Hot Mirror versus IR Cut filters

Ryan Patrick O'Hara

Ryan Patrick O'Hara

Veteran
What is the difference?

I'm purchasing some tags for my mattebox and I have the option of Hot Mirror and IR Cut. I've used both but sadly don't know the technical difference between the two. They both cut IR wavelengths, but why do they have different names?

I'm leaning toward the IR CUT because it's much shorter of a tag versus HOT MIRROR.
 
They mean the same thing. Hot Mirror is just the colloquial term for IR Cut filter and Cold Mirror is the colloquial term for IR Transmission filter. Its like getting a Don means the same thing as getting one for safety.
 
technically the result must be the same, but they are different ways of reaching the goal.

mirrors are... mirrors, so they reflect the unwanted wavelength. The is the most efficient way to do but has some drawback, the main is you must have the mirror has first element, because else, the reflected energy can be trapped (between two lenses for exemple) and create problems. The advantage is you can reflect huge energy (very useful in laser physic experiment )
the other way (what most photographic filters do) is to add a pigment in to glass or plastic, that will either absorb or change the desired wavelenght. this kind of filter is ok for low energy since they are supposed to "heat" as long as they are absorbing energy.
Depending the way mirrors and filters are designed, they can also offer more or less bandwith.
Mirrors are piece of glass with a thin layer of evaporated metal, and are very sensitive to fingerprints and dust and difficult to clean.
Filters are usually colored in the plastic, but sometime only on the surface, so they should be more tolerant to wear, but not for sure.
 
Very informative. I guess I'm just going with IR Cut. These are just the velcro tags an AC puts on the side of a mattebox to show what is in the filter trays and help remind the DP/OP/or himself what is in.... (so you don't forget to take out an ND or 85!)
 
Great information. I looked this up a long time ago and even wikipedia didn't explain it this well. I'd been told for so long they were the same thing. Makes sense though.
 
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