A short while ago, when i ordered some clear MV lamps from CP lighting, i also noticed they had some small 8w "halophosphate" fluorescents with "low" CRI. Since those wouldn't add to shipping cost, i ordered a few of them from Crompton Lighting. For a while i was using them and thought 'Huh, those aren't bad at all, it's very comfortable light'.
When i was fooling around with my spectroscope and the Aliexpress self ballasted MV lamps i happened to point it at the little fluorescents lighthing up the corners of my room. And well... Turns out, they don't actually seem to be halophospate lamps, unless i've missed some kind of innovation?
Firstly, let's start of with what halophosphate spectra actually look like:
This is a Philips color 29 (530) fluorescent.
https://i.imgur.com/C6tDkVh.jpeg
And here a Norton in color 29.
You can clearly see the mercury spectrum lines, along with a continuum of phosphor emissions. You cannot judge color rendering with the pictures, these types of lamp actually have fairly poor color rendering despite their incandescent-like continuum.
Now, let's see what i bought from CP lighting, the Crompton Halophosphate (literally says so on the box) Warm White:
Well, that looks markedly different, doesn't it? It has an entire extra line between green and blue, and also extra bars in red and orange.
It certainly appears to have extra phosphors in there. However, it is also not *completely* the same as the true 82 CRI lamp spectra i have shown below. The Crompton has the exact same lines as a biphosphor lamp like the SL18. However, the Crompton has a continuum between the lines, while the SL18 or the modern CFL absolutely have no trace of continuum. This is not an artifact of exposure - when i look through the spectroscope with my eye, and switch from the one lamp to the other, i can see it quite clearly.
Can it be, that there is a mixture of halophosphate and biphosphor powder in there?Earlier i also bought a brand new Osram 33-640 fluorescent.
Well i'll be damned. Again a spectrum that looks very much UNlike a 60ish CRI lamp!
Now what do those modern, high CRI spectra look like?
This is a Philips SL18, which according to a contribution of James turned out to be a biphosphor lamp. Exactly identical to the "halophosphate" lamps.
And a modern 2010s era twisted Philips CFL. Again identical.
Please disregard the differences in exposure and focus - it's not that easy to take these pictures through a tiny spectroscope.
So what do you think? Could it be that there are bi/triphosphor lamps, that actually only have a 50-60 CRI and therefore can be sold as 530 or 640 lamps? Or is this just a little oversight by the people who market them, and is the crompton "halophosphate" actually a much better bi/triphosphor lamp? Or are we really seeing a new type of low CRI phosphor mixture that is different from what we're used to?
Either way, i'll continue searching for my crappy old color 29 tubes to bathe my room in that beige light i'm looking for
PS for readers who come across this thread in a decade or so: for convenience in layout's sake i uploaded the pictures on imgur. But if imgur happens to die and the pictures over here break, you can also find them in my gallery on this site