Sharpness Cont... 2

Sharpness at 100mm

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 100mm

As with 70mm, there's little difference between the sharper aperture settings and when it's wide open or closed down at 100mm. We can detect a slight shift in sharpness at the edges with the sharper results appearing at around f/5.6 - f/11.

Aperture	Centre Crop	Edge Crop
f/4
f/5.6
f/8
f/11
f/16
f/22
f/32