Originally posted by johnha Hi Rick, thanks for doing all these tests, analysing the results and placing them in context. These are interesting threads, not just for the results but also a technical discussion on how best (or not) to measure lenses.
What I'm looking to get out of them is whether the D-FA & DA lenses are so much better than 'legacy' 645 lenses that they become the 'preferred' options (despite the price difference) for getting the best out of the D or Z - and whether my 6x7 lenses on the adapter are capable of 'good enough' results.
Given your assertion that in real world images, the Z is lens rather than sensor limited, could this be taken that the differences between the D and Z sensors (within the bounds of ISO capability) are perhaps less than the 'on paper' comparison?
John.
The 645z is sensor-limited in a few narrow cases, but those cases occurred most broadly with my one D-FA lens. I only own one modern D-FA lens, the 55/2.8. The others I cannot afford at present (and "present" may be for quite a while--I have to absorb the expense of the camera and a versatile capability, which required lots of stuff like flashes and longer lenses, and then there was the Sinar P Expert Kit that happened to come my way, and the used Canon 5DII...).
Look at the test for the 55. What I see there that I don't see with the FA lenses is wide-open performance. At f/11, they are all pretty good, and some are excellent. But wide open, the 55 D-FA is more noticeably ahead. All the better Pentax lenses can approach the boundaries of the sensor in the center of the frame at f/11, but the 55 can do it over a wider range of apertures. Of course, it's a double-gauss normal lens--one of the easiest designs to correct to a very high degree. But I suspect the same holds true for the 28-45 and the 90. The 90 is better than the 120, according to a review by a commercial jewelry photographer (whose test I could not better for practical value), but not by much. I suspect the 28-45 is better than the 35 prime at any given aperture, but especially wide open.
I would suppose that I would prefer the D-FA lenses in all cases. But preference is one thing; choice is another. My choices have to answer to more constraints than do my preferences.
I only test one 67 lens--the 165/2.8. It's the only really fast long lens in the 67 line, and I don't have the 150/2.8 645 lens. The 165 was noticeably softer wide open than the 200/4 or the 120. Perhaps that's not a fair comparison, and I don't recall the images well enough to know how they compare at f/11. I'm thinking to redo that test with a different subject, and compare it to the Carl Zeiss Jena Sonnar 180/2.8, for more than just sharpness (neither are really sharp wide open, but they make superb portrait lenses, where surgical sharpness will reveal things the sitters often don't want to see).
Tonight, I'm adding the two perspective shift lenses I own to the series.
Rick "leaving the 120, the A* 300, the 80-160 and the 75LS still to come" Denney