Daniel J. Stern said:
On Mar 3, 7:13 pm, Victor Roberts wrote: [snip]
I wonder if you could really detect which fixture had a CFL
if you didn't know from the start and didn't see it start
up. Have you ever participated in a blind lamp test?
I frequently play this game when encountering lighting devices in
which upon first glance the light source cannot be seen directly: Can
I correctly identify the type of source, CFL vs. incandescent? I make
up my mind what I think it is, then I go check. I don't keep formal
track of my results, but it seems like I am right about 75 to 80
percent of the time.
Based on the above description, I can immediately infer that either you don't
wear glasses of any sort or if you do, you haven't learned how to use them to
your benefit
Those of us who have been blessed with myopia, have two additional tools at
our disposal:
1) Eyeglasses, which show a mini copy of the spectrum of any source when one
looks around the edge of the lens,
2) Unfocused vision, which allows the eye to make a pretty safe guess on the
color temperature of the source.
Using my glasses I can almost immediately tell whether the source is a CFL vs
incandescent. The gap between the Europeum red fluorescence and the Terbium
green bands around the green Mercury line in CFL's is usually resolvable with
glasses of around 4.0-4.5 diopters, so it actually manifests as a mini gap
consisting of two identical narrow copies of the source, one red and one
green. That's an immediate giveaway for CFL's.
I am hyperopic, with my left eye more so requiring +3.5 diopters. I
like glasses with larger size lenses, and I can easily see this effect
through the upper left and lower left corners of my left lens. Sometimes
I can see this effect through the outer corners of my right lens at +2.75
diopters. Lens material is polycarbonate.
There are some CFLs with color that is "adequately incandescent" (not
excessively greenish nor the more-likely excessively pinkish-purplish and
with suitable CCT), and in fixtures that hide the lamp type well enough I
can only tell by this spectral analysis trickthrough my glasses.
As for what CFLs have a higher rate of "matching incandescent color" in
my experience, I would say:
1) I largely find more favorable non-Sylvania-3000K spirals of wattage
23 watts or less and not of any special whiter color. However, I find the
CCT generally a bit on the low side, and I prefer CCT into the 3,000's
when illumination level is "nice and adequate" and the overall color is
not significantly on the purplish side. (For 3500K or anything else
other than 3000K compact fluorescents, I do not find Sylvania worse than
most others.)
2) I have sensed some trend for electronic ballasts being better than
"magnetic" ballasts. I suspect that the current waveform crests with
magnetic ballasts have reduced efficiency of producing
phosphor-stimulating UV but not a similar efficiency reduction in
producing bluish mercury light, so I suspect that explains why I find some
trend of 2700K CFLs with magnetic ballasts to be slightly more
pinkish-purplish than 2700K CFLs with magnetic ballasts.
I do want to note exceptions to this trend, a little more significantly:
a) 2700K Osram/Sylvania F13DTT from the early 1990's I find more
incandescent-like.
b) GE FLB15 and FLG15 (early 1990's, probably obsolete now) I found more
incandescent-like.
c) 3000K Sylvania CFLs with electronic ballasts I found a bit on the
purplish side.
d) Electronic-ballasted 2700K CFLs of higher wattage (generally 24 watts
or more) or of especially compact bulb size for their wattage I find likely
to be at least a little slightly purplish, although no worse than most
magnetic-ballasted 2700K CFLs.
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One more thing: If there is a room where some lamps are more-greenish
and some are more-purplish and they all have the same CCT and apparent
brightness, it appears to me that the more-greenish ones appear "uglier"
unless known to be incandescent sharing the room with CFLs. I sense that
this has made erring slightly towards pinkish-purplish more tolerable than
erring towards greenish for "warm color" fluorescents.
Any comments on this one?
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- Don Klipstein (
[email protected])