Bruce Walker wrote: >On Mon, Sep 24, 2012 at 3:16 PM, Mark Roberts ><postmas...@robertstech.com> wrote: >> Bruce Walker <bruce.wal...@gmail.com> wrote: >> >>>Pentax literature points out how the final element of DA glass is >>>configured to direct the photons at right angles to the sensor to >>>compensate for the fact that the sensor is most sensitive to >>>perpendicular light. Film did not have this issue, hence FA glass (and >>>before) doesn't do this so the image will be fuzzier, especially off >>>center. >>> >>>My understanding is that all DA glass has been created with this >>>astigmatism compensation specifically with sensors in mind. >> >> Erm, this is nothing to do with astigmatism. > >Okay. It might have more to do with the marketing hype as someone >mentioned, as I scraped that off of the current Pentax.jp site wrt one >of the DA lenses. :-)
It's probably a mistranslation, then. Astigmatism is a lens aberration in which light rays are bent differently along the horizontal axis with respect to the vertical. Or vice-versa ;-) -- Mark Roberts - Photography & Multimedia www.robertstech.com -- 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.
