Archived posting to the Leica Users Group, 2010/03/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Is the circle really a circle when using ASPH lenses? Sure? Phx Le 19 mars 10 ? 23:34, Mark Rabiner a ?crit : > >> Richard, >> >> The size of a lens image circle is not absolute but depends on your >> criteria. Most lenses are sharp and relatively distortionless in the >> center of the image. Quality and illumination fall off as you move >> away from the axis. You have reached the edge of the lens image >> circle >> when the image quality no longer meets your photographic >> requirements. >> That being said, the easiest way to determine the approximate size of >> the image circle is to hold the lens in front of a ground glass. >> Adjust >> it so that it focuses a distant scene and simply measure the >> illuminated circle on the ground glass. Most normal lenses have a >> reasonable quality of image in a circle with a diameter approximating >> their focal >> length. Symmetrical lens designs tend to have a bigger image circle >> and >> are frequently used for wide angle lenses. >> Larry Z >> > > > And your image circle gets better when you work closer. > That you learn from view camera work. > > [Rabs] > Mark William Rabiner > > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >