quick, cheap advice for diffusing light in a condenser enlarger

David Lyga · Jun 23, 2011

I bought a large sheet of drafting film (11 inches X 17 inches) from an art supply store for $1.40. This 'paper' is white plastic, allows much light to come through, and has no pattern that could be picked up on the baseboard. I cut a small piece and put it into my filter tray.

It even allows one to get away with using a regular 100 watt bulb (soft light kind) and, with a razor blade you 'file' off the bottom black writing (wattage, etc). Baseboard lighting is just as consistent as with a dedicated opal bulb. - David Lyga

Mike Wilde · Jun 23, 2011

Rosco and Lee threatrical lighting filter gel manufacturers also have a range of different diffusion materials.

mgb74 · Jun 23, 2011

Mike Wilde said:
Rosco and Lee threatrical lighting filter gel manufacturers also have a range of different diffusion materials.

Might be more predictable, but not nearly as inexpensive as matte acetate (which is probably what the OP is referring to). Matte acetate is also good for diffusing flash.

Rick A · Jun 23, 2011

I've used rice paper in the past.

David Lyga · Jun 23, 2011

This drafting film was so cheap and perfect that I had to relay the message. I took a magnifying glass out and held it to the light to see if I could see any pattern in it (because a pattern would show up on the baseboard at small apertures). There was not. It is a perfect material; it is cheap, white, flexible, and easily cut. And the bonus I mentioned: if you usually use a 211 or 212 bulb you will not have to buy one anymore because a Sylvania Soft White bulb works fine if you cut off (with a razor blade) the bottom etching (wattage information and brand name). Usually, in a condenser enlarger even if the black print is removed the filament shows up on the baseboard, at small apertures, because of the lack of opal coating on the inside of standard, household bulbs. But with this diffusion there is no problem with that happening. I use a dimmer on my enlarger (Meopta 35) and keep the dimmer set at about 90%. As a result, my blubs last about 10 years! The dimmer does not cut down much light and there is only a minor filtration change for color work. - David Lyga.

Rick A · Jun 23, 2011

Thank you David, that is good info for all uf us.

artonpaper · Jun 23, 2011

I've used a similar product in the past. I put in the filter drawer, but I also tried it under the bottom condenser. I think I got a little more diffusion that way, if I remember correctly. Eventually I got a cold light which is my favorite light for B&W printing.

2F/2F · Jun 23, 2011

I use frosted glass that I happened to have around from an old box of enlarger parts that came with my B-22. Something similar could probably be got from a glass shop and cut to size. I put the glass above the top condenser lens.

Also, make sure that the light from your bulb evenly illuminates your condenser. I have had trouble on my B-22's with the fact that the bulb comes in from the side. The stem of the bulb also gives off light, so one side of a print would be about 1/3 or 1/2 half a stop darker than the other side. I had to place a collar of PVC pipe around the base of the bulb to block the light from the stem and even out the illumination.

David Lyga · Jun 24, 2011

Sure, ground glass is fine also, but I wanted to impart a solution that is entirely cheap, effective, easy to cut to size, and solves other aforementioned problems as well. Such is drafting film. These forums are quite effective in brainstorming. - David Lyga

L Gebhardt · Jun 24, 2011

How much light do you lose with the drafting film vs the condensers?

David Lyga · Jun 24, 2011

L Gebhardt: That is one of the things that impressed me most: about one stop light loss.

NOTE: the condensers stay put: they are NOT removed. - David Lyga.

quick, cheap advice for diffusing light in a condenser enlarger

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