Converting condenser head to"cold light head" via flashed opal glass difusion

[Andre Noble]

Finally inspired by a recent post re: Cold Light v. Condenser and over-perspired from trying to burn in runaway highlights in too prints from "contrasty" negati ves, I am in the middle of converting my Omega D5 condenser head into a diffusio n source in the following manner:

I am placing a piece of diffusion material (flashed opal glass precisely measure d, cut round) in the bottom most part of the condenser assembly, so that it will be situated closest to the negative carrier. Then, because of the light loss f rom the diffusion, I am replacing the standard 75 watt bulb with a more powerful one (a 250 watt for starters, if this runs too hot, then 150 watt).

I am interested in hearing from experienced B&W printers who have made similar c onversions on your experience with it. How did you like the results vs. origina l set up, any drawbacks or other details to be concerned about, etc. Thanks. A ndre Noble

[neil poulsen]

You can always give it a try. I did, but with dismal results. There wasn't nearly enough light with which to print. Perhaps the higher wattage bulb will help, but I wonder.

[Andre Noble]

Neil, could you tell me what type of material were you using for diffusion, and where did you place it along the light path? Andre

[Sergio Ortega]

Andre,

Before anyone gets carried away with this "conversion", be advised it will not work. And it might even set your enlarger on fire if you use the same tranluscent, plexiglass diffusion material found on most real cold light sources.

What makes a cold light a "diffusion light source" is not the diffusion disc/panel located immediately below the light tube grid. I suggest you research more closely what type of light sources cold lights use, the differences between condensor and cold light sources, and also study their designs very carefully.

Before anyone embarks on a similar project, check out Aristo Grid Lamp Products' web site for a clear, concise description of cold lights, what they do, how they're designed (there are some interesting diagrams comparing the two light sources) and their benefits over simple tungsten bulb light sources.

They can be found at: www.aristogrid.com. Good luck, Sergio.

[Doug Paramore]

Andre: I tried to do the same thing about 10 years ago without success. While I was able to diffuse the light a bit, when I got enough diffusion to make a difference in the way the highlights were printed the light was too dim. I was able to find a used cold light head at Midwest Photo Exchange. The Aristo cold lights are not really that expensive brand new. Maybe someone on this great web site has one for sale (I don't). I printed a neg that took considerable burning in of a bright area and printed it with the condenser and diffusion disc. When I got the cold light, it printed with little or no burning in of the same area, and the print was much more brilliant. Spend the money for a cold light head, even if you have to save up for a couple of weeks or so. It really does make a difference in your prints.

Regards,

Doug.

[Andre Noble]

Sergio, I saw the idea from a man known as the "Photo Dr. " from the Photo-Net website medium format forum. He stated he used this precise conversion of his condenser to approximate cold light diffusion with success for many years with his Omega D2, and the results approximated cold light diffusion close to 1/2 stop identical results - I presume he was using normal square (graded) filters in the condenser lamp house. He didn't mention any thing about a fire. (Although his prolific, well researched postings mysteriously stopped near the end of 1999)??? Andre

[Frederick Leif]

I haven't attempted that conversion, having installed an Aristo source in my Besler. However, I would hesitate to increase bulb wattage beyond that recommended by the manufacturer. A 250 watt bulb would generate a lot of heat in the lamp housing and lamp socket, and draw a higher current through the wiring. At least check that the components are rating by UL for the service you're attempting.

[Ellis Vener]

Years ago I tried this too on an Omega D2. I tried opal glass on of, below and in place of the condensors. I also tried using rosco Tough Spun (a diffusion material designed for "hot lights" used for movie and still photography, again on top of and below and both below and abovethe condensors. None of these methods worked, the system just wasn't designed to give even light all the way across the negative and I always ended up with fall off, sometimes in unexpected places.

The heat build up was also increwdible, even with the same wattage bulb as the enlarger was designed with. I reinforce the other poster's warnings about putting in a higher wattage bulb.

I suggest you use a real diffusion head. Many used ones are availible on the market in different stores as well on e-bay and in the photo.net classifieds.

A dichroic color head also works extremely well if you cannot find a "cold light" head.

[Brian Ellis]

Andre - If the other answers aren't enough to discourage you, I'd suggest that your "run away highlights" aren't going to be cured by a diffusion light source or even by a true cold light source for that matter. It sounds as though you're just making negatives that have a density range that is excessive for a condenser enlarger. I'd suggest reducing your development time by 20% - 30% and see what that does to your highlights before making any modifications to your enlarger, paricularly when so many seemingly knowledgeable people don't seem to think it's a good idea.

[Andre Noble]

Dear Brian, Doug, et.al.: I just wanted to report back my initial results of a print I made with this cold light conversion set-up I put together this morning. I have the day off from work as a teacher, so while receiving wise advice to avoid the whole mess altogeher , I instead drove around LA, buying a piece of flashed white diffuse opal glass cut precisely to fit inside the condenser, and also a 250 watt GE enlarger bulb from Freestyle Camera. Total cost: $35. I then put the whole thing together and made an 8x10 print of a fairly-well contrasted 4x5 negative which previously gave me fits (not unlike many other negatives I shot). The initial results I find in the difference of the print diffused vs. Condenser set up is STUNNING!!! - This is my first experience printing B&W with a diffused light source. Regarding the print: First, I don't see anywhere on this print where I need to do spotting - a first! Second, shadows are open, just as they were in original scene, whereas with condenser print, they're unrealistically dark, murky. Sky has a uniform glow in difusion print, whereas in condenser print I usually find it lands either too dark or too light compared with the main subject. (Yes, my knowledge and use of filters for B&W film should be improved upon - and hence rendering of sky tone better). Highlights landed on the paper on test print instead of just remaining a dream. Diffusion print made with #1 filter, condenser print with #00 (and even then, I still had trouble placing higlights - and yes, I know I should have reduced dev 30% with this negative to begin with). To sum up: I think I'm on the right track. Printing with my condenser is just not as rewarding as I intuitively feel many of you more experienced printers feel about your dichroic or cold light printing.

Now it's off to Frye's Electronics for a mini fan to draw heat away from the condenser head, and then a hardware store for insulation for the power cord to protect it from the heat of the head as well. Expected total cost for my "cold light" conversion:$50.00. Andre

PS: Should anyone out there try this conversion too, I assume no liabilty should your darkroom go up like a dry Christmas tree :>)