On Thu, Nov 13, 2008 at 3:31 PM, John Celio <[EMAIL PROTECTED]> wrote: >> http://www.dpreview.com/lensreviews/pentax_50_1p4_p15/ > > At times it sounds like a sales pitch for the Sigma lens the author > keeps mentioning. > > One thing that confuses me was this text about the distance scale: > "A distance scale is provided with ... a depth of field scale marked for > F11, F16 and F22. As a legacy film lens, this is calibrated for the 35mm > full-frame format, and will therefore be somewhat over-optimistic on > APS-C DSLRs." > > How can DOF be affected by a cropped sensor? The lens itself hasn't > changed at all, just the image-recording surface area. > > John
DoF changes somewhat between formats. Also I've generally found that the acceptable CoC used for DoF marking calculations is rather optimistic for digital use (30 micron CoC's don't play well with 6 micron sensor sites) -- M. Adam Maas http://www.mawz.ca Explorations of the City Around Us. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
