Garage light, color, spectrum

["Mike Nakamura" <mike_nakamura@domain.elided>]

I'm not convinced you need to go too far to extremes for lighting your
ALFA's, but here is some information.

In the graphic arts industry (printing, photography, etc.), ANSI and ISO
standards are 5000 degree Kelvin color temperature and CRI of 91 or better.
The 5000 degree Kelvin is intended to be an average noontime light on earth
(not measuring the sun) and is a good temperature for the human eye. The
notion of a standard is to create uniformity across all viewing conditions
in the industry. The relativity high color-rendering index (CRI) offers
close to full spectrum illumination. This prevents a visual "drop-out" of
certain spectrums. The standards for graphics arts also specify the
intensity, surround colors and open distance around the viewing area for
transparencies.

Many color-viewing booths in the graphics arts industry have a 7500 degree
Kelvin setting which is sometimes used to evaluate slight color differences.
The human eye is slightly more sensitive to some hues at that color
temperature. 7500 degree light is sometimes referred to as North light. ASTM
D1729 calls for 7500 degree K light for evaluation of opaque materials.

Cool white florescent (CWF) is usually 4150 degrees Kelvin.

Some fluorescents are 3000 degree Kelvin.

Standard tungsten light bulbs emit light in the 2200 to 2800 degree Kelvin
range. When you use a dimmer you lower the temperature output.

The best know example of spectrum dropout is using daylight film (you
remember, analog plastic film in antique cameras) under florescent lights;
you get green pictures. The color temperature reading may indicate that the
bulbs are adequate, but the bulbs do not emit part of the red spectrum.
Color temp only readings would suggest that your pictures would be better
than photos taken under tungsten lighting (2800 vs 4150 degrees Kelvin).

CRI is being superceded by a new measurement technique. A quote from GATF.
"The new standard keeps the same CRI criteria but also introduces two new
criteria called the visible and UV metamerism indexes. They are based on a
CIE standard called CIE Publication No. 51, 1981-A method for assessing the
quality of daylight simulators for colorimetry. The indexes use more complex
matching criteria, one for the visible and one for the UV portion of the
spectrum, to further restrict the allowable differences between the actual
spectral output of the D50 simulator and CIE Illuminant D50."
(http://www.gain.net/business_solutions/technical/info008.html)

For most uses in the garage, I believe intensity is more important than
color temperature or CRI. We remodeled our garage and I wanted 3 fixtures in
each bay (3 bay garage) with 2 eight foot bulbs. Our lighting advisor,
electrician and builder all said it was too much, so we went with 4-foot
fixtures. As a back up, insisted on two switched outlets in each bay. Good
thing. The 4-foot fixtures give general walking around lighting, but not
nearly enough for working on a car.

If I were to do it over, I'd use the 8-foot fixtures, put 4 in each bay and
keep the switched outlets. I'd add several more switches to control the
fixtures, don't want all on all the time.

When I wax a car, I put it sideways in two bays, plug in free standing
lights low and high and keep the garage door closed or partly open (keep
direct sunlight off car and balance intensity).

Reviewing the message, I see that I've written way more than you want to
read, I hope it's interesting to a few ALFA people.

http://www.mts.net/~william5/library1.htm is an interesting link (if you
like lighting). I did not confirm all the links or check for accuracy of
information on the site, but it looks pretty good after checking a few
pages.

Mike Nakamura
7414 337th PL SE
Fall City WA 98024 USA
(425) 222-3982
mike_nakamura@domain.elided
91 Spider Veloce
94 164LS
02 Dakota
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided