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Weird Lighting Effect/Illusion?

Tony Aroma

Let's Go - Two Smokes!
Veteran
I had an old aquarium light hood sitting around unused, so I thought I might use it for starting seedlings. In the hood are two 24-inch VHO fluorescents, 75 watts each, and two regular fluorescents, 20 watts each. They are a mix of actinic (blue) and white, the mix I used for soft corals. When I plugged it in, one of the 20-watt bulbs was flickering. I don't have any more of the actinic/white 20-watt bulbs, but I did have a few standard 20-watt tubes from Lowes handy. When I put standard bulb in the fixture, I was surprised by what it looks like.

In the picture, the two on the left are VHO "Aquasun," a mix of white and actinic, and on the far right, a 20-watt actinic. Second from the right is a standard fluorescent tube, Sylvania soft white. So why does it look green??? I thought it was an illusion, but as you can see, it clearly has a yellowish-green tint in the photo. I'm not sure why the one Aquasun has a pink tint, but it's the yellowish-green color that seems really odd. I tried another regular florescent bulb, and it too looked exactly the same. Can anybody explain why a soft white bulb looks green in my light hood? I do have another 20-watt actinic, but they seem so much dimmer, I'm not sure which would be best for the plants.

Click image for larger version  Name:	Aquarium Lights.jpg Views:	0 Size:	63.6 KB ID:	18041889
 

GMT

The Tri Guy
Veteran
When you put less watts through an led, it shifts the spectrum to the blue slightly. I'm wondering if the same effect can be seen in a flouro? Slightly orange would become yellowish green if shifted slightly to the bluer end of the spectrum. If so, I imagine your hood is either delivering slightly lower watts than you think or the tube is rated higher.
just a guess, theory.

Or I suppose it could be the very blue tube shining blue light through it. Try removing the far right tube and look again?
 

Koondense

Well-known member
Veteran
The other lamps are high in reds and blue, the regular soft white has more green compared to the others so it looks like she puts out mostly green because the other lights saturate your and camera's vision with blue and red, leaving room for the green to be better seen compared to the blue and red coming from the same lamp.

Cheers
 

waveguide

Active member
Veteran
green is central to our bandwidth and some source attested to it being the colour we perceive as lightest, and perhaps interestingly they went on to say, under low light conditions, human sensitivity then modulates to cyan.

i think it's all very relative, i find corals red/oranges more visually striking (after white golf balls), but it may be by quality of optic sensitivity or receptivity rather than brightness per se. but yes i have occasionally noted that unhued shades do seem green when contrasted sometimes. i guess our shit is nonlinear.
 

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