a UV enlarger?

Mainecoonmaniac · Nov 17, 2011

I'm playing with the idea of converting my 45MX to a UV enlarger. There are new LEDs that emit UV light. I'm wondering if it would be practical to try to make a UV enlarger head for cyanotypes with LEDs? I've exposed cyanotypes outside doing contact prints and it can take up over 10 minutes in full sun. I can try to enlarge negs to do contact prints, but with a UV enlarger, I would just skip enlarging the neg.

M Stat · Nov 17, 2011

With a UV enlarger, focusing becomes problamatic. Considering the intensity required for UV enlargment, a standard grain focuser would burn out the retina in your eye, and a closed circuit video system must be employed to enable focusing. The beauty of negative enlargement is that you are able to adjust the contrast of the original negative to whatever level needed for various alternative printing methods.

Hexavalent · Nov 17, 2011

Optics with very good UV transmission would be required; such glass tends to be very $$

The Fresson lab employs enlargers for their process - exposures run in the hours.

steven_e007 · Nov 17, 2011

I've thought about this, too, but never done anything about it. The usual reason for contact printing is that most lenses absorb UV, so the enlarging lens would normally pass such small amounts of UV as to make the developing out time far too long.

Lenses intended for UV are made of quartz or flourite, are very expensive and very rare.

With LEDs you can get quite a lot of UV, I suppose, without all the heat and high voltage of the old bulbs or the ungainliness of long UV fluorescents. As the other APUGer says, though, think about the safety of your eyes.

If you use a conventional lens, then the simpler the lens, the more UV it will pass. A very simple triplet may be a much better bet than a top quality 5 or 6 element job, but only expect to pass a few percent of the light from your LEDs.

So, would very bright LEDs + simple but very fast triplet = a working system?

I've no idea, but I'd be interested to know if you can make it work.

anikin · Nov 17, 2011

Hexavalent is right. Optics is the main problem. Regular glass blocks too much of UV, and you can jack up the power of light source only that much before melting your negative. You need to use a quartz lens for a reasonable exposure time. A lens that covers 35mm is very expensive. I did not find lenses that cover larger formats, but I did not look for too long. Anyway, it's not impossible, just very expensive to do. A very good idea though. I've been long contemplating making one myself.

Another possibility is to use a UV laser as exposure source. Do a raster scan through the negative. Doing that you may reduce need for expensive optics, but the cost of the light source goes up since you need a powerful UV laser (Blue-ray DVD burners, here we come!) and a high-precision raster mechanism. With that approach, an issue of vibration comes up as soon as you introduce moving parts.

I don't think focusing would be too much of a problem. I would coat a sheet of paper with fluorescent paint and use that for focusing.

E76 · Nov 17, 2011

Durst Pro developed a UV lightsource for enlarging on Azo, so it's certainly possible. You are definitely going to need a extremely bright lightsource.

JBrunner · Nov 17, 2011

Could use mirrors instead of lenses.

Mainecoonmaniac · Nov 17, 2011

Wow. I'm learning a lot about UV light and glass. I guess most if not all enlarger lenses are made for the visible spectrum.

Hexavalent · Nov 17, 2011

Another thing to consider is the poor old negative - it's likely to get fried by intense UV; this does happen with Fresson enlargements.

holmburgers · Nov 17, 2011

JBrunner said:
Could use mirrors instead of lenses.

Hey, what about this though? JB might be on to something, there were old cameras that didn't use lenses at all. You could theoretically utilize 100% of the UV with a front surface mirror.

Mainecoonmaniac · Nov 17, 2011

I wonder about that. So the mirror would have to have a convex or concave to focus the image?

John Koehrer · Nov 17, 2011

I believe early enlargers just reflected sunlight through the device. They had one end of the dingus stuck out the window and the other over the printing frame. Just a larger version of the periscope you had when you were a kid.

ic-racer · Nov 17, 2011

Brunner is right. You need a 'reverse' Wolcott camera.

keithwms · Nov 17, 2011

A lot easier just to enlarge your negative and then contact print it...

Newt_on_Swings · Nov 17, 2011

If you made something with such an intense UV light source, it would probably be pretty bad for your eyes =O

Mainecoonmaniac · Nov 17, 2011

I have to admit that it's a dumb idea. APUGers proved it.

richard ide · Nov 17, 2011

I had an enlarger with a 6000W pulsed xenon light source. While experimenting with it, I tried enlarging on to material similar in speed to cyanotype paper. Apart from a very long exposure time (minutes), the image was fuzzy. Just too much light for too long.

steven_e007 · Nov 18, 2011

Mainecoonmaniac said:
I have to admit that it's a dumb idea. APUGers proved it.

No, APUGers haven't proved anything. We suspect it is a very bad idea.

Don't be put off trying a few experiments... LEDs can produce a lot more light for a lot less heat than other light sources.

I still think you will still struggle to get nearly enough light through a conventional lens and I suspect it won't be viable. But... try it and see if you can prove us wrong. There shouldn't be too much effort involved in wiring up ten LEDs and giving it a quick go.

The mirror idea is brilliant, but then you are pretty much chucking your 'convert my existing enlarger' idea out of the window.

2F/2F · Nov 18, 2011

Among other problems, you would have no ability to finely manipulate contrast aside from exposure and development of the in-camera film. Not impossible, but certainly limiting. For one thing, you would have no room for slop in any of your shooting, and no room for later reinterpretation of your intent...i.e. no way to change your mind in the darkroom. For another, cyanotype emulsion varies batch to batch depending on which way the wind is blowing, so the ideal contrast for your negs would be a fugitive thing. For yet another, you would end up with negatives that are very difficult to print on regular silver paper.

How would you hold your coated watercolor paper flat? It can warp a bit when it is coated.

How would you get enough intensity to make for reasonable exposure times? My cyanotypes generally require over 20 minutes of exposure in full-on sunlight. In weak artificial sun, I'd imagine that times could go well beyond an hour. Does cyanotype paper suffer from reciprocity failure? Is it good for your enlarger bellows or for your film for the LEDs to be on that long?

How would you keep from blowing your eyes out focusing? Being in a room with blacklight tubes for even a short time gives my eyes a weird haze. I cannot imagine looking through a grain focuser right at it...and that brings up another point: Can you even properly focus UV by eye?

Aside from the fact that there are a lot of obstacles to overcome to make such a thing, I'd say that there are almost no benefits to your proposed invention in the first place. In other words, there is not even much of a reason to warrant trying to overcome all of the obstacles. You have tons of control, versatility, and latitude using the interpositive method. I'd call it a great tool that should be fully utilized, as opposed to an annoyance that needs to be overcome.

steven_e007 · Nov 18, 2011

2F/2F said:
Among other problems, you would have no ability to finely manipulate contrast aside from exposure and development of the in-camera film. Not impossible, but certainly limiting. For one thing, you would have no room for slop in any of your shooting, and no room for later reinterpretation of your intent...i.e. no way to change your mind in the darkroom. For another, cyanotype emulsion varies batch to batch depending on which way the wind is blowing, so the ideal contrast for your negs would be a fugitive thing. For yet another, you would end up with negatives that are very difficult to print on regular silver paper.

How would you hold your coated watercolor paper flat? It can warp a bit when it is coated.

How would you get enough intensity to make for reasonable exposure times? My cyanotypes generally require over 20 minutes of exposure in full-on sunlight. In weak artificial sun, I'd imagine that times could go well beyond an hour. Does cyanotype paper suffer from reciprocity failure? Is it good for your enlarger bellows or for your film for the LEDs to be on that long?

How would you keep from blowing your eyes out focusing? Being in a room with blacklight tubes for even a short time gives my eyes a weird haze. I cannot imagine looking through a grain focuser right at it...and that brings up another point: Can you even properly focus UV by eye?

Aside from the fact that there are a lot of obstacles to overcome to make such a thing, I'd say that there are almost no benefits to your proposed invention in the first place. In other words, there is not even much of a reason to warrant trying to overcome all of the obstacles. You have tons of control, versatility, and latitude using the interpositive method. I'd call it a great tool that should be fully utilized, as opposed to an annoyance that needs to be overcome.

Hmmm. So, you don't think it is a good idea, then?

M Stat · Nov 18, 2011

And by the way, Durst does NOT make a UV enlarger head. The link provided by another poster was for a 5,000 watt halogen lamp (for use with AZO paper), not UV. I am a personal friend of Jens Jensen and it is true that he designed and developed a UV enlarger some years ago. The intensity from the lamp was strong enough to burn skin within only a few minutes and was deemed too unsafe. He eventurally abandoned the project.

artonpaper · Nov 18, 2011

Prior to deciding to make negatives on an inkjet printer, I would send film to DR5 for reversal processing and then project the positive onto 8 x 10 sheet film. I was using Plus X at that time for the enlarged negatives. You need a good neutral density filter and a bit of patience. Once you work out your exposures, it comes easier. Of course you can make positives from negatives, or do your own reversal processing. But, dare I say on this site, digital negatives work fine.

holmburgers · Nov 18, 2011

Obviously it's not the kind of game changing idea that will revolutionize alt-printintg hereforth, but it's certainly a really cool idea!

It's one thing to have ideas and discuss them, but even regardless of whether it's "good" or not, if someone gives it "the old college try" we ALL benefit from that and we will all learn something and think it's noble work.

It's easy to convince yourself that it's a bad idea, anyone can do that. What really takes guts is having the conviction to give it a go.

I think a mirror lens with high-powered LED's as the UV source would be a noble effort. If anything, to prove that you can do it and to learn a whole boat load in the process.

Mainecoonmaniac · Nov 18, 2011

Thanks! I have another hare-brained idea. I wonder if someone covered themselves with cyanotype emulsion, then used wrapped themselves with a negative and exposed themselves in a tanning bed, would it make a cool tatoo? I don't think I'll try to make a UV enlarger, but possibly a UV box for those rainy days when I want to do alt processes. UV LEDs show a lot of potential.

holmburgers · Nov 18, 2011

What about a plastic lens? I mean, a ton of crappy cameras use them. I believe it is possible to make high quality acrylic lenses as well... I wonder where you could find one for cheap?

a UV enlarger?

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