Again and again people ask me how exactly I test the sharpness of lenses. This is why in this post I am going to explain my test method.
For all tests, the camera is mounted on a tripod, I use release the shutter via wifi and if possible I use the electronic shutter. This ensures that the result is not influenced by vibrations.
I always use the camera with the highest resolution available to me and if possible a high-res mode. In case of shallow depth of field, I take several pictures and refocus for every shot to make sure there are no focus errors. The samples I use for my reviews are always 100% crops at base ISO.
I always refocus on the image borders to test their sharpness. If I suspect a significant field curvature, I test it separately.
I have been asked if the post cards I use as my test subject are sharp enough. If they are the limiting factor you are going to see the pressure grid.
Here is an example what this looks like:
If you do not see the pressure grid, the post cards were sufficient as the test subject.
If you still have doubts, take a look at my comparion between the Olympus M.Zuiko 25mm F1.2 Pro and the Olympus M.Zuiko 12-40mm F2.8 Pro. Although this are expensive lenses and part of Olympus Pro line, the difference between the maximum aperture and F/5.6 is clearly visible.
Even if a different subject would show a difference at F/5.6, honestly, there is a point where a lens is just sharp enough. I am interested in real photography and I do not think that there is a picture that would suffer from the amount of sharpness that those two lenses display in my test.
If you have any more questions about how I test the sharpness of lenses just leave a comment!