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Dichroic Filters Versus CTB


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#1 M Joel W

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Posted 13 March 2007 - 06:18 PM

Why would I buy this?

http://www.bhphotovi...oughType=search

Why I could buy a sheet of CTB for five bucks? Is it more efficient or something? Or is it just more firmly secured?
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#2 Michael Nash

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Posted 13 March 2007 - 06:21 PM

It's more heat resistant when used on small lights, and fits inside the barn doors. Gel that close melts in no time.
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#3 Walter Graff

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Posted 13 March 2007 - 07:36 PM

If you got glasses, you could get nicely coated glass lenses or if you were a rough and tough guy who broke your glasses a lot and didn't mind them not being optically perfect you could get cheaper polycarbonate lenses. Okay, bad example. Dichroics are accurate color changers that like the last poster pointed out can take the heat. They also don't get hot when in front of the source of light due to how they filter light. That said, you could use a CTB and basically do the same thing, or at least no one would notice. No you can't put CTB in a gel holder directly in front of a light but a full sheet fits easily on the doors of a 1k with no problem. And for $143 a peice of glass breaks (dichroics seem to break easily for some reason) so for $5 you'd be better off with gel. Dichroics also relfect infrared heat back so teh light they prodice seems cooler, but they also make your fixtures hotter as a result.
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#4 M Joel W

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Posted 13 March 2007 - 08:13 PM

If you got glasses, you could get nicely coated glass lenses or if you were a rough and tough guy who broke your glasses a lot and didn't mind them not being optically perfect you could get cheaper polycarbonate lenses. Okay, bad example. Dichroics are accurate color changers that like the last poster pointed out can take the heat. They also don't get hot when in front of the source of light due to how they filter light. That said, you could use a CTB and basically do the same thing, or at least no one would notice. No you can't put CTB in a gel holder directly in front of a light but a full sheet fits easily on the doors of a 1k with no problem. And for $143 a peice of glass breaks (dichroics seem to break easily for some reason) so for $5 you'd be better off with gel. Dichroics also relfect infrared heat back so teh light they prodice seems cooler, but they also make your fixtures hotter as a result.


Wow, great stuff! Thanks for the comprehensive reply. Since dichroic filters look "magical" I kind of assumed they might be more efficient.
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#5 Brian Drysdale

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Posted 13 March 2007 - 08:24 PM

Wow, great stuff! Thanks for the comprehensive reply. Since dichroic filters look "magical" I kind of assumed they might be more efficient.


It's worth getting different grades of CTB - 1/2, & 1/4 as well as the full. Clipped onto the barndoors the gels last a reasonable time, however, you do need to check for discolouration & fading.

I've only used dichrioc filters on battery lights, never on the larger lights. Although one advantage is that you don't get wind noise when being used outdoors.
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