Registered here because this seemed the right place to ask this technical question, hopefully this is appropriate. So I have been looking around for good consumer LED filament bulbs with acceptable CRI and R9. Came across an OSRAM SST Plus Globe 100 11W/2700K at a local store and picked one up because it said CRI >= 90 on the box. Checked the datasheet on their (Ledvance, the new OSRAM splitoff / divesting thing) site (datasheet here) and there it was, staring right into my face: R9 = 0. Hum.
Then I take the Waveform Lighting Ultra High 95 CRI 2700K filament bulb, photometry report here , they claim an R9 of 80+. But now compare the two spectral power distributions, the one from OSRAM (page 3 on their datasheet) and the one from the Waveform Lighting bulb (sorry I can't manage to post inline images here, or I would have posted a side to side comparison). After roughly renormalizing the OSRAM SPD, both are almost exactly the same ! How can one have an R9 of 0 and the other an R9 of 80, if both spectral power distributions are almost identical ? Look at the distribution on the red end around 650nm and above, they are pretty much identical.
There is absolutely no way that the Osram SPD has a R9 of 0. There must be a mistake, or that Osram is just giving a VERY conservative estimate, like how Nichia rates some of their 90 CRI emitters that are typically 95+ or 97+ in practice.
it could be a typo… suggest you write to the manufacturer and ask for verification (dont hold your breath, you might just get a secretary requoting the data sheet)
and or, find someone with a Spectrophotometer and verify the R9 by direct measurement
Sekonic has a list of dealers at the bottom of this page https://sekonic.com/ maybe you live near one
Thanks, yeah agreed, it looks like a typo or oversight when they created the datasheet. I've reached out to Ledvance, got a pretty quick non-automated reply that they transferred my inquiry to the relevant tech department. Let's see. I hope it turns out to be a mistake. The SPD looks pretty decent and it's not that easy to find good filament style globes.. Waveform doesn't have any as far as I know.
I'm a lighting quality perfectionist. I still use my halogens where I can, but they're getting progressively harder to source these days. I'd love a spectrophotometer. I thought about buying a used one if I can find something not horribly expensive. Maybe like an xrite i1pro, which seems pretty popular together with the osram software.
Not relevant, but I am curious to hear your opinion on neodymium coatings on incan light bulbs. The purpose of the coating is to remove some yellow from the spectrum and make colors look more saturated. General Electric "Reveal" series is an example. Would you prefer a coated light bulb over an uncoated one?