Saunders Enlarger Problemgreenspun.com : LUSENET : Large format photography : One Thread
I have had a Saunders 4500II enlarger with the VCCE head since January (purchased new). I have been working on a landscape print and pretty much had the steps figured out for a 16x20 print. Last week I made about 8 prints and refocused several times in between with good consistancy between prints. Tonight I went back into the darkroom to make a batch more prints. However, The prints were almost one f stop lighter after following the identical proceedure from the week before. I tried a different batch of paper with the same result. Also changed the developer with no change. I then went to another negative that I know exactly how to print. It also printed about a half f stop lighter. I tested the change in light emitted from the enlarger through my Nikkor EL 150 mm with my spotmeter and found each f stop to be one ev different like it is supposed to be. Anyone with suggestions on the problem. I'm starting to think I need to send the head back.
-- Paul Mongillo (email@example.com), May 26, 2000
Paul: I don't know your complete setup, but the first thing that comes to mind is a change in line voltage. Line voltage can vary from day to day depending upon the demands on the power company. Although the voltage may be within limits for electrical appliances and home lighting, it can effect enlarger lights enough to cause problems. If that is the problem, you may need to go to a regulated power supply for the enlarger. As the weather gets warmer, there is more of a demand for airconditioners, etc. The power company may be able to help determine the problem if it is power supply. You may also want to check the power with a volt meter at the plug in for your enlarger. I may be off base, but I have had power variations in my own darkroom. I use my recorded print times as a start, but I usually have to vary from that time. The problem may be with the print head, but I would check the power supply first. Hope this helps, Doug.
-- Doug Paramore (firstname.lastname@example.org), May 27, 2000.
The Saunders LPL Enlargers as you know use quartz MR16 bulbs as a ligh source. The bulbs have a fairly long life with a constant output. At the end of their useful lifespan they do begin to die and then usually just stop working. The ligt output will taper off somewhat.
I would try replacing the bulb. A fairly inexpensive item. Check your results once again and that should tell you what is going on. I really have a hard time believing that voltage fluctuation will result in a long term problem. Possibly an hour or so but not days.
-- MICHAEL j. kRAVIT (email@example.com), May 27, 2000.
Have you checked the light intensity switch on the head of the saunders? It enables you to reduce the light output by one stop by merely throwing a switch. If accidentally activated it could result in the problems you described. Bob
-- Bob Moulton (firstname.lastname@example.org), May 28, 2000.
I didn't see in the original post where the problem was over several days...It sounded like it was over one printing session. The quartz lights do get smoked up and put out less light as they near the end of their life. However, that problem should have been evident near the end of the last printing session before you began having problems.
-- Doug Paramore (email@example.com), May 30, 2000.
A whole stop seems a bit much for line voltage variation, unless you're in an area prone to poor regulation. I had to get a constant voltage transformer for my 7700 for colour work, but I'd estimate I was only getting 1/3rd stop variations without it. Check the lamp.
-- Pete Andrews (firstname.lastname@example.org), May 31, 2000.