Infra - red again

[Brian D. Goff]

Just had a job were we shot an infra - red heating device. The heaters turned out all magenta. The guy with the canon still camera got nice red heaters

If I had used a hot mirror - would that have helped?

 

[Mitch Gross]

Correct.

 

[Nils Ruinet]

I was shooting in a studio yesterday, just black / white backgrounds, not really powerfull sources (1KW, 2 KW), but I noticed some purple shifts in the black clothes, so I tried to use my IR (Formatt) filter, and I saw a major improvement...
I've also noticed that it helped when shooting greenscreen...

I guess I'll be using it much more often from now on...

 

[Mike N]

I'm sorry but I always wanted to understand why is it that these problems with infrared light comes from black objects ? If the black object is cold would it also pose a problem ?

thanks

 

[Charles Angus]

Objects that reflect little visible light do not necessarily reflect little of the wavelengths we can't see (like far red and infra red). So, the answer is - if we could see a broader range of colours, the black objects wouldn't look black.

Because there is little visible light compared to infra-red, the infra-red is a bigger problem.

 

[Dan Hudgins]

IR and focus

IR and focus

Its not just the color shift issue, most lenses will not focus IR at the same point as green, so if you use an IR/UV filter you can get sharper results since the off color halo around the points will be filtered out. I would use and IR/UV or XB29 filter on all shots, if you need wide angle then switch from IR mirror to IR absorbing glass.

 

[Raphael Varandas]

Hey Guys look this article... is very nice

http://provideocoalition.com/index.php/aadams/story/red_hot_mirror_shoot_out/


About hot mirror and IR in RED

 

[JanneJansson]

We had a daylight shooting yesterday and black clothes looked purple.
I don't understand, REDONE have a IR-filer over the sensor ..or?

 

[Brook Willard]

We had a daylight shooting yesterday and black clothes looked purple.
I don't understand, REDONE have a IR-filer over the sensor ..or?

It does have an IR filter, it's just not strong enough. Manufacturing IR filters is difficult... if it's too strong, they'll cause a sort of vignetting on wider lenses. If they're too weak, well...