948&

[Drew Wiley]

Well, not quite the same. Mine are even higher rated; but the Just Normlicht 5000 K's are more realistically priced and plenty good. The only minor problem with their own lightboxes per se is that they don't take into account the slight warming of the plexi diffuser, which ideally needs to be offset with a diffusion lining inside which cools the color temp about 200K or so. I've long forgotten the exact figure, but its doable. I have only one such critically calibrated light box; but it's invaluable for matching work like precision dupes. For just sorting color trannies or casual viewing I have a big light box with 1/4 inch sheet glass over it.

[StuartR]

MR16 Halogen track lighting with Solux bulbs. I stick to the 3700 in the darkroom, and use 3700, 4700 and 5000K for print evaluation in the main studio. Solux Halogen gives great CRI (100 for the 5000k), very short afterglow (10 seconds or so), and the track lighting means you can set it up in critical areas without having it light your paper safe as directly etc. It is also dimmable without any constraints, which is helpful for long sheet film loading or printing sessions. Finally, the bulbs are cheap(ish) and last for a long time. I standardized on them in my lab years ago and have been very happy I did ever since.

[Bob Salomon]

I'm in total agreement with Drew here. I try to recreate what I consider to be "normal" gallery lighting in my darkroom. I don't do color prints, so I don't worry to much about getting a daylight reference close to 5000K, rather, I'm concerned with how the toning of the prints will come across under the usual display lighting, which is often a mix of halogen (from the gallery track lighting) and daylight (from the windows/skylights). Therefore, I have a display area in my darkroom where I can hang up my prints for viewing that is lit by a mix of 3400K halogens and one or two daylight floods. This I use for evaluating dry prints for contrast and toning hue. For viewing in the fix, I simply have a 40W halogen bulb in a reflector on the ceiling over the fixer tray.

I wouldn't use LEDs for critical viewing purposes simply because the don't emit a continuous spectrum and can do funny things with colors/toning hues.

Best,

Doremus

Fluorescent tubes also don’t have a continuous color hue!

[Jac@stafford.net]

Fluorescent tubes also don’t have a continuous color hue!

So, their claimed K is in error?

[Drew Wiley]

Bob, if you know where to find em, there are fluorescent tubes with very high CRI values which closely simulate continuous sources, and I don't mean the BS ratings symptomatic of cheap consumer and home center products. They also have the advantage of being cool. Halogen lights can melt cast iron, I suspect. At least it feels like it sometimes. But Solux is a good brand to look at for bulbs. I prefer traditional tungsten track lighting; but certain products have been discontinued due to shortsighted energy consumption concerns which totally overlook the implications of neo-lighting alternatives on human health and safety.

[Bob Salomon]

So, their claimed K is in error?

No, CRI is a different rating the color temperature.