Which looses more light: Dichroic or equivalent gel?

[Drcoffee]

If I wanted to convert a blonde (2kw tungsten) to daylight, which would loses more light? a daylight dichroic filter or a full CTB?

Cheers
Jon

 

[10s]

Full CTB = 36% transmission of light, in other words, you're loosing 44% of fixture's light. So a 1k will kick out around what a 350 gives you but with 5600k color temp. The other filter, ...? find the MFG. and look for spec. Gels are relatively inexpensive when compared to good glass filters.

 

[Bucknfl]

I think dichorics will let more light pass thru than full blue gells. Dichorics are expensive and of course can break.

 

[RyanT]

I thought the only difference between gels and dichroics are that the dichroic's don't fade over time. They're just meant to be used on lights where you constantly use them in daylight situations.

 

[KKeller]

I am not sure but it seems to me that the same amount of light should pass through with either filter. There is only so much blue light from a lamp, the filters do not affect that amount, they only filter out the other colors.

 

[sunporchmedia]

The dichroic loses around one stop of light. (a 1k behaves like a 500w) Full blue gel loses about 2 1/3 stops (1k behaves like a 200w). Here's a general rundown on the principle of dichroic filters: http://www.absoluteastronomy.com/topics/Dichroic_filter

If you simply Google "dichroic filter light loss" you can get a lot of information in a flash. Also check out Lowel's website.