I am using the slim filter from Heliopan which is the thinnest one they have available and specially made for wide angle lenses. My reasoning behind the coating question was based on the assumption that the more light gets reflected off the surface of the filter, the less light will be available to pass through. This compounded by the curvature of the lens towards the edges could create a significant reduction of light on the borders of the image. No ? The only filter I have seen that is slimmer than the one I am using is the B+W. However, there is a price to be paid. B+W slim filters are so thin that they don't have threads on the outside thus preventing a lens cap from being placed in front of the lens. I am going to run some tests as Laurenz suggested and see what the difference is. I have always been skeptical about using lenses (specially the more expensive ones) without a filter as protection. But in this particular case I just might have to open an exception. Joseph --- Dr. Joseph Chamberlain Oral and Maxillofacial Surgery ---------------------------------------------------------------------------- On 11/15/05 10:01 AM, "Gregory Fraser" <Gregory.Fraser@xxxxxxxxxxx> wrote: > >>> My impression is that this is being cause (at least in >> part) by the filter I >>> am using. When I purchase my camera I asked for Heliopan >> multicoated UV >>> filters for both lenses. > > Seriously speaking, would cheaper coating cause vignetting? If so then > wouldn't no coating at all (or no filter) cause even more vignetting? > > Are you using the slim or super-slim filters designed for wide angle lenses or > are you using the regular, thicker filters? > > Greg
