This is regarding lenses meant for film/FX/full-frame but used on an APS-C/DX sensor. Since there is a 1.5x (or 1.6x) crop factor on these cameras, only the center 2/3 (or 5/8) of the actual front diameter is used. This means that using a step-down ring, I should be able to use a 52mm filter on a lens with a 78mm front thread for 1.5x (77mm std. filter size), or 83mm front thread for 1.6x (82mm std. filter size)... right?
PS: Yes, I know the added thickness of the step-down ring may cut down on the usable front thread size for a certain filter, especially for wide-angles... so maybe not quite 52-on-77, but 52-on-72 for telephotos, 52-on-67 for normals, and 52-on-62 for wide angles?
PPS: I also know I should've just bought gigantic 77mm (or larger) filters and gotten step-up rings. I was an idiot. But I don't wanna spend money right now, so if I can do it this way, maybe I'll get another $30 lens ;)
Message edited by author 2010-04-20 07:38:11. |
