Strangely, my HiTech grads used to give me a strange blue cast, in fairness it was correctable but it would be much nicer to get that sorted in camera. The way I tried to test the cast on the grads was to set a custom white balance without the grad and then take a shot with the grad using that custom white balance. Here is the result from this most unscientific of tests (please excuse the boring shot) clicky
.





