Keith B. wrote:
Pure speculation: It is conceivable that some specific lens designs may be relatively "immune" to sensor stack issues, while others may suffer more noticeably. Sort of like the idea that lenses can be designed to be less sensitive to physical assembly errors. The Thypoch Simera Z 28/1.4, which *everyone says* is the exact same optic as the M, E, Z, and RF versions, seems not to have the lowered overall sharpness and/or the irretrievably blurred peripheral zones (when used on my Z cameras) that are commonly attributed to stack thickness issues when lenses are switched between camera brands.
Certainly some designs can suffer less, and maybe the Thupoch's are designed for some kind of average stack thickness to perform reasonably on all common stacks. The 28/2, 35/2 and 50/2 APO-Lanthars are not like that though as the VM versions really suffer adapted on E much more than some others from the CV lineup at equal FLs.
Juha Kannisto wrote:
I think the VM vs. E/Z MTFs were already analyzed early in this thread (p.3 #6). Search results indicate that Cosina explicitly labels their MTF charts as "Calculated Values" 計算値 in their detailed product specifications and technical guides, so they are probably not measured results from a test bench.
It seems that e.g. Sigma also generally presents identical MTF charts for the E-mount and L-mount versions of the same lens model. I believe they also optimize (their modern mirrorless lenses) for each sensor stack as L-mount is for their own cameras but E-mount is where they sell more. I've had some of their lenses in both E and L (Sigma fp) and never noticed any visible IQ performance differences between the mounts....Show more →
L mount is a little crazy. It's hard to verify, but I've heard that Leica L mount cameras are in the 1.0-1.2mm range, Sigma L mount cameras are in the 1.3-1.5mm range, and Panasonic L mount cameras are around 2mm (like Sony). So it would not surprise me if Sigma split the difference for their L mount cameras, made it 1.3-1.5mm and that's what they optimize for with their lenses. I would be surprised if they further optimized for Sony. But it might perform close to optimal for many of their lenses anyway.
I think Z mount is like 1.1mm and Leica M is in the .5-.8mm range. So I would expect you to see less degradation on many M mount lenses used on Z mount vs E mount.
All of the above is pure conjecture...really all of it. So rake me over the coals, I'm fully acknowledging that I can't "prove" anything. . (Not suggesting you would do that Juha.)
Justin Stone wrote:
I mean it looks pretty good to me. Camera labs liked it. Short of perfect in the corners, but that’s a decent result.
Yes indeed. The extreme corners are a bit softer wide open, improve a lot already at f2.8 and are more or less perfect from f4 onwards.
The 50 APO already has great corners wide open, the 35 APO has them at f2.8 and the 28 APO at f4. For me this seems normal behaviour when going from 50 and 35 to 28 with lenses that have similar design parameters (type of glas, size and weight) and to be expected. And excellent IMO.
tsdevine wrote:
L mount is a little crazy. It's hard to verify, but I've heard that Leica L mount cameras are in the 1.0-1.2mm range, Sigma L mount cameras are in the 1.3-1.5mm range, and Panasonic L mount cameras are around 2mm (like Sony). So it would not surprise me if Sigma split the difference for their L mount cameras, made it 1.3-1.5mm and that's what they optimize for with their lenses. I would be surprised if they further optimized for Sony. But it might perform close to optimal for many of their lenses anyway.
I think Z mount is like 1.1mm and Leica M is in the .5-.8mm range. So I would expect you to see less degradation on many M mount lenses used on Z mount vs E mount.
All of the above is pure conjecture...really all of it. So rake me over the coals, I'm fully acknowledging that I can't "prove" anything. . (Not suggesting you would do that Juha.)...Show more →
I think they pretty much have to optimize for Sony too to compete with all the Sony and Tamron offerings, and they are very competitive there as well, always doing well in reviews. And I think there's never been any review showing a better performance of their lenses on L mount over E or the other way around. Personally I've been very happy with the IQ of their lenses on both mounts too (I traded away my L-mount lenses eventually as I mostly use my Sony cameras and Sigma wasn't getting too much use anymore). I can't prove anything about their approach either
Kolari once stated that Sigma fp sensor stack was measured by them as ~1.3mm (when one of the forum member sent his fp to them for ultra thin stack operation). I've also read that there appears to be some variation between different L-mount cameras.
Juha Kannisto wrote:
I think they pretty much have to optimize for Sony too to compete with all the Sony and Tamron offerings, and they are very competitive there as well, always doing well in reviews. And I think there's never been any review showing a better performance of their lenses on L mount over E or the other way around. Personally I've been very happy with the IQ of their lenses on both mounts too (I traded away my L-mount lenses eventually as I mostly use my Sony cameras and Sigma wasn't getting too much use anymore). I can't prove anything about their approach either
Kolari once stated that Sigma fp sensor stack was measured by them as ~1.3mm (when one of the forum member sent his fp to them for ultra thin stack operation). I've also read that there appears to be some variation between different L-mount cameras....Show more →
I have a ton of Sigma lenses and I'm very happy with them as well. But the designs might be forgiving enough that a design that works well for 1.3ish mm filter stack may work nearly as well for Sony's 2mm. If they optimized for 2mm then it might be a little rough on a Leica camera. In any case, it's a little crazy there is so much variability in L mount filter stack thickness depending on whose L mount camera you look at.
. (Not suggesting you would do that Juha.)
