Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "kingdex1"
<king@k...> wrote:
>
> I am building a print viewing cubicle for both black and white and
color prints 

[snip]

> to recommend. Said I had to be more specific. Can anyone here help
me be "more specific?"

Sure. Is this specific enough?

DO NOT BUY A COMMERCIAL FIXTURE!

OK, I know that's shouting. It needs to be shouted.

There are weird "energy saving" laws in both Europe and the US that
require all commercial fixtures to be set up with ballasts that do not
run the bulbs at 100% "ballast factor". The ballast factor is
basically the percentage of rated power you're going to attempt to
drive the lamp to produce. Lower ballast factors (70% is typical)
cause fluorescent tubes (even the best, most exotic tubes) to have the
wrong color temperature, and lower CRI (color rendition index, the
number that tells you how accurately you can judge and compare colors
under that light) than they're rated for.

That's one reason commercial print viewing booths cost so much,
because the people who make them know how to get around this problem.

Fortunately, there is a high quality, low cost solution. It involves
scrounging stuff from at least two different sources, and the
knowledge and ability to rewire a fluorescent light fixture. If you
don't have this knowledge and ability, trade some prints or
photographic services with someone who does. This isn't printmaking,
where the greatest danger is an ink stain or a paper cut. This is
electricity. Horrible things happen when you don't know what you're
doing. People die, houses burn, etc.

One more time. If you don't have the skills to do this wiring safely,
get someone who does.

To get high CRI fluorescents to deliver the high CRI that they were
actually built for, you have to learn about the weird world of
"overdrive" ballasts. Typically, an overdrive ballast drives the bulbs
past their rated power (I use about 130% drive in the blacklights for
my alternative process work and my blacklight bodypainting). But I
found a nice $19 ballast, the GE/Universal B432I120RH, that is built
to drive four T-8 bulbs, and will happily run less bulbs at a higher
ballast factor. With three bulbs, you get a 94% ballast factor. Let's
call that "near overdrive". It's not a perfect 100% drive, but it's
close enough to get the bulbs up close to their rated CRI. As an added
bonus, you can get it off-the-shelf from places like Home Depot.

Unlike other overdrive solutions, GE actually approves the B432I120RH
for 3 bulb use.

http://www.gelighting.com/na/business_lighting/education_resources/literature_library/ballast/downloads/specs/Electronic_Fluorescent/Other_T8/B432IxxxRH-A.pdf

There are other ballasts that can give you a perfect 100% ballast
factor, but the cheapest I know of is $45 for a 2 bulb ballast.

Also, at Home Depot, get 3 bulb T-8 fixtures. Those will have cheap
and crappy ballasts. Discard the ballasts. Save the sockets (and
plenty of wire). Get wire-nuts, you'll need them. The wire in a
fluorescent fixture isn't like off-the-shelf wire from Home Depot.
It's got 1000V insulation. This is necessary to start the bulbs
without arcing. Do not substitute other wire.

The bulb is a F32T8/TL950 Philips 4 foot T-8 (1 inch high efficiency)
32W 5000K CRI 98 (near perfect color rendering) bulbs. These are not
availiable at home depot, but are availiable at any decent electrical
supply. I get mine at Allen Electric (which doesn't help you, unless
you live in the western suburbs of Detroit) when I want a local
source. When I feel like ordering 4 foot fluorescents on-line, I get
them from bulbs.com, who only sells them in a case of 25. Three per
fixture.

My viewing area (it's not a "box") uses two complete fixtures (6
bulbs, 200w total) hanging low over the workbench. The rest of my work
area is lit by two more 3 bulb fixtures, in exactly the same
"overdrive" configuration. Not only are the Philips bulbs perfect for
viewing prints, but they're supposed to be so close to sunlight that
they make you feel good. Does this work? I'm not sure. I think so. It
could be a placebo effect. ;)

I also use them in "cold hot lights", 8 bulbs per 2 foot x 4 foot
panel. That's why I can consume a case of 25 ;)

One last time. If you don't have the skills to do this wiring safely,
get someone who does. There's only one kind of wiring advice you
should take from some faceless guy off the Internet, and that's "get
professional help with the wiring".