On Wed, Apr 6, 2011 at 10:12 AM, Mark Roberts <m...@robertstech.com> wrote:
> If you had a lens that was perfect in every regard *except* spherical > aberration and aimed it at a concave surface (of precisely the right > curvature) everything would be sharp. You fell for Steve's cunning trap, and are also confusing spherical aberration and field curvature. :-) In the presence of spherical aberration, there's no way to bring even a single point to sharp focus, let alone a surface (whether planar or curved). See the ray diagrams at: http://en.wikipedia.org/wiki/Spherical_aberration You can see why stopping down the aperture mitigates spherical aberration; the rays at the edge of the aperture come to a different focus than those near the center. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
