awilder said:
I originally bought the Planar thinking it would perform at least equal to my last Summicron based on superlative performance I had with the 45/2 G Planar. Critical testing resolution chart testing of my sample did not reveal this to be the case. Repeating the tests on another roll revealed no significant difference from the first roll.
I ran these test prior to Erwin Puts' review of the lens and quite frankly his explanation of minor back focus differences seemed quite plausable to me based on focus bracketing shots with the Planar.
Alan, your original presentation of your results on P.net drew mixed reaction. In other words, not everyone agreed with your conclusion. The links you posted speak for themselves. When I saw your post there, my reaction was that you took some beautiful pictures with this lens, especially with regard to color rendition & saturation.
Since you referred to Erwn's report, I thought it would be useful tp post some of his comments next to yours. Obviously all of his tests were done using a Leica M camera since the ZI was not yet available. And no one does more "critical testing" of resolution than he does.
Regarding comparisons with the Contax G 45/2 Planar:
"The (ZM) Planar wide open is a potent performer and at smaller apertures becomes a master at reproducing with a life-like three dimensionality that was the hallmark of the G-version of the Planar too."
Regarding critical testing of resolution:
"Now at last we have a lens that equals the Summicron-M 50mm and is even a trace better in the curvature of field area. The optical performance of the Planar is simply as good as that which can be expected from the Leica Summicron."
So, when you say that "critical testing resolution chart testing of my sample did not reveal this to be the case," one can safely say that this result is limited to your sample & your interpretation of the results for your sample, given Erwin's testing of a different sample & his interpretation of those results.
Regarding Erwin's discussion of "minor back focus differences:"
"(What) we are talking (about) here is quite small dimensions, a thickness of a handful of human hairs, but it may be significant."
MAY be significant? In other words, Erwin, who pays meticulous attention to detail, did not find ANY difference in his testing. If he had, he would have said so. His discussion makes it clear that in his opinion any real world effects are theoretical. Extrapolationg from his comments to your conclusions is a reach in my opinion.
I think it is also important to note that while Erwin points out the differences in back focus between ZM & Leica lenses, he also makes it clear that NEITHER Leica nor Zeiss have chosen to adjust their focus for the actual film plane. "All ZM lenses had an adjustment in the minus direction, which is in front of the film plane. The Leica lenses were adjusted to the plus side, that is behind the film plane" So, the offset of the back focus in the ZM lenses from the film plane is even less than the difference between the Leica & ZM points of back focus. The point is that the Zeiss & Leica engineers made different choices in where the precise point of back focus should be. As is often the case, the engineers disagreed. And you & Erwin seem to disagree about whether this makes any difference in either real world photography or on test charts.
I found Erwin's report extremely useful in his description of the subtle differences in character between the Leica & ZM lenses - especially in regard to the 50 mm focal length where he found the two lenses to be on par. He enhances these comparisons with an excellent explanation of the differing philosophies of lens design between the two companies & the type of imaging that each is trying to achieve.
