Making an UV enlarger
So I have this old Meopta enlarger lying around which uses a E27 bulb and lately I was thinking if it isn't possible to just replace the bulb with an UV bulb, I searched around and it seems that there are UV bulbs available with the E27 fitting. The idea is that I can just use any negative I want instead of first printing on a a transparent. Anybody has done this before? (somebody must have). And would it work? I guess it would because it's not much different than just using a transparent but maybe some people have an insight into this. Also, would it matter if it emits UV A or UV B (or even C)?
I don't think that will work. Others more knowledgeable than me can give you a technical explanation but I use a UV light box that will take up to an 11x14in negative in a printing frame and it has 8 UV bulbs and a clearance of approx. 2 1/2 to 3 inches from the negative. it also has a cooling fan. I have also used exposure to the sun. I think if you had enough light source in the enlarger heat would be a problem.
Enlarge on to this (process just like a print) then you will have an 8x10 negative to contact print under any UV source.
I don't suppose you have given any thought as to how you might focus a UV image. If you use an optical grain focuser, you will run the risk of permanently damaging the retina in your eye, as UV light is extremely dangerous to sensitive tissue (I don't think an SPF ointment splashed in your eyes would be advisable). Of course you could try to assemble a closed circuit video camera, with monitor, to the eyepiece of the focuser, to which I would say have fun.
Glass only transmits light in the very near UV. In optical equipment used with UV light fused quartz in used rather than ordinary glass.
Even if this idea could work the amount of light impinging on the paper would be rather small compared to a contact print. This would make exposure times very long.
The above says it all. That and one little UV bulb just wouldn't do it. It's interesting that there are reports and pictures of daylight enlargers from the 19th century. These show enlargers that open to the sun. They were sometimes built into a room, sometimes they were free standing and could be adjusted to keep the condensers facing the sun. Those required that the sensitized paper be in something akin to a film holder. I haven't seen any references to what material they were exposing (albumen?), or how long the exposures were.
Originally Posted by Gerald C Koch
If one were to build a UV enlarger I suppose focusing could be done with UV protective glasses and/or a yellow filter.
Zeiss used to make quartz projection eyepieces for microscopes, they were in the catalog for a few decades, total production was something just over 100 units of two different models. No idea what the prices were. There are several current suppliers of UV transmissive optics, but you have to dig a really deep hole in your wallet.
OK, seems that the idea isn't really what I hoped to be. I didn't even think of the grain focuser being that dangerous. Ah well, back to the good old TL tubes I guess.
Heliostats on the roof beamed the sunlight down to the Solar enlargers in the darkroom. The mirror in the heliostat was driven by a clockwork motor to keep the mirror at the correct angle as the sun arced across the sky. The enlargers stayed stationary.
There is the old concept of 'chemical focus' - it dates to the days of wet plate photography. Collodion is sensitive to UV and so after attaining 'visual focus' the camera was racked in a bit. TTBOMK, the amount of adjustment is always a constant distance and doesn't change with magnification.
I think the idea of resurrecting a true 'Solar' enlarger is appealing.
Google heliostat for more
You can make a heliostat from the drive and mount for a small astronomical telescope.
Israel making surgeons with carrying sunlight from a collector to the patient with fiber optical cable. You can do the same , fiber optical wire is cheap , only you need a plier to treat the ends and a ball lens and its apparatus. But hey , havent Edison invented the bulb ? You can buy a laser drilled pinhole and use it as your uv lens. UV will be sharper and have more quality on pinhole.