----- Original Message ----- From: "Peter Spiro" <[EMAIL PROTECTED]> > The published resolution tests are not very useful for wide angle lenses. > These tend to have more field curvature, and their close distance > performance is not good in the corners for flat objects, such as the test > targets in resolution tests (which are at less than 2 meters distance from > the camera). Thus, the 35mm f/2 has a low resolution rating in the corner > in the resolution tests. However, my real world tests for subjects at > infinity shows that its corner performance is if anything better than the > 50mm lenses, which score higher in the resolution tests. > > These tests can be found linked to my home page at > http://ca.geocities.com/spirope/photopage.htm > Why should lens manufacturers be excused for letting so much curvature of field occur that corner resolution at close distances and large apertures is compromised? Besides, 1-2 metres is not such a small distance for a WA lens. A lens would be damned for any other optical defect, so why not for this? Field flatness at all distances is a worthwhile goal for any lens to achieve. Anyway, is there some convention that prevents a lens from being focussed in the corners when corner resolution is being tested? Was there a desire to only use one frame of film at each aperture being checked? Regards, Anthony Farr - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
