The only problem to the Solux bulbs is always the beam distribution, nothing I was ever able to do about that, sadly. That is, the center of the beam has the best chromaticity, 4700K to 5000K, but rapidly falls off as we move away from the center. That is true in my experience for all the various generations of the bulb. Best / Roger -----Original Message----- From: colorsync-users-bounces+graxx=videotron.ca@lists.apple.com [mailto:colorsync-users-bounces+graxx=videotron.ca@lists.apple.com] On Behalf Of Robin Myers Sent: Monday, July 1, 2013 2:52 PM To: colorsync-users@lists.apple.com Subject: Re: Do SoLux bulbs meet color temp specs? Since this issue was raised, I have delved deeper into the issue. It seems that the fixture may have the biggest effect on the CCT for Solux bulbs. Their claim to fame is producing close to a daylight spectral distribution of 4700K (or 5000K in newer bulbs) by reflecting much of the red and IR energy through the back of the bulb. However, this then depends on the light fixture trapping this NIR-IR light and not permitting it to reflect toward the fixture's front. In all the fixtures I have used, except one, the back transmitted light is not fully contained or absorbed. The benefit of Solux bulbs is their MR-16 form factor, allowing them to be used in standard track lighting fixtures for artwork or commercial displays. Placing additional constraints of needing specific fixtures to get the advertised CCT defeats their purpose and severely limits their use. All the measurements I made were made with a standard track lighting fixture with a black anodized aluminum shield to absorb and block as much of the Solux's back transmitted light as possible. Yet there was still enough light reflected forward to lower the CCT by about 200K. I also repeated the experiment with a desk lamp fixture purchased from Solux.net and marketed for use with the Solux bulbs. The results were the same as with the standard track light fixture previously mentioned. What is even more interesting is that the 5000K Solux bulbs with the black coating, designed for use in pendant and other fixtures without shields, produced CCT values about 4670K, or 330K lower than advertised. So even with a black absorbent coating and the black shield/absorber the CCT was reduced. All these measurements were performed in a completely darkened room to make sure the lamp under test was the only light source measured. The best fixtures I have ever used for the Solux bulbs are the Sun Spots from North Light Products. These are a set of custom designed MR-16 fixtures for tabletop product photography. Each fixture blocks all the bulb's back transmitted light and is equipped with a fan which keeps the housing cool enough for unprotected hand positioning. The Sun Spots use the original 4700K Solux bulbs, but driven at a higher voltage to increase the CCT, which when measured at full power produced a 4824K CCT. As Andrew Rodney has said, the CCT discrepancy is not the important thing. The Solux bulbs deliver a better spectral light emittance than any other tungsten or tungsten-halogen bulb. They deliver great quality light and should be judged on this alone, not the CCT spec. Robin Myers rmimaging.com On Jul 1, 2013, at 9:41 AM, Andrew Rodney wrote:
My own measurements and information supplied by SoLux and the Intertek test
lab indicate that SoLux bulbs meet their color temp spec within +/- 200K.
On Jul 1, 2013, at 10:07 AM, Nipat Paiboonponpong <dyenamix@yahoo.com> wrote:
I remember I measured it with Eye One Display 2 long ago and felt a bit disappointed (I didn't know what to expect then). It read 4400-4500K, I had got the 4700K ones.
This was discussed in some lenght back in Feb of 2009 on this list. Franz who asks was provided the posts by Robin Myers and Tim Vitale who both posted very close values that didn't match the spec's! In fact, Robin used a very expensive spectroradiometer along with an i1Pro like Tim and the values they produced were rather close. When this was presented to Franz who asked about this on PhotoNet his reply was (and I quote): "Next, measuring SoLux CCT numbers. There are a lot of wrong ways to measure them and I'm pretty sure the two gentlemen you refer to are doing it wrong". Franz has posted this question to three sites** and has been given the same answers: No, the CCT values don't match what the spec suggests and he will never be satisfied until he hears what he wants to hear.
Further, last week I measured my Solux CCT 4700K bulbs within a Solux supplied task lamp (such that Franz could not say it was a 3rd party housing that caused the numbers he doesn’t what to hear). I used the newer i1Pro-2 and BabelColor CT&A, the results were again very close to Tim and Robin's (4312K) which Franz equally ignored.
Best thing to do is ignore Franz as he's not interested in hearing anything but what his 10 year old Minolta Color Meter showed: a value within CCT 50K of spec. I tried to explain his device is far, far from ideal but, he isn't interested in hearing any facts based on science let alone colorimetry. He's sure the Solux numbers are correct and when shown they are not, suggests anyone who presents them contact Solux to learn what they did wrong. If you read any of his posts, it becomes quite clear he's a flat-earther. I don't think we'll hear from him here fortunately as he's decided to remain silent on the other two forums after having his behind handed to him <g>.
It WOULD interesting to hear from Solux who is also posting an article by him and haven't said anything about the discrepancies in CCT values. That said, who cares (besides Franz)? The output of the Solux bulbs are lovely and the numbers reported don't mean very much anyway.
** Franz's rants:
http://photo.net/digital-darkroom-forum/00bjDL http://photo.net/digital-darkroom-forum/00bkvN http://www.luminous-landscape.com/forum/index.php?topic=79604.40
Andrew Rodney http://www.digitaldog.net/
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