Info about cold light for Durst 138

[Larry Gebhardt]

Hi, all.

Found on the bay an interesting but strange cold light made by Durst for 138 enlargers, which seems to replace a condenser on a b&w head and I would like to know if anyone has ever tried this, also which kind of bulb does it take. The seller doesn't even know if it's working, but I think the same idea could maybe be adapted for LED light. Who knows?
Here's the link: http://www.ebay.com/itm/321172934757...84.m1438.l2649

Thanks!

I've taken the idea and created an LED version. I've documented it here http://www.trippingthroughthedark.co...ment/led-head/

I wouldn't bother with this cold light head unless you have a power supply for it, or know how to rig one up.

[JMB]

[QUOTE=Cesar Barreto;1051633]Hi, all.

Found on the bay an interesting but strange cold light made by Durst for 138 enlargers, which seems to replace a condenser on a b&w head and I would like to know if anyone has ever tried this, also which kind of bulb does it take. The seller doesn't even know if it's working, but I think the same idea could maybe be adapted for LED light. Who knows?


Hello Cesar,

I have one. In my view the light is way too weak. I was very disappointed with it, and I never use it. In fact, I think that at one point I tried to take it apart to see if I could put a brighter tube in it. Now it does not work at all.

[resummerfield]

...You can convert your condenser head to a cold light diffuser head by simply taping a sheet of white diffusion gel to the bottom condenser....

+1

[Cesar Barreto]

Hi, all.

My previous experience with diffusers over or under the condensers always led to some sort of uneveness, mainly when printing 5x7 negatives. On my view, Durst condensers are so optimized that anything you do just adds to spoil its efficiency and I'm very concerned about this.
But I'll take a look at the LED alternative and I thank for the link.

[Drew Wiley]

Correctly made diffusers not only have to take into account the light source above, but any potential falloff of illumination in typical working apertures for your specific enlarging lenses. In other words, you might need more than one diffuser. They are typically ground plano-convex from white acrylic. But there are other
ways to improve eveness, like using two diffusers of white sign acrylic. True Lambertian diffusion using white opal glass takes a significant toll on light intensity.

[William Whitaker]

I've posted this before somewhere, but it may merit inclusion here. This is an aluminum plate I had made so I could mount a Zone VI 5x7 VC Cold Light head to my Durst 5x7 enlarger. It's made from 3/8" aluminum plate and replaces the entire condenser head. The ruler is shown for scale. Four 6mm bolts secure the head and are replaced in this case by four 1/4-20 bolts. It was much easier for me to find a 1/4-20 tap than a metric one. The cold light head merely rested on top of the aluminum plate and was secured with gaffer tape. Crude perhaps, but no great precision was required. It was both simple and effective. Cost was minimal; I believe it was under $50. I had it made at a local machine shop.

[Larry Gebhardt]

Hi, all.

My previous experience with diffusers over or under the condensers always led to some sort of uneveness, mainly when printing 5x7 negatives. On my view, Durst condensers are so optimized that anything you do just adds to spoil its efficiency and I'm very concerned about this.
But I'll take a look at the LED alternative and I thank for the link.

I had poor luck with a diffuser under the condensers. It was uneven and relatively dim.

[Drew Wiley]

The easiest way is just to get rid of the condenser head and install a new flange and dedicated cold light. But there are fairly easy ways to put in more powerful
light sources, which might require better ventilation; but doing this might compromise later use as a condenser source per se. Glennview does these kinds of conversions.