The area enclosed by the red box is represented below at 100% magnification. No sharpening, color, or contrast adjustments were made.

Red circle: I looked at this area to see if there was any flare or "bleed" from the white towel into the dark railing.
Blue circle: The area I focused on.
Green circle: Another area to look at for sharpness.

1) Point of focus. I tried to focus each lens to get the brick area indicated by the blue circle (image at the top of this page) as sharp as possible, but there may still be variations in the actual point of focus.

2) Representative sample. I am using my own equipment for these tests, some purchased new but other pieces purchased used. I do not know the history of the lenses I purchased used, and so some of them may have been disassembled or serviced prior to their coming into my possession. At any rate, the lenses tested here are assumed to be a "representative sample" of what is commonly available. Variations in manufacture among other things may skew the results, and so these test images may or may not accurately reflect what you can expect from a different lens specimen.