Archived posting to the Leica Users Group, 2010/03/20
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]You are full of mischief mon ami. Cheers Geoff http://www.pbase.com/hoppyman On 21 March 2010 07:41, philippe.amard <philippe.amard at sfr.fr> wrote: > a circle is a circle , how comes it has to be corrected? > > ph > > > Le 20 mars 10 ? 00:35, Geoff Hopkinson a ?crit : > > Yes! It is just a better corrected circle. ;-) >> 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 >> > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >