Archived posting to the Leica Users Group, 2010/03/20
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Le 20 mars 10 ? 00:35, Geoff Hopkinson a ?crit : > Yes! It is just a better corrected circle. ;-) do you mean to say it is ACircular? ph > FWIW all of the M lenses produce an image circle sufficient to cover > all of > the 24x36 mm rectangle and Peter Karbe (Optics department head at > Solms) > recently said that the S system lenses provide an image circle > sufficient > for that camera's 30x45 mm sensor (but no larger) > > Cheers > Geoff > http://www.pbase.com/hoppyman > > > On 20 March 2010 08:40, philippe.amard <philippe.amard at sfr.fr> wrote: > >> 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 >>> >>> >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information