I've sent a follow-up question to Falk Lumo, because it appears that my original point is still valid, even if the Exmor (APS-C) is not backlit or the same as the Exmor-R technology. The deep well is still shallower (and the photo diodes are bigger). Here is my most recent question of him: - - -
Thank you for your reply to my question and correcting my misperception/confusion regarding the Exmor (APS-C) vs the Exmor-R sensor. I would like to follow-up my question with some corrected data then. Here is an image from the Sony page for the Exmor (APS-C) ( http://www.sony.net/SonyInfo/technology/technology/theme/cmos_01.html ) http://www.antiqueauto.org/assets/ExmorAPS-C.png It appears that my original point is still valid. By shortening the length of the "deep well" (as well as using physically larger photo diodes) it appears that more off-axis light reaches each pixel than in the previous sensor designs. I have never seen this addressed in experiment or comparison however. The manufacturers are not going to make a big deal about it, because they want you to think that you must have their "digitally optimized" lenses. But if one of the improvements that come along with the Sony Exmor (APS-C) sensor is better performance with off-axis light, then it means that a user with "legacy lenses" designed for film will see an improvement in the performance of those lenses simply by putting them on a camera with an Exmor (APS-C) sensor. I believe that this should be seen especially easily when it comes to "purple fringing" which (as I'm sure you understand much better than I) is a result of light bleeding into neighboring pixels and often worst with fast film lenses. I think it would be interesting to test (for example) two lenses that are as close as possible in specs and have them shoot the same purple fringe inducing scene on BOTH an Exmor sensor and a non-Exmor sensor (say the K-7 vs the K-5). Candidates for comparison might include the Pentax-A 50mm f1.7 vs the DA 50mm f1.8 or the Pentax-M 40mm f2.8 vs the Pentax DA 40mm F2.8mm XS Lens It would be interesting to know maximum off-axis ANGLE of various lenses as well (as measured at the corners of the APS-C sensor). Is there any way to derive that mathematically? Thanks again for any reply you may have time to give. - - - I don't have a K-7 to compare with my K-5 but it seems that if someone had those two camera models and lenses that were close to the same for the comparison of film-era lens vs digitally optimized lens that we could have some side-by-side comparisons. Another comparison could be made between the DFA 100mm f2.8 and the earlier film 100mm f2.8 macro designs. With regard to my question of calculating the off-axis angle of various lenses... It seems that the angles we are talking about could be calculated from knowing the diameter of the rear lens element and the diameter of the image circle that covers the sensor and the distance between that rear element and the sensor. Doesn't digitally-optimized just mean a design that allows the use of the smallest diameter of rear lens element that can still cover that sensor image circle? -- 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.
