nd filters let in ir light

[jpandyp]

ive just returned from a trip to scotland , with the clear skies earlier last week i had the good fortune to try a few sunset snowscapes.
the problem i have is that the cokin nd grads are leaving a highly visible cast on the affected portion of the picture.
ive been led to beleive this is ir light that is unaffected by certain filters.
does anyone know of filters that filter out the ir light as well.

i would be most gratefull for any help on this matter

 

[HoppyUK]

Cokins are notorious for that. It's got more to do with the filter not actually being neutral grey than any IR issues. The sensor has an IR filter over it anyway and while IR is a theoretic problem with strong ND filters and some cameras, that's not going to be the case with a 40D.

Lee and Hitech are reckoned to be much better brands.

 

[The Matt]

They will do that unfortunately

I think that for true neutral density you are looking at the likes of Lee filters, which do not come cheap. That's why I've taken to simulating the grad effect by taking two exposures & merging them with a gradient. It's not a perfect solution but until I can afford a set of Lees it'll have to do.

 

[Spiritflier]

Even Cokin Z-Pro filters do it! It can be corrected in ACR and PS but it's a pain in the rear end! I tend to try and work with it rather than against it now.

Try going to the Hue/Saturation tab in ACR and shift the magenta slider about to see if that helps. It should do although it may not remove it entirely but it may give you an effect that you'll like.

Cheers,
Si

 

[Kanine]

Hitech aren't much better. I emailed their CS a while ago to find out if their filters would be resistant to IR, they said no. It's just the nature of the product unfortunately.