# how do I measure color temperature of uva/b florescent lamps ?



## RNARC1

I have been trying to figure out how do I measure color temperature of uva/b florescent lamps ?
I have a lot of different kinds of uva/b linear lights 18 - 36 inches long.
So when I look at normal linear florescent lights they might have a color temp of 4500 like lights of America bulbs.
of course reptile lights do not, how ever some do not look white the bulbs seem to have different colors, some white, some pink and some blue.
even 1 cheap bulb made for ge in china looked to have almost yellow light coming off it.
of course I can see some thing is off but what is their color temp ?
when I went to look at color meters they are of course expensive unless you can find some kind of deal, so I got a 1960's gossenmeter.
which is made for photography, it is analog but seems to be working.
when I tried it on a exo terra bulb it seems the reading goes higher the closer I get to the bulb kind of like a lux meter.
that makes me wonder how color temp of florescent bulbs is measured correctly.
i'm not sure if I should set up a dark room with a test light that has a set color temp like the lights of america bulb that says it is 4500, measure distance to bulb and make the set distance when the gossenmeter hits 4500, then measure the other bulbs from the same distance under the same conditions if that will tell me their correct color temp.

any ideas ?


----------



## geoturtle

I would probably use my camera (dSLR) and a grey card, then get the temp from Lightroom (the processing software) when setting the white balance. If you aren't a photographer, do you know someone who is?


----------



## lucca brassi

http://www.eit.com/instruments/UVMeasurementForFormulatorsPart1_RadTech.pdf


----------



## ssanasisredna

RNARC1 said:


> I have been trying to figure out how do I measure color temperature of uva/b florescent lamps ?
> I have a lot of different kinds of uva/b linear lights 18 - 36 inches long.
> So when I look at normal linear florescent lights they might have a color temp of 4500 like lights of America bulbs.
> of course reptile lights do not, how ever some do not look white the bulbs seem to have different colors, some white, some pink and some blue.
> even 1 cheap bulb made for ge in china looked to have almost yellow light coming off it.
> of course I can see some thing is off but what is their color temp ?
> when I went to look at color meters they are of course expensive unless you can find some kind of deal, so I got a 1960's gossenmeter.
> which is made for photography, it is analog but seems to be working.
> when I tried it on a exo terra bulb it seems the reading goes higher the closer I get to the bulb kind of like a lux meter.
> that makes me wonder how color temp of florescent bulbs is measured correctly.
> i'm not sure if I should set up a dark room with a test light that has a set color temp like the lights of america bulb that says it is 4500, measure distance to bulb and make the set distance when the gossenmeter hits 4500, then measure the other bulbs from the same distance under the same conditions if that will tell me their correct color temp.
> 
> any ideas ?



Given it's a UVA/UCB lamp, CCT is really not a meaningful term. That is a term that applies to visible light. As they emit some visible perhaps you can arrive at a number, but it's meaning is suspect. The easiest thing to do would be to get the spectrum from the supplier and calculate it from the spectrum.


----------

