[pure-silver] Re: Same Exposure Different Prints?
----- Original Message ----- From: <eroustom@xxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Saturday, July 05, 2008 8:42 AM
Subject: [pure-silver] Re: Same Exposure Different Prints?
That's an interesting theory. They're all interesting, thank you for the input all. I forgot to mention that I use a Durst 606 condenser enlarger with an incandescent 150 watt bulb. 
Do these bulbs vary light strength based on heat?
The first print usually comes after much on-off for focusing and light reading and composing. The second print comes after about 10-15 minutes. 

E.
Indescant lamps do not vary in output with temperature as do gasseous discharge lamps. However, they _are_ sensitive to voltage. I suggest getting a cheap voltmeter and monitoring the line. Voltage variations vary all over the place depending on your electricity supplier and the wiring in your house. If this turns out the be the problem there are a couple of ways around it. I think Nicholas Lindan's timer compensates for varying brightness, he can confirm this, another is a Sola constant voltage transformer. I also agree that checking out the lamp wiring and socket is worth doing. Also check the voltage coming out of the timer as well as the line voltage. Since B&W prints are developed to "completion", meaning until the contrast is maximum, there is likely to be little variation from small changes in developing time provided you develop long enough to reach this point. RC papers with incorporated developer (those intended to be usable in rapid access processing machines) will develop fully in one minute in a strong developer like Dektol. Papers without developer need at least 90 seconds and two minutes is a better routine time. Exposure should be based on these times. Temperature makes some difference but is not very critical provided its not unusually high or low and assuming that it does not vary a lot or very quickly, either of which would be very unusual. More information on your developing routine would be useful. 

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Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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