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Old February 8th, 2013, 08:29 PM   #1
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Dichroic filters instead of CTB

I've never really heard of anyone using Dichroic filters before, but I've been noticing that Lowel makes them for all the fixtures I own. The idea is that a Dichroic filter is a piece of glass with a thin film that changes the color of light using interference. The one that Lowel makes replaces a CTB gel, converting tungsten to 5500k.

The advantages I can see are:

- Perhaps easier and quicker to deal with than gels
- Perhaps might reflect heat away from front, making other gels (e.g. diffusion) cooler.
-This is the cool thing: absorbs less light than a CTB gel because it's using a different physical principal. Rated one stop loss for the dichroic versus approx 2 stops for the CTB.

Just curious if others have tried them. The downside is that they seem expensive, almost as much as the lights themselves. But if you get twice as much light from a fixture that's worth something.
Tom Morrow is offline   Reply With Quote
Old February 8th, 2013, 09:10 PM   #2
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Re: Dichroic filters instead of CTB

Dichroics are heavy and expensive, and needs a lot of tender care. One drop and it's done. Same when you pack them, you can't pile stuff on it or they'll break. Think eggshells.
Warren Kawamoto is offline   Reply With Quote
Old February 8th, 2013, 11:43 PM   #3
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Re: Dichroic filters instead of CTB

Also, dichroics do fade over time...the coating is affected by the intense heat, and the color temp shifts to the red end. My old dichroics for the Mickey Mole were 4800-4900K after about a year. Still usable, but definitely needed a 1/2 booster blue (Rosco) to get them back in range.

Ken
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