Does anybody know what the lens tilt offset is for a 150mm lens that is on a vie w camera focused at infinity and sits 5.5 ft off of the ground? (I'm referring t o the offset in the image circle) This is for landscape and the lens is downtilt ed. Also will the focus shift on distant objects when the lens tilt is varied ev en though the lens is focused at infinity? What are the advantages and disadvant ages of having a leather bellows instead of a synthetic one? Which is better?