[pure-silver] Re: Same Exposure Different Prints?

<eroustom@xxxxxxxxxxx>


The Darkroom Automation meter reads 4.60 with a 0.01 or 0.02
fluctuation. At other times in the day I've seen the reading
dip down to 4.51.


A difference of 0.09 stops in light intensity (4.60 to 4.51)
isn't going to be a very noticeable change in the print density
unless you are using a #5 contrast filter.  For normal paper it
is about 1/5th of a zone.

A difference of 0.01 or 0.02 can be ignored.  Moving around the
darkroom with the enlarger on should produce about the same
change.

It doesn't sound, from the numbers above, that voltage fluctuations
are the cause of print variation.


Will a voltage regulator like the one in the link solve that problem?
http://www.pcconnection.com/IPA/Shop/Product/Detail.htm?sku=459725&oext=1038A&ci_src=14110944&ci_sku=459725


No, it will make things worse.  These things have a multi-tap transformer
and when they sense the voltage sagging they switch to a higher voltage
tap.  If you are sitting on the edge of one of the trigger points they
can turn a 1 volt sag into a 14 volt boost.  They only regulate so the
power stays between 110 and 125V.  You need to be able to regulate to
117V +/- 1volt or so.

The best solution is
http://www.sola-hevi-duty.com/products/powerconditioning/cvs.htm,
rather horribly expensive when new, but available on ebay in large
numbers.  They are very reliable and long-lived.  Don't get one any
larger than you need - they draw full power all the time, doesn't
matter what the load is.  But, from the meter figures you gave above,
unless you want to do sensitometery, you won't notice any difference.

==
Nicholas O. Lindan
http://www.darkroomautomation.com/index2.htm
Darkroom Automation
Cleveland, Ohio 44121

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