Maybe Pentax just uses slower lenses (they do) and doesn't correct (no idea since the data wasn't there). The funny thing would be if they didn't correct there would no evidence of it in this data but rather in inconsistent exposure results between lenses.
On Wed, Nov 3, 2010 at 10:43 AM, CheekyGeek <[email protected]> wrote: > On Wed, Nov 3, 2010 at 8:58 AM, Dario Bonazza <[email protected]> > wrote: >> This is rather interesting to me: >> http://www.luminous-landscape.com/essays/an_open_letter_to_the_major_camera_manufacturers.shtml > > Dario, > Thanks for sharing this link. I learned A LOT of things I didn't know. > I would love to see a siimilar Dx0 chart for Pentax sensors. A few > random thoughts after reading the article: > > 1) I always wondered about the differences between using FA and DA > lenses on a Pentax DSLR. Besides illuminating a smaller circle, it > would seem that lenses "designed for digital APS-C sensors" might be > designed to provide a more parallel light path between the rear > element and the sensor than traditional full frame lenses. > 2) This might explain why an old, slow lens like the Tele-Takumar > 200mm f5.6 (with it's 49mm filter size) gives such GREAT results on a > DSLR. > 3) Either the light loss at the sensor or the difference between > T-Stop and F-Stop for their particular lens would seem to explain why > some shooters complain of exposure problems with some lenses. Perhaps > their cameras are NOT designed to cheat the ISO, as the others are. > 4) I'm a little unclear on how this issue relates to sensor size. My > first thought is that a larger sensor would reduce this problem, (and > therefore be another technical reason that a full frame sensor camera > would be superior to a APS-C camera) but I'm not sure if that is > correct. > > I don't see manufacturers changing their ISO cheating ways. What I'm > not clear on is whether the EXIF ISO shows the one you had set on the > camera or the real (cheat) ISO - and if that "standard" is the same > across all manufacturers. > > Darren Addy > Kearney, Nebraska > > -- > Nothing is sure, except Death and Pentaxes. > > -- > 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. > -- Steve Desjardins -- 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.
