Sharpness Cont... 3

Sharpness at 135mm

All the test pictures were taken at the same time using a Manfrotto Tripod. As with any zoom lens, it's always sharpest in the middle of the zoom range. Go out to either end of the range and sharpness drops off. This does happen with the Canon EF 70-300mm f/4-5.6 L IS USM, especially at the telephoto end. For this test, the lens was attached to a Canon EOS 5D MkII which was on a short self timer with mirror lock up enabled.

The full frame at 135mm

At 135mm, the lens allows an extra 1/3 stop aperture from f/32 to f/36 but loses a third of a stop at the wide setting. There is a mild difference between this setting and a typically sharper setting such as f/8 or f/11.

Aperture	Centre Crop	Edge Crop
f/4.5
f/5.6
f/8
f/11
f/16
f/22
f/32
f/36