Banding in IR photos

More tryout with IR photos, and I find that the K20D is not very suitable for this purpose. The huge 16-stop exposure compensation is one reason (and that's because the strong IR-cut filter in front of the CMOS); but the main problem is random banding appears on the picture.

The banding in the following image is not the worse one. At worst, the whole picture is not visible. However, the picture sometimes appears clean without banding..... Since it appears randomly, you cannot avoid it.

Also try the IR filter on my friend's istDs, banding is still there, but not that serious. The exposure compensation factor with IR filter for istDs is 13-stops, much better than on K20D. Maybe I should test my istD with IR.....