Review

Panasonic 200mm f/2.8 is very sharp, tack sharp, even at f/2.8. For the entire frame, the sharpness graph is almost completely flat, indicating tack-sharp performance from center to corner, even when shot wide open. According to our measurements, there's an extremely minimal amount of corner softness at f/2.8, which gets sharpened if you stop down some, between f/4-f/5.6. However, despite the graphs, the difference in sharpness from the center to the corners at f/2.8 is insignificant.

Wide-open down to f/5.6, we observed optimal sharpness from the 200mm f/2.8, with tack-sharp quality across the entire frame. Once you stop down to f/8, however, slight diffraction-related softening begins to appear. It's still incredibly minor at f/8 and even still minimal at f/11. It's more pronounced once you hit f/16, which isn't surprising, though it's not terrible. At f/22, though, we definitely notice some softening.

https://www.imaging-resource.com/lenses/panasonic/200mm-f2.8-power-ois-leica-dg-elmarit/review/

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