Bad form to reply to oneself, but since I'm mostly talking to myself here I pass this along just to be complete. : ) I found the following illustration of how sensors were always discussed pre-Exmor. A lot of people still discuss them this way, throwing them all in the same "bucket". http://www.antiqueauto.org/assets/\Non-Exmor-Deep-Well.png But imagine if the photo-receptors at the bottom of those wells was moved up and put directly behind the microlenses. Now what do you get for off-axis light performance? I think it appears to be a no-brainer that it would be improved but I have yet to see it quantified or talked about. Why?
Pentax (and other manufacturers) aren't going to come out and say "Hey, those 'optimized for digital" lenses we sell? You don't really *need* that optimization for the cameras using the Sony Exmor. You can get great performance with the old lenses made for 35mm film!" That doesn't help them sell today's lenses. They'd rather have you hear "optimized for digital" and not think about what the MEANS. Tangentally, I think this may also explain why Sony NEX/Exmore users are at the forefront of going ga-ga over using all manor of legacy film camera lenses on their NEX. (First, due to the flange to sensor distance, all they need is an appropriate adapter to fit the mount of just about ANY 35mm film camera. Secondly, the Exmor sensor performs just stunningly with their off-axis performance. Thirdly, the APS-C sensor only uses the central part of that image disk, cutting off the extreme off-axis that you would have seen in the corners of a full 35mm frame.) On Mon, Sep 24, 2012 at 2:30 PM, Darren Addy <[email protected]> wrote: > On Mon, Sep 24, 2012 at 1:47 PM, Bruce Walker <[email protected]> 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... -- "The key to seeing the world's soul, and in the process wakening one's own, is to get over the confusion by which we think that fact is real and imagination an illusion. It is the other way around." -Thomas Moore, "Original Self" -- 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.
