I shoot a bronica sqa, I use a tripod, and shoot 220 velvia 100F. When I do long exposures 2s + I notice that the image is a little fuzzy. It looks ok on the slide, but when I scan it at very high resolution and zoom in a little I see fuzzy images. this happens only to images that have long exposures. Which makes me suspect that I have some camera shake, but I use a solid tripod (gitzo) and solid ball head (manfotto) I just cant figure out what I might have done to produce fuzzy images. May be I should use mirror lock ? Any clue anyone ?