Discussion:
Sylvania Skywhite Fluorescent
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a***@general-cathexis.com
2014-02-26 18:16:49 UTC
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Does anyone have an image or link to a spectral chart for this light? If so, please, post it.

I recently purchased a case of Skywhite 48" T8 bulbs with the following specs.:

32 watts
8000 K
2700 lumens
88 CRI

I am favorably impressed by skin tones under this light. Unlike most daylight types, the Skywhite light seems to have slightly too much red instead of much too much green. I think that, if Sylvania also offered Skywhite in CFL and advertised it, along with the health benefits of high temperature lighting, on TV, they could make a fortune. If and when Skywhite becomes available in CFL, I would replace all of my home lighting with Skywhite.
Jeff Waymouth
2014-02-27 11:43:45 UTC
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Try this:

Loading Image...&Title=Spectral%20Power%20Distribution%20Curve&NAED=22594&doctyp=document&wdth=792&hgth=612&Desc=Skywhite%20SPD

Jeff Waymouth
Post by a***@general-cathexis.com
Does anyone have an image or link to a spectral chart for this light? If so, please, post it.
32 watts
8000 K
2700 lumens
88 CRI
I am favorably impressed by skin tones under this light. Unlike most daylight types, the Skywhite light seems to have slightly too much red instead of much too much green. I think that, if Sylvania also offered Skywhite in CFL and advertised it, along with the health benefits of high temperature lighting, on TV, they could make a fortune. If and when Skywhite becomes available in CFL, I would replace all of my home lighting with Skywhite.
Ingo Thies
2014-02-28 16:21:55 UTC
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Hi!
Post by Jeff Waymouth
http://assets.sylvania.com/assetlookup/DAM_Asset_Display.aspx?docurl=http://assets.sylvania.com/assets/images/masters/FL_SPD54%20407c8a29-a541-4e29-823e-fd82b979ee42.gif&Title=Spectral%20Power%20Distribution%20Curve&NAED=22594&doctyp=document&wdth=792&hgth=612&Desc=Skywhite%20SPD
I have analysed the plot with the recipe on Wikipedia[1] after
digitizing it with the *very* useful tool PlotDigitizer (requiring some
handiwork, though). I (very roughly) estimated the error by shifting the
whole plot by about half the line width in all directions and also
trying the effects of increasing/decreasing the peak widths by a similar
amount. Results:

Color temperature: 7634 +/-100 K (claimed 8000 K)
Delta u,v: +0.0002+/-0.0002
This is slightly less green than the D-type standard daylight
illuminants which have about +0.0032, but actually near perfectly
Planckian. However, the CCT is far below real sky tone which is
something between 10000 K and infinity (depending on the weather).

CRI Ra (mean of R1 to R8): 87 (claimed 88)
The particular values (should be taken +/- 2 or so):

Standard sample:
R1: 99
R2: 94
R3: 59
R4: 91
R5: 91
R6: 82
R7: 90
R8: 88

Additional sample:
R09: 53 (actually very good for a FL; most FLs have values near zero!)
R10: 56
R11: 79
R12: 68
R13: 97
R14: 73
R15: 96 (Asian skin tone, non-standard)

[1]
<http://en.wikipedia.org/wiki/Color_rendering_index>
and links therein.

I really wish to have these as powerful CFLs with E27 socket. Currently,
my "hottest" (or "coolest", depending on the point of view) lights are
Megaman Nature Color 6500 K with Ra=92. Very good in the morning, but
definitely too powerful for the evening ;-)

Best wishes,

Ingo
a***@general-cathexis.com
2014-02-28 18:43:23 UTC
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Thank you. Apparently, what I misinterpreted as a small lack of green is actually a complete lack of yellow. Isn't the dip at 560 nm unusual in a fluorescent? According to Loading Image..., GE Reveal incandescent also lacks yellow which suggests that people who like GE Reveal incandescent will also like Sylvania Skylight fluorescent. Thus, offering Skylight as a CFL should be a no brainer.
bud--
2014-03-02 17:44:19 UTC
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Post by a***@general-cathexis.com
Thank you. Apparently, what I misinterpreted as a small lack of green is actually a complete lack of yellow. Isn't the dip at 560 nm unusual in a fluorescent? According to http://ledmuseum.candlepower.us/33/reveal5.gif, GE Reveal incandescent also lacks yellow which suggests that people who like GE Reveal incandescent will also like Sylvania Skylight fluorescent. Thus, offering Skylight as a CFL should be a no brainer.
Looking at the Reveal halogen, they claim a CRI of 100.
How do you remove the yellow and have a CRI of 100?

http://www.dpreview.com/forums/post/22418166
(digital photography review)
says the CRI is about 70 and "unscrupulous bulb mongers push these
horrible bulbs at many different groups."

For a GE Reveal that is "100W replacement" the lamp is 1120 initial lumens
For an incandescent 100W bulb 1600 is a reasonable lumen figure
Why isn't that consumer fraud?

GE says it uses 28% less energy than regular incandescent
but gives you 30% less light

GE says it delivers outstanding energy efficiency
Reveal - 1120L/72W = 15.6L/W
real incandescent - 1600L/100W = 16L/W
How can "outstanding" be less than an ordinary incandescent?
If you remove yellow why wouldn't that decrease the efficiency?
(unless you capture and use the heat - but I believe the yellow is
removed by the glass)

Looks to me like fraudulent and misleading advertizing.
Am I missing something?
Ingo Thies
2014-03-02 18:13:15 UTC
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Post by bud--
Looking at the Reveal halogen, they claim a CRI of 100.
How do you remove the yellow and have a CRI of 100?
http://www.dpreview.com/forums/post/22418166
(digital photography review)
says the CRI is about 70 and "unscrupulous bulb mongers push these
horrible bulbs at many different groups."
I have tested the tabulated (PlotDigitizer) spd of the Reveal buld and
found a CRI of 86 and a CCT of 3600 kelvins, i.e. within the
neutral-white regime. However, I don't know whether the drop at the red
end (responsible to the unusual high CCT) is due to additional absoption
of partial transmission in case of a reflector, or due to inaccuracies
in the measurement setup.

BTW not even standard or halogen incandescents have a CRI=100 since
tungsten is not a perfect blackbody radiator and since the glass bulb
does also absorb parts of the light. However, good incans/halogens
should have a CRI>98 anyway. For example, the truck halogen here

http://www.uef.fi/fi/spectral/artificial-lights

(the first of four artificial light spectra) has, according to the CRI
formulae shown and linked at Wikipedia, has a CRI=98.4 and an R9=94.3.

Best wishes,

Ingo

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