Hi Earl,
I wouldn't worry about reciprocity at this stage, unless you get into very long metered exposure times. This is not meant to say that it should be ignored, but it can play some very strange tricks on your exposure and it needs to be well controlled.
"Tom Miller" said:
I've found that papers vary widely in sensitivity to light: in one camera
> that I use a lot, Kodak P-Max Art RC has an exposure of 8 seconds in bright
> sun, whereas Cachet RC warm-tone matte needs 45 seconds (about 2 1/2 more
> stops).
This is a very important point. Each paper has its own peculiarities and it's a good idea to keep a record for yourself if you decide to experiment with different papers.
But the central point that has not been mentionned is that paper emulsion is manufactured to react to yellow light (enlarger bulb) and not blue light (daylight). It will react very differenttly under sunshine and cloudy conditions in terms of BOTH exposure time AND constrast.
In fact, if you are a bit familiar with technical litterature, Ilford has a very good PDF document that is easy to read on the subject of contrast and light sensitivity of VC emulsions at
http://www.ilford.com/html/us_english/pdf/Cont.pdf
One of the point that is made is that the emulsion speed varies with contrast and contrast is controlled by the light "temperature" (read blueness or yellowness). So is you shoot under sunshine conditions, it helps to use a yellow filter to reduce contrast on your paper negative but then you need top factor this into your exposure calculations...
Chuck Flagg said:
"I should mention I am a shoot by the seat of the pants kind of pinholer."
Me too...! -:))
Of course, one goes through a few pairs of pants to get there!
Best wishes,
Guy
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Received on Wed Mar 17 05:04:03 2004
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