What the heck is IR?

[Victor Nhat Nguyen]

I keep hearing about IR when people talk about ND. I know it's some kind of contamination but what is it?

 

[Ryan Patrick O'Hara]

Infrared Radiation.

It's part of the light spectrum we can't see. When we use really high ND filters that do not filter IR light, than suddenly we get a very disproportional amount of IR wavelengths hitting the sensor than regular light. This causes contamination.

 

[Victor Nhat Nguyen]

Infrared Radiation.

Oh okay, so your image will turn purple if you use a bad ND because of IR?

 

[Barry_Green]

It also happens under tungsten lighting. Some sensors are more sensitive to IR than others are. Some cameras will have a problem while others, side by side in the same shoot, won't.

 

[Victor Nhat Nguyen]

It also happens under tungsten lighting. Some sensors are more sensitive to IR than others are. Some cameras will have a problem while others, side by side in the same shoot, won't.

I didn't know that Barry. Is it something to be worried about? wouldn't a simple white balance do the trick?

 

[Barry_Green]

No, white balancing doesn't fix it. And it only manifests itself on certain dark objects, not all. Black synthetic fabrics are more likely to show the effects of IR contamination than natural fabrics, for example.

If you are encountering IR pollution in your footage, the only fix is to filter out the IR using an IR-cut filter.