Hi,Update: I have looked quite a bit at your images and I simply don't know. May be I don't like Capture One rendition?! Hair detail on girl is good, the building seem to show sharpeing artifacts. I guess you use default settings in C1? adding a central crop may give a reference.
I'm not sure I agree. I have been shooting several lenses prolonged periods without finding out problems. Charts don't tell the full story about a lens but they tell a lot about how it is designed to perform. If you do a well designed test comparing two lenses some issues may become obvious.
Also, please don't forget, I'm the one actually saying that the lens is quite OK, based on the charts. I also say that the charts indicate a bent focal plane, and if I'm right the problem can be solved by focusing correctly for 3D subjects. Landscape or repro may show the weakness.
On the other hand, if I am wrong and the issue is not caused by a bent focal plane the lens would be a bad match for a sensor like P65+ or IQ 160. The P65+ has a pixel pitch of 6 microns, corresponding to 83 lp/mm but the 55 mm lens only transfer a few percent contrast at 60 lp/mm, corresponding to 8 micron pixels.
Now, perfect focus does only exists at infinity or in a very narrow plane. So, most parts of our image will be more or less out of focus. So we have four possible options.
- Important matter is in the sharp zone, no important matter is in the weak zone, everything OK.
- Important matter is in the weak zone and we focus on the important matter, just fine.
- Important matter is in the weak zone and focus is in sharp zone, bad luck.
- We have important matter in both zones, bad luck.
What we also need to keep in mind that MTF curves are about sharpness, in a single plane. They say nothing about out of focus areas, coma, ghosting and a lot of other factors that matter a lot.
On the other hand, lens designs are mainly based on MTF curves. The designer sets up a basic design and a computer optimizes the design, based on design criteria, but the engineers use a lot of MTF data.
Zeiss has a very nice article here about the interpretation of MTF curves: http://www.smt.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_31_MTF_en/
There is a page with images illustrating the different aspects of the MTF curves here: http://www.zeiss.de/C12567A8003B8B6F/GraphikTitelIntern/CLN31MTF-KurvenBild1/
and here: http://www.zeiss.de/C12567A8003B8B6F/GraphikTitelIntern/CLN31MTF-KurvenBild2/
Erik if you look at the images I've attached a few posts back, while not being too appealing visually (my apology if they offend anyone) they may tell the lens's story better than a chart or at least add something to the story
And as previously offered (on numerous occasions) a real test/demo with a real product is worth more than others' written opinions. You shoot the camera in your own environment and at your own pace and then you can play with the raw files to your heart's content!