How to calculate the k (colour temp) of a combination of bulbs?

duncangweller · #1 09-11-2013, 04:27 AM

Hi All,

I am coming up to needing to replace 3 (of 6) of my t5 bulbs and I have been reading a lot about color temperature and growth rates etc etc.

However, all the info refers to 10k, 14k or 20k lighting. If you have 6 bulbs all with different color temperature then how to you come up with an overall figure? Is it just an average?

Hope someone can ear this up for me.

Ta,
Dunc

Sent from my Nexus 4 using Tapatalk 4

tang daddy · #2 09-11-2013, 08:23 AM

Well it's pretty much a guess.

If you had 4 blue 2 white 16k
3 blue 2 white 1 purple 14k
4 blue 1 white 1 purple 18k
4 blue 2 purple 20k

Hope it gives you an idea......

kien · #3 09-11-2013, 02:27 PM

I really don't know the answer to this either so I'll just talk out my arse..

If it were me, I would just take an average. The bulbs are rated at a certain temperature, and since light is additive, it would stand to reason that you could average them together ? Mind you, I have no clue what a fiji purple bulb's temperature would be..

Magickiwi · #4 09-11-2013, 03:06 PM

I think a Fuji purple is 420nm.

tang daddy · #5 09-11-2013, 03:12 PM

Fuji apples.....

Fiji purple is 15k same as the Ati purple plus.

kien · #6 09-11-2013, 03:14 PM

Quote:

Originally Posted by Magickiwi

I think a Fuji purple is 420nm.

I have no idea what the wavelength of the fiji purple bulb is either. If I recall correctly that bulb's spectral graph peaks in two places, the mid 400s and down in the mid 600s. No clue what its over all wavelength would be. I'd imagine that makes figuring its colour temperature even harder.

kien · #7 09-11-2013, 03:15 PM

Quote:

Originally Posted by tang daddy

Fuji apples.....

Fiji purple is 15k same as the Ati purple plus.

That makes sense. It does seem like a 15(ish)K to me.

Aquattro · #8 09-11-2013, 03:21 PM

The closer to white, more growth. More blue, better looking. Find a compromise you like looking at

Coming up with some random number based on averaging different bulbs is at best a WAG. Even bulbs from different manufacturers rated at the same K look different.

kien · #9 09-11-2013, 03:23 PM

Quote:

Originally Posted by Aquattro

Coming up with some random number based on averaging different bulbs is at best a WAG.

but this hobby is all about the numbers man!

Aquattro · #10 09-11-2013, 03:24 PM

Quote:

Originally Posted by kien

but this hobby is all about the numbers man!

True, unfortunately