dor123
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| The Osram HQI-TS 70W and 150W /WDL and /NDL, were based on tin, which have high vapor pressure compared to rare-earths. Why they moved to rare-earths in their Excellence series?
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RRK
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| Color rendering index getting better by about 7 points (from ~75 to ~82) for 3000K lamps and tin-based chemistries have poor efficacy due to significant part of tin halide radiated energy is in useless infrared range. Though the color of tin based lamps especially in 4K is somewhat lovely anyway. By the way, only early quartz two-end lamps were based on tin chemistry, later ones non-excellence series(at least in 150W) were rare-earth too.
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« Last Edit: June 16, 2024, 05:55:54 AM by RRK »
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dor123
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I didn't know that tin emits most of its molecular radiation in the IR. And as tin have molecular continuous spectrum radiation, I wouldn't expect that moving to rare-earths, which have linear rich emission, would increase the CRI. But the G12 HQI-T /WDL and /NDL are still in tin and didn't not moved to rare-earths. Also: The Excellence have tipless elliptical arctube, and the original HQI-TS don't have this arctube. Also: My Osram HQI-TS 70W/WDL Excellence, have pinkish color to the light: https://www.lighting-gallery.net/gallery/displayimage.php?pos=-175402 |
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« Last Edit: June 16, 2024, 06:02:45 AM by dor123 »
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RRK
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| Tin halide discharge itself has good CRI by definition, but high color temperature and unimpressive efficiency. In small 3K lamps it is augmented with doses of thallium and sodium (and some lithium, intentionally or not). With 4K lamps, some indium is added too. So resulting spectrum is far from being even, and R9 in rather unimpressive, regardless of rather high emission at far red.
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« Last Edit: June 16, 2024, 06:12:49 AM by RRK »
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RRK
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| For G12 versions, it is likely these had their very happy customers for all the time the lamps were manufactured (~20 years!). Also this burner configuration looks very tricky and once optimized, both Osram and GE did not want to mess with it any further...
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RRK
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But still, single-ended tin MH lamps are very cool, I am definitely guilty of being hoarded a stash of them in different wattages and colors 'while stocks last'  |
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dor123
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| And regarding to the 70W/D and 150W/D, James said me that the original halide chemistry of the /D was Dy-Tl-Cs. The Excellence moved to Dy-In-Tl-Na. Why Osram did this? while the CCT remained 5600K, this lowered the CRI significantly, and the light is much less comfortable for me compared to my Sylvania HSI-TD 70W/D, which have the original chemistry of the Osram HQI-TS 70W/D and 150W/D.
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RRK
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| IMHO, Dy-Tl chemistry tends to turn ugly green easily, probably more in low-powered lamps, and also tends to show metamerism due to strong narrowband green peak. Even in very good lamps like 4500K Ivasaki. I have 150W /D lamp that may be original Osram, or may be imitation, with Dy+Tl+Na+ (Li? Rb?) which gives nice balanced fresh light with ~85 CRI and CCT slightly above 5000K. No green tint and no obvious flaws.
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dor123
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| My now broken Sylvania HSI-TD 70W/D have Dy-Tl-Cs, and there was no problem with greenish light. The light is pure white with a very slight hint of yellow.
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I"m don't speak English well, and rely on online translating to write in this site.
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I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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RRK
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| In my experiences the objects showing most metamerism with Dy-Tl light (Cs seems not to have any meaningful output) are somewhat aged plastics, like my synth keys. These turn some unsightly especially yellow-green color.
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dor123
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@RRK: Cesium is here to fatten the arc which is otherwise very constricted with Dy-Tl alone, which can cause it to be not stable. I discovered that these are mainly the Chinese knockoff of the Osram HQI-BT 400W/D that gets greenish with this chemistry, after Max said me that the Osram HQI-BT 400W/D is white also on mercury ballast (And I've seen this). Also: The Osram HQI-BT 400W/D lamp getting greener with age as the dysprosium getting lost from the arctube.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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