Important details on the introduction page should be read prior to viewing these crops. Those details are not repeated here.
Zone of focus
The same 70-200mm f/2.8L IS II is shown twice in the crops that follow. That’s because a very small focus difference can scarcely be detected at the point of focus, but the zone of sharp focus at f/2.8 does shift, and the left edge is visibly blurred with one series. Such are the changes caused by small focus nuances.
In this case, it shows that the lens is not symmetric, since the right side remains mostly unchanged. It shows that there is not perfect alignment left-to-right, not too surprising for such a complex lens. With most photos, this won’t show up, since subject matter is not planar, but consider that the left-edge blur requires f/8 to overcome, and it no longer seems a nit-picker issue at all.
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