"Making" white with gels?
- Thread starter FatBird19
- Start date
I don't know if i understand very well what you are trying to do, but if you put red green and blue gel on a single light it's soustractive trichromy so you'll get black, but if you use a blue light, a green light and a red light, this is additive trichromie and you'll get white (in theory). R+G+B=White but R-G-B=black
I think you can do it with only 2 gels, in theory :
White = RGB
Red = G+B stop
Green = R+B stop
Blue = R+G stop
White light + Red gel + Green gel = RGB - (G+B) - (R+B) = 0 (black)
White light + Red gel + Blue gel = RGB - (G+B) - (R+G) = 0 (black)
etc. ...
Try with Cyan Magenta Yellow too
Cyan = B+G = R stop
Magenta = R+B = G stop
Yellow = R+G = B stop
little different with 2 gels :
White light + Cyan gel + Magenta gel = RGB - R - G = Blue light
etc. ...
with 3 gels :
White light + Cyan gel + Magenta gel + Yellow gel = RGB - R - G - B = 0 (black)
N.B. :
The black is not really 'no light' black because of the response of gels. when you look the curve of a Red gel, it never really stops all blue and green frequencies. But be careful, don't use this system to have a N.D. filter. a real ND filter attenuate all the frequencies of the spectre by the same amount. It isn't true with this system !
(I hope you understand me... my english isn't very very good....)
White = RGB
Red = G+B stop
Green = R+B stop
Blue = R+G stop
White light + Red gel + Green gel = RGB - (G+B) - (R+B) = 0 (black)
White light + Red gel + Blue gel = RGB - (G+B) - (R+G) = 0 (black)
etc. ...
Try with Cyan Magenta Yellow too
Cyan = B+G = R stop
Magenta = R+B = G stop
Yellow = R+G = B stop
little different with 2 gels :
White light + Cyan gel + Magenta gel = RGB - R - G = Blue light
etc. ...
with 3 gels :
White light + Cyan gel + Magenta gel + Yellow gel = RGB - R - G - B = 0 (black)
N.B. :
The black is not really 'no light' black because of the response of gels. when you look the curve of a Red gel, it never really stops all blue and green frequencies. But be careful, don't use this system to have a N.D. filter. a real ND filter attenuate all the frequencies of the spectre by the same amount. It isn't true with this system !
(I hope you understand me... my english isn't very very good....)
Last edited:
Guedin said:
White light passing through a Red gel removes Cyan, so you are left with Yellow and Magenta. Next your Green gel will remove the Magenta, so you will be left with Yellow.
Cheers,
Jim
PS: Your English is fine. Just substitute spectrum for spectre. Spectre is more of a ghost.
