Making an UV enlarger

[Uncle Goose]

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)?

 

[jeffreyg]

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.

http://www.jeffreyglasser.com/

 

[ic-racer]

Enlarge on to this (process just like a print) then you will have an 8x10 negative to contact print under any UV source.

 

[M Stat]

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.

 

[Gerald C Koch]

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.

 

[artonpaper]

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.

If one were to build a UV enlarger I suppose focusing could be done with UV protective glasses and/or a yellow filter.

 

[Bob-D659]

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.

 

[Uncle Goose]

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.

 

[Nicholas Lindan]

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.

Dead Link Removed

Google heliostat for more

You can make a heliostat from the drive and mount for a small astronomical telescope.

 

[Mustafa Umut Sarac]

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.

Umut

 

[BJ68]

Half OT:

Playing around with UV-LED-Arrays see https://illumina-chemie.de/viewtopic.php?p=81452#p81452 (in German)....which I want to use for UV induced fluorescence photography see e.g. https://www.donkom.ca/category/ultraviolet/

Perhaps it´s possible to use it for the UV source in an enlarger....

Links: See Point "B) LEDs" in
https://illumina-chemie.de/viewtopic.php?p=82013#p82013
and
https://illumina-chemie.de/viewtopic.php?p=82015#p82015

Next weekend I will assemble the 100 W UV LED Array....and test it....plus look if the arrays are useful for cyanotype (if I have enough time)...

bj68

 

[radiant]

How much does enlarger lens cut down the light? For example if aperture is at f8? Of course compared to direct UV array or "panel" light.

 

[J 3]

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.

Glass does let much of the UV used in alt process to go through but blocks the UV C that isn't generally used anyway. Fused quartz is used for UV C applications I think.
What blocks ultraviolet are the coatings on lenses. Thankfully many enlarger lenses are simple and uncoated.

This idea was performed successfully a while back with a high wattage UV Led (100 watts or something). There is a thread somewhere of the person that did it. Magnification is severely limited but it can work (barely). It'll never work like a normal enlarger though. Lenses have to be used wide open (soft image), exposure times are large, cooling requirements are severe, and you're probably doing damage to the source negative at these exposure levels (breaking down the plastic in the negative, unless you are using glass of course).

 

[J 3]

P.S. In addition to solar enlargers, and high powered single die LEDs I've also heard of people back in the day using high powered arc lamps of the kind used for search lights for carbon processes with large negatives. It's possible, but not very practical.

 

[DREW WILEY]

Unless it's just a casual intermittent application, high-UV eats up everything inside an enlarger lamp housing. You'd want to replace every foam rubber light seal with a pure silicone equivalent (I do that even with ordinary halogen colorheads, because it lasts). No need to hunt down exotic enlarging lenses - regular El Nikkors are designed to pass sufficient UV. Then, most important of all, you have to figure out how to protect your eyes when operating something like this. You'd want a safer secondary kind of light installed for sake of composition and focus. UV enlargers have been commercially-made, and were big, heavy, and expensive. At one time they factored in the printing industry for certain specialty applications, but ran hot and sometimes required a water-cooled jacket around the lamp housing. The Fresson technique still uses an ancient carbon arc enlarger. Lots of possibilities. But nowadays most people enlarge onto film itself, then contact-print from that, or make the intermediate enlarged negative digitally. Certain relevant intermediate films have been revived since this thread began a decade ago.

 

[voceumana]

Also, enlarging lenses are not usually corrected to focus UV at the same plane as visible light.

 

[DREW WILEY]

That's the kind of issue that those dark blue eyepiece filters which accompanied classic grain magnifiers were meant for - not specifically UV, but blue-sensitive media; but close enough. Any hypothetical correction for focus shift would be easy enough to test for, just like how many camera lenses have an IR focus correction mark the opposite direction. Reasonably stopped down, it's a non-issue anyway. Yet that still leads us back to the greater question, how to do that kind of thing without damaging your eyes.

 

[Lachlan Young]

The Fresson technique still uses an ancient carbon arc enlarger.

I recall seeing some footage of it which seemed to show it using plain old chrome barrel Componon lenses - quite an eccentric machine & like anything using carbon arcs probably producing an atmosphere heavy with ozone. Again, from what I recall of it, it looked awfully like it had been cobbled together from some old enlarging cameras & lantern slide projectors pointing in different directions for different formats/ enlargements, with the carbon arc at its centre as a defacto point source. I think most of the time, the seps are made via contact, rather than any intermediate enlarging at that stage.

Given the real risks of people burning their retinas staring into UV light sources in enlargers, I'd be inclined to say that the only real debate should be whether to make a contact positive, then enlarge to final neg, or enlarged positive, contact for final neg...

 

[voceumana]

You can't focus UV with the eye because you can't see it. You would need something that converts UV to visible light, like fluorescent paint. Maybe you could paint the easel and then use the bare easel to focus? That would probably resolve the lens focus shift issue as well.

 

[DREW WILEY]

We're not speaking about UV "Blacklight". For enlarger usage, bulbs are going to throw out a lot of bright white light and heat too - plenty visible. But yeah, you could hypothetically swing a dense blocking filter over the lens, like some enlarger are equipped to do. Or use welder-style googles. I don't really like either of those ideas. Some of my Durst carriers have target focus devices built in for sake of pre-focus. And yes, the common yellow paint on a Saunders metal easel, for example, would absorb much of that end of the spectrum. But critical focus via a grain magnifier would still be a distinct risk. I once researched all this and drew up prototypes designs, even visited someone who built commercial versions of these, then backed off once he realized all the liability insurance involved. Fire hazard is another risk.

UV-emitting LED's are a more complicated topic for enlarging per se, and probably in routine fashion are just too weak for the very slow alt printing media likely to be involved. But someone else will no doubt research that aspect, if they haven't done so already.

 

[ProfessorC1983]

I was the one who posted the thread a while back about this, and yes, concluded that it "just barely" works. I used this 100W UV LED surface-mount chip: https://www.amazon.com/Chanzon-Ultraviolet-30V-34V-Components-Lighting/dp/B01DBZI4SA -- after trying a few different wavelengths, the 395nm seemed to work best as anything narrower seemed to get eaten up by the condensers and enlarging lens (I primarily used a f/3.5 Rodenstock El-Omegar but I understand the El-Nikkors also pass a decent amount of near-UV).

Focusing was not a major issue as I simply focused with the regular white light bulb before switching to the UV head which I designed and 3D-printed. My cyanotypes at least have all been decently sharp.

The bigger problem of course was heat causing the negative to warp in the glassless carrier. I solved that to some extent by making a double-sided glass carrier, but with 30-40 minute exposure times for an 8" square print, it still made me nervous about using any especially valuable negatives.

There were also some issues with light falloff at the corners which I suspect could be solved by tuning the distance between the LED and the condenser.

I put the project on hold for the time being because I managed to burn out my last LED chip by forgetting to turn on the cooling fan during an exposure... not a mistake one makes twice. However I think I've maximized the results from my Frankenstein'ed Omega B600 and need to move on to designing a custom negative stage, which would allow switching from condensers to a diffuser (Edmund Optics carries ground fused silica panels that should work splendidly), as well as adding a small cooling fan between the diffuser and the negative carrier.

Longer term I think the limiting factor will be the attenuation of the enlarging lens... I'm trying to study up on optical design to see how practical it would be to create a UV enlarging lens from some of the elements Edmunds carries that are color corrected down to 220nm.

 

[BJ68]

Dear All, completed the work...

a) The 100 W-LED array:
https://illumina-chemie.de/viewtopic.php?p=82160#p82160

b) Bar chart for comparison:
https://illumina-chemie.de/viewtopic.php?p=82162#p82162

c) Cyanotype-Mixture-Testing:
https://illumina-chemie.de/viewtopic.php?p=82205#p82205

bj68

 

[radiant]

Dear All, completed the work...

a) The 100 W-LED array:
https://illumina-chemie.de/viewtopic.php?p=82160#p82160

b) Bar chart for comparison:
https://illumina-chemie.de/viewtopic.php?p=82162#p82162

c) Cyanotype-Mixture-Testing:
https://illumina-chemie.de/viewtopic.php?p=82205#p82205

bj68

I thought you were making enlarger but that is basically UV light source?

 

[BJ68]

Yes....but a very strong one....

For enlarger I have to do a little more research how to build it.....with this light source...

bj68


Edit: I have a few enlarger lenses @home...so I will measure them and try it out....

 

[ProfessorC1983]

@BJ68 In your results, when you specify "with filter" are you referring to the glass focusing lens that attaches to the LED heatsink? I performed all of my tests with the lens attached because of more consistent coverage in the corners (I tried both the 60 and 120-degree angles and found little difference), but your results seem to indicate the lens is attenuating quite a bit more UV than I had realized. This has renewed my curiosity in trying out the diffuser design I had in mind which would eliminate all but a single ground glass between the UV and negative stage. I may have a chance to play around with it later this week and will surely report back!