Dichroic filters instead of CTB at DVinfo.net

Tom Morrow · February 8th, 2013, 08:29 PM

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.

Warren Kawamoto · February 8th, 2013, 09:10 PM

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.

Ken Plotin · February 8th, 2013, 11:43 PM

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

February 8th, 2013, 08:29 PM	#1
Tom Morrow Major Player Join Date: Feb 2011 Location: San Francisco, CA Posts: 416	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.

February 8th, 2013, 09:10 PM	#2
Warren Kawamoto Trustee Join Date: Nov 2006 Location: Honolulu, HI Posts: 1,435	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.

February 8th, 2013, 11:43 PM	#3
Ken Plotin Major Player Join Date: Jan 2004 Location: Los Angeles, CA Posts: 254	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