On Mon, Sep 24, 2012 at 1:47 PM, 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.
Yes, that is true Bruce but we must remember there are traditional sensors and then there are the Sony Exmor sensors used in the K-x and the K-5 (and presumably other models). Take a look at the fundamental design change that the Exmor brought to the table, especially as it affects off-axis light sensitivity: http://www.antiqueauto.org/assets/ExmorSensorAdvantage.png Instead of the light entering the microlens and travelling down a virtual "pipe" before it gets to the photo diode, the microlens sits directly ON the photodiode. What gets talked about all of the time is how many more photons this captures (and so better performance in the same low light when compared to other sensors) but what I don't see get directly talked about is the obvious off-axis light performance. Many Pentax lenses were designed as you say (and would thus work well on either the old style or Exmor sensors. But I believe that the performance of lenses made for film cameras (and the F and FA lenses) would be significantly better on the Exmor sensored cameras than they were on pre-Exmor sensored cameras. I just can't find a lot of people that directly speak to this issue. Maybe a question for Falk Lumo to consider, if he hasn't somewhere already... -- 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.
