ND Filters & Infrared Pollution on Canon DSLR's

[Rob Davis]

I want to purchase a set of high-quality 4x4 ND Filters for use with the Canon 5D Mark II and 7D cameras as well as the GH2 when shooting bright exteriors. I will probably start with two filters that I can use independently or stack together for three total possibilities in f-stop reduction and build from there.

 

I understand that when you add a lot of ND glass in front of the lens you can get a color cast from the infrared light, which the ND's don't block like they do visible light. Some people seem to advocate compensating for this with either IRND's such as Tiffen's white water filters or by stacking an IR/Hot Mirror filter in front of the ND's while others claim that the Canon DSLR's have sufficient ability to compensate for IR pollution in-camera and standard ND's are fine even when going down 8 or 9 stops.

 

Can anyone comment on the need for IR filtration when using a lot of ND on these cameras? On a side note, if you were shooting bright exteriors and could only bring two ND's, which would be the first two you would grab? I'm thinking about getting a ND.9 and a ND.1.8, which would give me 3, 6 or 9 stops of light reduction.

[Rob Davis]

If anyone else is interested in this, I found this post at DVXuser that seems to suggest that at least the 7D lacks sufficient ability to deal with infrared in-camera when using lots of ND: http://www.dvxuser.com/V6/showthread.php?188656-Is-this-IR-pollution . Would love a conclusive answer about this though and still can't speak to the 5D and GH2.

 

Still not sure whether to go with standard ND's with hot mirror or IRND's. Any suggestions?