So I am pin the process of preparing for an upcoming trip and was testing my lenses and noticed that on my Z 70-200, when I shoot a test chart at f/8, ISO 100 or ISo 64, and 2" the image was a bit soft (this was on a tripod, indoors, with IBIS/VR off, and triggered by a remote so I wasn't touching the camera; I also have EFCS turned on).When I upped the ISO to ISO 400 and got it to around 1/4 of a second, the image was sharp (everything else was the same). Going further (beyond 1/4 second the image stayed sharp). I only noticed this at f/8 though, as my f/11 shots even at slower shutter speeds, were sharp. (The sharpeness / lack of sharpness is also even across the frame, so it's not a defocusing problem.)The only two possibilities I can think of that would explain this would be:1.) The camera did not in fact lock focus even though it says it did (most likely reason.)2.) There is shutter shock that can cause softness around 1.3" (even though having EFCS turned on). Softness didn't appear in images that were shot at 2" or longer, or faster than about 1/2 second (I didn't try every since possibility, just those ranges).

sirhawkeye64 wrote:So I am pin the process of preparing for an upcoming trip and was testing my lenses and noticed that on my Z 70-200, when I shoot a test chart at f/8, ISO 100 or ISo 64, and 2" the image was a bit soft (this was on a tripod, indoors, with IBIS/VR off, and triggered by a remote so I wasn't touching the camera; I also have EFCS turned on).When I upped the ISO to ISO 400 and got it to around 1/4 of a second, the image was sharp (everything else was the same). Going further (beyond 1/4 second the image stayed sharp). I only noticed this at f/8 though, as my f/11 shots even at slower shutter speeds, were sharp. (The sharpeness / lack of sharpness is also even across the frame, so it's not a defocusing problem.)The only two possibilities I can think of that would explain this would be:1.) The camera did not in fact lock focus even though it says it did (most likely reason.)2.) There is shutter shock that can cause softness around 1.3" (even though having EFCS turned on). Softness didn't appear in images that were shot at 2" or longer, or faster than about 1/2 second (I didn't try every since possibility, just those ranges).Sort of figured this out. Of course the corners are decently sharp but after looking at some test chart samples from reviews, what I observed was (1) likely error on my part (where the entire frame was soft), (2) the corners are only sharp (tack sharp let's say) at certain focal lengths (in particular, 105mm, which I didn't really try). It's less sharp at most other FLs but probably not noticeable in practice. At least on a good note, the softness I see in the corners is just a result of the performance of the lens and not a lens-specific issue (decentering for example).  Upping the ISO so I wasn't shooting at 1.3" did help, although I can't exactly say what was causing the bit of softness, as I redid the test again with similar results, but after increasing the ISO and getting to 1/4 or 1/8 of a second, the center was sharp as was mid-frame, but the corners were a tad sharp, but likely for the reason I mentioned above.