BTW, Toki 11-16 got some tricky 'hot-spot' problems... i realised it may not be good to use with any DSLR converted with R72. However KT Tan has no problem with it becoz he was using it with his 650nm converted DSLR.
Toki 11-16 tricky 'hot-spot' problems can still be 'manageable' as seen in my shots. Just have to played around with the shutterspeed and aperture in the R72 converted DSLR. And still possible to PP to make 'hot-spot' less obvious.
You know something, SurrealDreamWalker...
Somehow I have a feeling that the filter itself may have (I may be wrong, but it is merely a hunch) something to do with whether a lens gives rise to hotspots or not.
Like you mentioned, if KT1031 doesn't get hotspots with his 650nm, then maybe I still have hope with my Tokina 11-16mm because fatigue is in the process of doing up a 600nm (or 650nm, whichever lah) on a 20D for me...
Let's see how..