Red One IR filter

[Jon Chema]

I mainly shoot RED MX but I'm doing a shoot with an older Red Mysterium and was wondering about using an IR filter. I've heard a bunch of things but from what I understand an IR filter (Hot mirror) should be used on the older sensor. Does anyone know anything about this? I'll be shooting outside and using ND, Pola, and grads if that makes a difference.

 

[Jake Bastian]

Any ND over .6 should be used with an IR filter on the RED to prevent IR pollution in your image. There is some debate over whether to use and IR filter or a hot mirror filter - the IR filter has a tint designed to counteract IR pollution, while the hot mirror filter is designed to prevent IR waves from ever hitting the sensor in the first place. I personally use a hot mirror filter.
If you have the budget you should try and get ND/hotmirror combo filters to limit the amount of glass you're stacking in front of your lens.

 

[Eirik Tyrihjel]

The amount of IR radiation varies enourmosly, it´s like the weather - sometimes you get a lot, sometimes almost nothing at all. (But IR you can´t see, so you never know...)
From what I understand heat increases the chances of high amounts of IR.
IR is part of the spectrum emitted by the sun, so in theory it doesn´t happen at night, but I believe certain light sorces also emit IR.
When you start adding ND filters you stop down the amount of light that hits the sensor, while the IR goes though your NDs like the were never even there. So by adding a lot of NDs in a high-IR environment you will increase the ratio between IR and real light allowing the IR to pollute your scene.
In the worst case we ever had (ND 2.1) the green color in the grass was just totally gone - the green grass was GREY! The next day ND 2.1 and no IR did nothing, grass was perfectly green.

If your blacks go purple or green goes gray, or funny stuff happens to your colors in general while you are stacking ND´s chances are its IR that is causing it and a hot mirror / IR filter should be stacked in front of the filters with the most mirror-like side facing outwards (away from camera).

Apparantly R1 MX is a lot less exposed to this than the origina Mysterium.

 

[Jon Chema]

The amount of IR radiation varies enourmosly, it´s like the weather - sometimes you get a lot, sometimes almost nothing at all. (But IR you can´t see, so you never know...)
From what I understand heat increases the chances of high amounts of IR.
IR is part of the spectrum emitted by the sun, so in theory it doesn´t happen at night, but I believe certain light sorces also emit IR.
When you start adding ND filters you stop down the amount of light that hits the sensor, while the IR goes though your NDs like the were never even there. So by adding a lot of NDs in a high-IR environment you will increase the ratio between IR and real light allowing the IR to pollute your scene.
In the worst case we ever had (ND 2.1) the green color in the grass was just totally gone - the green grass was GREY! The next day ND 2.1 and no IR did nothing, grass was perfectly green.

If your blacks go purple or green goes gray, or funny stuff happens to your colors in general while you are stacking ND´s chances are its IR that is causing it and a hot mirror / IR filter should be stacked in front of the filters with the most mirror-like side facing outwards (away from camera).

Apparantly R1 MX is a lot less exposed to this than the origina Mysterium.

Makes sense. I knew that the older R1 had issues I just wasn't sure the scenario that the IR came about.

 

[Alexander Chinnici]

I am also shooting on the older Red (now I'm use to the MX!) but the entire shoot is under tungsten light. I was also thinking of making the lights even warmer...

Is it foolish to use an IR filter under these circumstances?

 

[jbeale]

filtered tungsten light = more IR

filtered tungsten light = more IR

tungsten lights put out quite a bit more IR light than visible light. The IR/visible ratio goes up even more when you add filters, because most gels are nearly transparent in the IR even if they are quite dark in the visible. So a heavily filtered tungsten source may be a good candidate for an IR problem.

However this is all just theory- the only way to be sure is try it with, and without the IR-block filter (eg. hot mirror) and see if there is a color shift. Some black synthetic fabrics show the problem most easily because they are black in visible only, and quite reflective in near-IR. If you have a problem you'll see such a fabric start to look purple in the camera.