Judy Seigel (jseigel@panix.com)
Tue, 13 Apr 1999 22:01:19 -0400 (EDT)
On Wed, 14 Apr 1999, Liam Lawless wrote:
> answers that say pretty much all I'd have done, but I'd like to add that it
> was not a good idea to list flash times as percentages of the main exposure
> because, as I soon found out, the flash necessary to achieve a given maximum
> density can vary greatly with the densities of original negatives. The
> figures were only intended as a rough guide, but they seem to have proved
> misleading.
I think Liam is being very kind here, because, as I recall, he had
eliminated any "suggested figures," and I put them back in, thinking that
some guide would be better than none (& who knows maybe it was). My
understanding, though, Liam, was that you were working on another method
to calculate flash... is that in the pipeline, or am I confusing that with
something else?
> ..... Judy's suggestion of a separate flashing light is an
> excellent one, but I wanted, originally, to make the method as simple as
> possible, and what could be simpler than using the enlarger to flash, at the
> same aperture as used for the base exposure? Stopping down probably isn't
> an option as you were already working at f/32, but cutting down the
> intensity of the flashing light does permit more control by increasing flash
> times. Since writing the article, I have wired my (mains-powered) enlarger
> through a dimmer switch for this reason, though another way would be to use
> neutral density or variable-contrast printing filters under the lens. Since
> the flash time is established by test strip, it is not even necessary to
> know the filter factor of whatever you use (though the 10 to 50 percent of
> normal exposure rule would no longer work).
There's no doubt in my mind that a separate flashing light is a great
amenity -- EXCEPT it would require one extra step in this case. If you're
going to flash for any factor of the exposure light, you have to establish
some kind of ratio between the flashing light & the enlarger light. I'm
not the kind of person who could derive that *theoretically,* but I
imagine it ought to be establishable in a test strip easily enough....
Or I guess those who have one would use an enlarging meter?
> A big, unexpected advantage of my dimmer switch is that with it set so that
> I can work at f/11, my enlarged negs are significantly sharper and brighter
> than they were at f/32. The reason for this is that lenses are generally
> reckoned to perform best a stop or two down from their maximum aperture
> (mine is a f/5.6 Componon), something I had not previously considered.
Liam, how come you were at f-32??? Is your bulb very bright? Or was your
original very thin? As I recall we did f8 with the same film, at most
f-11. Do you have stronger electricity? Working smaller?
Judy
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