ERS Dichroic placement

Beans45601

Active Member
I have never used any solid dichroic filters for straight color before, just crushed glass gobos. When looking around, I see a lot of companies selling dichroic filters that you place in the gel slot of an ERS. Why would anyone buy a larger piece of glass for more money, when you could just drop it into the iris slot? Am I missing something here?
 
While they will not fade, they may shatter from the heat. Some of the ERS's can get very hot at the gate.
 
I've asked before, and don't think I've ever received a satisfactory answer:
Could the light/heat/energy reflected from a dichroic filter back into the lamp/reflector be detrimental?
 
I've asked before, and don't think I've ever received a satisfactory answer:
Could the light/heat/energy reflected from a dichroic filter back into the lamp/reflector be detrimental?

The filters work by phase cancellation. I would suspect that filters in the visible light range are too far out of tune to stop the infrared range and simply let it pass. (The exception being filters that are designed to work in that range, such as used on reflectors.)

The question I always had was more about some of these gobos that only pass a small bit of light (like a star-scape) All that energy being boxed in the lamp/reflector area (especially on old aluminum reflectors) can't be a good thing.
 
Could the light/heat/energy reflected from a dichroic filter back into the lamp/reflector be detrimental?

That was my initial thought. But, it seems like it would be bouncing back regardless of where it was in the instrument. I mean, sure if it was in the gel holder it would have to travel farther to get the reflector, hopefully hitting something else before then.

The filters work by phase cancellation.

I never thought about this too much, but I have always known they worked by cancellation. But, in the few glass filters I have held, I most certainly remember using them to reflect the unwanted light onto a nearby wall...
 

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