On Apr 29, 4:49*am, "Geoffrey S. Mendelson"
wrote:
Jim Yanik wrote:
you need color rendering accuracy to READ?

I don't have a way of quantifying it, but a continous source is much easier
for me to use as a reading lamp. So a 20 watt halogen lamp on "low" is
easier to read than an 11 watt flourescent at the same distance.

Flicker frequency? CFLs flicker in the kHz range. Imperceptable.
Bigger difference is incandescents are more of a point light source,
which is easier to read fine details -- including letter fonts --
by.
I still prefer them for paint and finishing work, where I need
more accurate color (halogens are second only to sunlight)
and shadow rendition.

Farther away it works the same way too, but I no longer have an incandesent
lamps except for special purpose ones (reading lamps, photgraphic safelights,
etc) to do an eaual distance comparison.

Bunsen grease spot photometer:
http://users.snip.net/~veraandscienc.../Bunsen_P.html
Essentially a sheet of paper with a grease spot in the
middle.