lights and color temp.

whaase · #1 01-29-2004, 10:14 PM

I've been wondering this for awhile and now I'll ask

I'm not understanding how a flourescent bulb that is 6500k is fairly blue. Yet a 10k MH bulb in ice white. Or actinic bulbs are 7100k and a 10k is white. Anyone care to teach me?

Walter

Bob I · #2 01-30-2004, 01:29 AM

Quote:

Originally Posted by whaase

I've been wondering this for awhile and now I'll ask

I'm not understanding how a flourescent bulb that is 6500k is fairly blue. Yet a 10k MH bulb in ice white. Or actinic bulbs are 7100k and a 10k is white. Anyone care to teach me?

Walter

Well to begin with at is a FLUOrescent tube, and a 6500K fluorescent will not be blue or even close to it. Actinic bulbs are not 7100K. Anyhoo the way I understand color temp is related to burning of metals. That does not help, but the higher the temp of a bulb the more blue it will be until it becomes purple, and then black.

StirCrazy · #3 01-30-2004, 01:42 AM

Quote:

Originally Posted by whaase

I've been wondering this for awhile and now I'll ask

I'm not understanding how a flourescent bulb that is 6500k is fairly blue. Yet a 10k MH bulb in ice white. Or actinic bulbs are 7100k and a 10k is white. Anyone care to teach me?

Walter

ok a 6500 tube is not blue in anyways it is yellowish white (more to the white side)

the 7100 blue bulbs you were talking about were 7100 color rated bulbs with blue phosphers to make the light look blue, but there is no actinic light to them.

10K is white.

these are all based of the ansi standerd that compars them to the color a black body will radiate when it is heated to a specific temp. so the 6500K is actual a tempature that relates to a color, but only if the company follows the ansi standard. Sylvainia just brought out a "daylight compact floressent" that has a actual color temp of 3200K.

so for a referance the afternoon sun at the equator is 6500K so that means it emits the same overall color as a black body heated up to 6500Kelvin if you go higher there is more of a blue componant added to the light so it appears whiter and then after a certian point it starts taking on a blue hue, then vilote (sorry Bob no such thing a purple light

)

so a 10K bulb should be realy white and a 15K bulb should be white with a touch of blue, 20K should be a nice blue and so on.

here is a neet link to help understand
http://cs.clark.edu/~mac/physlets/Bl.../blackbody.htm

Steve

whaase · #4 01-30-2004, 02:06 AM

That helped quite a bit. But, when I had my FW tank and I have a 5500k bulb it looked very white, then I added 6500 Daylight Delux tubes, they were very blue compared to the 5500k. Thats why I though a 10k should have been even more blue. (If that makes sense)

Thanks for the info guys! I still can't believe Bob corrected my spelling!

Walter

StirCrazy · #5 01-30-2004, 02:10 AM

Quote:

Originally Posted by whaase

I still can't believe Bob corrected my spelling!

Walter

get used to it

Steve

whaase · #6 01-30-2004, 02:14 AM

Just to clarify where I got the 7100k as a actinic. In my MOPS cat. Coralife advertises the following. "The Actinic 03 Blue 7100k lamp is 100% blue actinic that peaks at 420 nanometers". Is it right? Or could they take any color temp and isolate it at 420 nanometers? I guess it really doesn't matter

Just curious...

Walter

StirCrazy · #7 01-30-2004, 02:55 AM

the 7100 has the same color of actinic but it is not a true actinic light. if you don't have to go PC for actinic then don't it is easyer to buy a URI super actinic.

Steve

Bob I · #8 01-30-2004, 02:57 AM

Now I hope someone will explain this 03 thing.

BCOrchidGuy · #9 01-30-2004, 02:59 AM

Walter, color temperature is simple. If you take a carbon block and apply heat eventually it will glow. When it glows at a certain temperature it's rated at that colour temperature. IE if you heat it up it will go from deep red to red, to orange to yellow and eventually to white and then onto blue. When a bulb says it's a 6500k bulb that's supposed to be what colour the Carbon block would be glowing at that 6500 degrees Kelvin or 6226 degrees Celcius. A 10,000k bulb would give a colour off similar to the carbon block when it's at 10,000 kelvin or 9726 Celcius.
One more thing to help understand the colours is, noon day sunlight at the equator will be between 5000k-6500k depending on the season.

When you get into actinic, you're not talking about a white light so the colour temperature is not applicable, it's a mono chromatic colour, so it's rated at it's peaks.. which should be 430-430nM for actinic.

Doug

whaase · #10 01-30-2004, 03:00 AM

Quote:

Originally Posted by StirCrazy

the 7100 has the same color of actinic but it is not a true actinic light. if you don't have to go PC for actinic then don't it is easyer to buy a URI super actinic.

Steve

Now you just confused me again!

If 7100k is the same visable color as actinic, and actinic is very blue, then how can 10k be white?

Walter