ND filters give red hue, normal?

[Will Keir]

I have Tiffen and Schnider ND filters. The more strength, the greater the red hue to the image. I can correct this in RCX, but the skin tones are a bit off.

Is this a common effect of using NDs?

 

[Adam Johnson]

Get yourself a hot mirror and put it in front of your ND filters so you can cut out that nasty IR pollution

 

[Phil Holland]

Many threads and posts on this subject. Here are my thoughts and a test.

The general concept is that the deeper ND filtration you use (darker) the more IR contamination will show up within your shot. It is often gradable, but many Red shooters use NDs with an IR filter in front, IRNDs, or a Hot Mirror/ND combo filter.

Protect yourself before your wreck your shot

 

[Pawel Achtel]

As others mentioned, you need to use IR mirror, like Pancro, for stronger ND filtration. It is not just "red-brownish hue". I found it impossible to colour correct strong IR contamination. But also keep in mind that most lenses do not focus IR on the same image plane as visible spectrum, therefore your images will be also fuzzy.

 

[Will Keir]

Ah, the RED/BROWN hue is IR contamination?

I was using a 1.2 ND with IR. Of the two it was closest to the lens. So put the IR in front so that the light hits it first.

 

[Will Keir]

IR contamination differs with the seasons? I had October sunset skies, shooting directly into the sun.

 

[Will Keir]

Hot Mirror = ND with IR?

Get yourself a hot mirror and put it in front of your ND filters so you can cut out that nasty IR pollution

 

[Pawel Achtel]

IR contamination differs with the seasons? I had October sunset skies, shooting directly into the sun.

IR contamination is usually from surfaces that reflect IR strongest: certain nylons and fabrics, tree leaves, grass.

Yes, different sensor/OPLF combinations will have different sensitivity to IR. My most IR contaminated images were shot on Canon cameras...but this could have been shot specific conditions.

I use Pancro Hot Mirrors and they are brilliant - filtering exactly the same amount of visible spectrum as IR - no colour shifts. I use them routinely with Master Primes.

There are also some special 10-stop screw on ND filters that are much, much better than B+W/Schneider filters. They are "no brand" filters that I came across by accident (don't remember now where I goth them - somewhere on eBay). Not as good as Pancros, but pretty damn good compared to anything else of this magnitude of ND filtration. I haven't used my Hoya or B+W/Schneider 10-stop ND filters since.

 

[Will Keir]

Pawel, thanks for helping out. What do you recommend? Pancro Hot Mirror in 1.2 and a .9?

IR contamination is usually from surfaces that reflect IR strongest: certain nylons and fabrics, tree leaves, grass.

Yes, different sensor/OPLF combinations will have different sensitivity to IR. My most IR contaminatedimages were shot on Canon cameras...but this could have been shot specific conditions.

I use Pancro Hot Mirrors and they are brilliant - filtering exactly the same amount of visible spectrum as IR - no colour shifts. I use them routinely with Master Primes.

There are also some special 10-stop screw on ND filters that are much, much better than B+W/Schneider filters. They are "no brand" filters that I came across by accident (don't remember now where I goth them - somewhere on eBay). Not as good as Pancros, but pretty damn good compared to anything else of this magnitude of ND filtration. I haven't used my Hoya or B+W/Schneider 10-stop ND filters since.