Solution to IR Pollution - IR ND FIlter Tests

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8 years ago
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More info: http://tomantosfilms.com/13965/solution-to-ir-pollution/
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Here are the filters I used in the test:

Cavision Filters:
Hot Mirror Filter - https://goo.gl/abRMnT
Graduated ND 0.6 - https://goo.gl/tcF8cn
0.9 ND - https://goo.gl/P7wtBX
1.5 ND - https://goo.gl/i9JgvT

Tiffen Filters:
T1 IR Filter
Full Spectrum IRND 0.3 - https://goo.gl/UDsXsL
Full Spectrum IRND 0.6 - https://goo.gl/fkcYrW
Full Spectrum IRND 0.9 - https://goo.gl/SJmgCw
Full Spectrum IRND 1.2 - https://goo.gl/7m00NK
Full Spectrum IRND 1.5 - https://goo.gl/8eSyyn

I already talked about how IR (infrared light) pollution can be a problem on some cameras. Mostly with the new cinema cameras such as the URSA cameras from Blackmagic. Both the Minis and the full size URSA don't have any internal filters that will cut out infrared light. If you are wondering if your camera can suffer from that problem then just check if it doesn't already have a low-pass filter. Most cameras with low-pass filters built in also have a IR element built in. But if your camera doesn't have or come with exchangeable low-pass filters then there is a good chance that IR pollution could cause you some headaches. In the end the best way to find out is to test out your camera.

To see if your camera suffers from IR pollution just shoot a test shot without any filters and then the same shot with strong ND filters. If you see a significant shift in colors towards reds; specially in the shadows. Then that means your camera has IR pollution problem. This will usually be visible only when using ND filters because ND essentially block out the visible light spectrum. The light that me and you can see. But camera sensors can actually see more light then we can. It can see into the wavelengths of light known as infrared. Since this light is on the warmer side of the light spectrum it means that if you block out all the visible light with an ND filter BUT not the infrared light, then this light will turn your whole image a lot more red. So to fix that you need to either get different ND filters that will block out not just the visible light spectrum but also the infrared light. These filters are commonly known as IRND filters. Also you can get a clear filter that will just stop the infrared light and put that in-front of your lens together with a standard ND filter. In my tests you can see me test out both approaches to this problem. Hope you guys find these tests useful.

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My name is Tom Antos. I am a film director and cinematographer with over 15 years experience in VFX & animation.
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