Archived posting to the Leica Users Group, 1999/09/20
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]In a message dated 9/20/99 2:04:56 PM Eastern Daylight Time, chris@almqvist.net writes: << Sorry, this is not a reply, but rather a request for clarification: If I look at the camera lens thru the filter, and then tilt the camera away from me so that the inside of the lens partly disappears, but not because it is covered by the filter but because it is covered by the outermost rings of the lens, then to my mind there is no vignetting caused by the filter. Right or wrong? And if there is a bit of vignetting caused by the filter when the lens is fully opended, will the vignetting disappear if I close the lens down a few stops? >> The way I check for physical vignetting is by pointing the lens toward an even light source (like a white wall) so all 4 corners of the finder are brightly-lit, stop the lens down to the smallest aperture and press the DOF preview. The vignetting effects of a filter or lens hood always appear more pronounced in the finder at smaller stops than wide open. With some lens-hood-filter combinations the vignetting as not even visible at all until the smallest aperture. I also check at both minimum focusing distance and infinity. Some lenses will show filter/hood vignetting at one but not the other. In addition, wide zooms (not an issue with Leica) need to be checked throughout the focal length range. With the M Leica you either need to shoot a test film, or place a ground glass at the film plane. With the R Leicas I would advise the same, because their finders do not show 100%. I have many lenses which I've checked on my Nikon F-series bodies (100% finders) and found them to vignette whereas they look perfectly fine on FM2n or n90s which have 93% and 92% finders (respectively) which are close to the R's finders.