Contact Printing AZOgreenspun.com : LUSENET : Large format photography : One Thread
I have read the papers from Ed Buffaloe and Michael A Smith on AZO printing. As Mr. Smith suggested, I picked up an R40 300W bulb. The bulb has a seemingly significant hot spot in the centre of the light beam. I was wondering if anyone else encountered this and how they overcame it or what are others using. Thanks for any help.
-- Matthew Hoag (firstname.lastname@example.org), April 23, 2002
I print Azo with great results using a simple 100-watt soft white household bulb about 18 inches above the paper; no hot spots.
Average exposure times with ABC pyro developed negatives are 15-20 seconds, which gives plenty of time for burning, dodging, etc.
Hope this helps.
-- David Haynes (email@example.com), April 24, 2002.
I too just use a regular household bulb. Mine is 75 watts, about three feet above the paper, and is in a flood light type reflector purchased at Home Depot for a couple dollars. I don't know if the reflector really serves a useful purpose but I had to put the bulb in something and I thought the reflector might help spread the light evenly. Plus the reflector has a clamp that makes it easy to mount on the shelf above my contact printing frame. My exposure times generally run about 30 seconds with Azo.
It's been a while since I read Michael's paper and he knows a lot more about Azo than I do, but I don't offhand know why you would need a special bulb for Azo and in any event 300 watts sounds like a whole lot of wattage. If I used that much I think my exposure times would only be a couple seconds. Of course exposure times depend not just on the wattage of the bulb but also on how far it is from the paper. The developer also has an effect. I get much shorter times when I use Ilford Universal developer with Azo than I do with Amidol.
In any event, my suggestion would be to just use a normal household bulb of something like 50 to 100 watts and suspend it about two or three feet from the paper. You can check for how evenly the light is distributed across the paper by putting a piece of mat board or any other single color paper over your contact printing frame, turn on the light, then take a meter reading of the four corners and the center of the paper. Ideally there shouldn't be any variation in the reading from corner to corner and in the center but a third of a stop or so probably wouldn't hurt anything. If you get more than that, raise the bulb until you get the same reading in the corners and the center. If raising it high enough to get the same reading everywhere causes your exposure times to be too long then get a stronger bulb.
-- Brian Ellis (firstname.lastname@example.org), April 24, 2002.
I don't have a darkroom, but my bathroom works fine for me: 4 40W clear bulbs a few inches to the left and right of each other, roughly 3-4 feet above the sink. My frame goes on the counter around the sink, and I happen to get good results at about 40 seconds and developed in Dektol (standard working solution) for about a minute. Even with the multiple light sources, and the mirror located below them, it works good enough for me.
I also tried using a 100 W bulb and got good results, but it's much easier for me just to put the frame on the sink and flip on the bathroom lights!
Of course, this setup works fine for me, I'm doing this as a hobby. You might need more "quality control". Just try a few different methods and see what works for you. I have found AZO to be very forgiving, and still produce quality results for my novice hands. I have yet to really screw up exposing/developing AZO... just a few dust specs here and there.
-- J. Marten (email@example.com), April 24, 2002.
I tried a 300 watt bulb about 2.5 to 3 feet above the Azo and "burned" them to a crisp in under 5 seconds. I now use a 25 watt bulb in a reflector like Brian referred to, and it works fine.
-- Ben Calwell (firstname.lastname@example.org), April 25, 2002.
Seems like the consenus is a 300 Watt bulb is too bright. No rules about the brightness of the bulb. Whatever works. Paula and I make negatives that are dense. At 3-3.5 feet distance exposures average 15- 40 seconds. We have never encountered the hot spots you are getting.
-- Michael A. Smith (email@example.com), April 26, 2002.