some info + Re: How fluorescent bulbs work, simply


Judy Seigel (jseigel@panix.com)
Wed, 16 Jun 1999 15:55:15 -0400 (EDT)


On Wed, 16 Jun 1999, Wayde Allen wrote:

> On Wed, 16 Jun 1999, ken wrote:
>
> > For a price (or quantity) bulb makers will tailor the spectral emission /
> > balance to what ever you may want. If some one does know where the peaks of
> > sensitivity are in the emulsion of their choice it may be possible to target
> > that spectrum. Or is this straining at gnats?
>
> I believe the problem is that we don't really know the spectral
> sensitivity of the processess themselves.

There's also the possibility/probability that "spectral sensitivity" is
affected by variables within the process. Not just in gum printing (tho
very dramatically in that medium) I have found that changes in sizing, in
paper, in pre-coating, in mix, etc. change the character of the "curve" in
a print from a 21-step transmission guide. This no doubt is caused by a
range of factors, but change in "spectral sensitivity" is probable as
well, or at least a good bet.

I'll add that using the two white cards with the holes punched in them to
find the density of whatever part of your negative (or positive either,
for that matter), was explained, illustrated & diagrammed last year in
Post-Factory #1. The article, "Sense and Sensitometry," has, I'm told,
been been quoted & referenced in several works since then. (Is there an
English teacher in the house? "Reference" as a verb is so yucky -- sorry
about that.)

Anyway, pointing this out is NOT shameless promotion -- rather it's
another public service. E-mail me offlist for info on getting your own
copy of that issue & the 2 subsequent ones. When the air clears a bit over
the staging area I shall launch an informational bulletin on #3.

Meanwhile, I tack onto this ON-TOPIC message an off-topic one, for those
still with me: Did anyone read the article in the NY Times a couple of
days ago about how deleting computer information creates a puff of heat
that wastes your computer (& I guess does a slow toast on cosmic
marshmallows) ? Apparently a system now in work will unwind files, as it
were, rather than delete them, so that we & our computers can reamin cool
& live happily ever after -- or words to that effect. I assume this is
old hat to the Linux types out there, but I was certainly amazed. I think
that paper hasn't been recycled yet (talk about your puff of heat!), so I
may be able to reference the reference, if any curious person would like
to inquire (OFFLIST, of course).

cheers,

Judy



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