Beseler enlarger. Exposure changes one day to the next. Ex

[lhalcong]

I have a Beseler 23CII dichro head I use to print color negatives. I had this suspission bothering for a while but now I'm completely sure. The exposure changes from one day to the next. Here is an example. Last night I already had my test strip made. Had my exposure set giving me a good print. I made about four(4) 11x14 prints of this negative exposed for 26 sec @ F/11. I had some minor additional burning to do to make it a "perfect" print. But it was late and decided to stop and continue the next day. Today about 24hrs later I picked up where I left off. Absolutely Nothing changed, nothing was moved. With the same negative at the same height, I made another print with exact same exposure. To my annoyed surprise the print is now much lighter for approximately a stop, to the point that I have to run a new test strip ( I shouldn't have to ). Same batch of chemicals, and Again no variables were changed except that 24hrs have past. What is going on ? And how can I avoid this problem ? The lamp is new. And I believe this was happening with old lamp as well.

 

[Chan Tran]

You need a stabilized power supply. You have voltage flunctuation

 

[Sirius Glass]

You need a stabilized power supply. You have voltage flunctuation

That is it. He broke the code. You have voltage fluctuations.

 

[lhalcong]

I do have a voltage stabilizer.

 

[Sirius Glass]

Have the voltage stabilizer checked out. Also check out the conditions of the switches and wiring.

 

[MattKing]

Has there been a change in temperature of your chemicals?

 

[OzJohn]

Has there been a change in temperature of your chemicals?

Yes, sounds like a processing variation. What's your processing setup - trays, Jobo etc? I guess it's always possible that the lens aperture has been moved. Is it only the density that has changed or the balance too? OzJohn

 

[Rick A]

Just a random thought, as I don't use a dichro head, the halogen bulb was warmed up the previous evening and then used cold the following day. OP spent the evening making several tests and prints which kept the bulb close to operating temperature and shortened the warm up time for each print, then the next day shot with a totally cooled bulb. Might be worth a test. I always warm up my enlarger before making prints, even with a standard bulb.

 

[lhalcong]

Has there been a change in temperature of your chemicals?

No. I process at home temperature , 75F which is very constant. keep in mind this happens from one day to the next, and not exactly always. However, within the same session I don't have this problem.

 

[lhalcong]

Yes, sounds like a processing variation. What's your processing setup - trays, Jobo etc? I guess it's always possible that the lens aperture has been moved. Is it only the density that has changed or the balance too? OzJohn

No processing variation. No variables were changed. I use a Beseler rotary motor. The aperture was not moved. I take notes and this was noted; 26 sec @ F/11 . Had the aperture been moved by accident , I wouldn't have posted this question.

 

[GRHazelton]

Tell me, is a powerful UPS usable as a voltage stabilizer, or is its output still variable.

 

[lhalcong]

Just a random thought, as I don't use a dichro head, the halogen bulb was warmed up the previous evening and then used cold the following day. OP spent the evening making several tests and prints which kept the bulb close to operating temperature and shortened the warm up time for each print, then the next day shot with a totally cooled bulb. Might be worth a test. I always warm up my enlarger before making prints, even with a standard bulb.

Rick , that is correct. That is exactly what I did. the previous session had lasted a few hours and the lamp must've been hot. The next day it was the very first print that shows this problem. In fact, that is pretty much constant , every time I remember having this problem , the same conditions applied. the first print from a new session shows the problem. So this must be it.... If this is the problem, then I should try print this negative again after sufficiently warming up the head and then compare again. if it works, then that's it. correct ? What is recommended time-wise then to warm up a Beseler Dichro Head before starting a new session ?

 

[Sirius Glass]

Just a random thought, as I don't use a dichro head, the halogen bulb was warmed up the previous evening and then used cold the following day. OP spent the evening making several tests and prints which kept the bulb close to operating temperature and shortened the warm up time for each print, then the next day shot with a totally cooled bulb. Might be worth a test. I always warm up my enlarger before making prints, even with a standard bulb.

This would be next on my list after the voltage regulator.