They recommend 2000 lux (D50) for critical appraisal,
which would correspond to your "inspection" zone. However,
this is quite a lot of light, and you may want to use it
at this level just where the inspection takes place.
Is your "design area" for computer work only?
If yes, then ISO 3664 recommends levels below 64 lux. This
is very low (and often not practical) and you may want to
use monitor shields or partitions to limit the light at
workstations.
The spec for the "Natural White 950 Series Metal Halide
fixtures" does look promising. However, the global CRI
alone is not enough for critical color assessment. The
individual indices (called special indices ) of the eight
color patches used to measure the CRI are also important;
they should all be higher than 80.
Also, a light with a good CRI may still be quite metameric
relatively to real daylight (or "real" D50). There is a
specification for this in ISO 3664, expressed as a
"Quality Grade", from "A" to "E". The measurements
required for this spec are not trivial, but can be done
using my company's software and an Eye-One spectro.
By combining the CRI data with the Quality Grade, you
obtain a better analysis of your illumination quality.
I would suggest testing the lamp in question, if possible.
I and others would certainly appreciate feedback.
Alternatives are specialized fluorescents such as the ones
sold by GMB and Just. They cost a lot more than standard
tubes but can be fitted in standard fixtures. You indicate
your ceilings are qute high and it may be appropriate to
hang the fixtures much lower to minimize the cost required
to achieve descent illumination levels. For your
application, I have a slight preference for the GMB tubes
because of their higher output but both are good choices.
Danny Pascale
dpascale AT babelcolor DOT com
www.BabelColor.com
On Fri, 15 Jul 2005 11:59:40 -0400
Charlie Rieger <email@hidden> wrote:
Hello all,
I'm working a specs for a new location, and wanted to
get some input on
lighting for both design and inspection areas.
Specifically, I'm looking for
fixture recommendations as well as optimum lux levels
for a design area (
approx 20 x 25 feet) as well a much larger
inspection/finishing area. The
design area has 10 ft ceilings, and the
inspection/finishing is closer to 30
ft.
At least for the inspection/finishing area I'm looking
at Natural White 950
Series Metal Halide fixtures. The specs look promising.
