I have a B+W 4.0 ND filter and IR contamination is a problem with this and other filters. One of our members, Graham from OR, recommended using the new Tiffen ND filter line as it has an IR cut filtration built in. I really did not want to add more ND to an already dense filter and I did not want to buy two new Tiffen filters to get the ND of 4.0.
I did research on the new Tiffen IRND filters and found they had a slight green cast. During my search I came across the Tiffen T1 IR cut filter which also had a slight green appearance. This filter seems to be a favorite of videographers, especially for use with certain Sony cameras that have a strong near IR response. I figured the green cast in the Tiffen IRND filters was probably related to how this filter worked and I should be able to simply put it in front of my b+W. At about $78 dollars for a 77mm filter, it seemed worth a shot.
I did a quick and dirty test today. Here is the original scene. No processing and straight out of the camera:
Here is the exposure with only the B+W 110 4.0 ND filter straight from the camera:
Here is the B+W filter plus the Tiffen T1 IR cut filter straight from the camera:
Correcting the color in post can get the B+W filter closer. With just rocks and water, it is easier than water and trees, but is a simple processed image using white balance in ACR and a quick fix to contrast:
Here is the corrected shot that used the Tiffen T1 filter:
To me, the Tiffen T1 filter really helps IR contamination when using strong ND filtration, especially B+W filters. It is much easier to get natural color out of an image. It also seems to be an inexpensive solution. I believe the filters come not only in round, but also square.