Sharpness at 300mm

For this review, the sharpness test is carried out by photographing a real-world sample, rather than a test chart. The Canon EF 70-300mm f/4-5.6 IS II USM Lens was mounted on a Canon EOS 5D Mark IV, which was in-turn mounted to a sturdy tripod. Exposure delay mode was activated to prevent camera-shake. Any changes in tone you might see across the crops are due to natural light changes during the shooting session.

The full frame at 300mm

At 300mm, centre sharpness is very good at f/5.6 (the widest aperture), but is a little sharper at f/8. It’s excellent at f/11 and f/16, dropping a little again at f/22. At f/32 it’s noticeably soft, while at f/45 (the narrowest aperture), it’s even softer and is best avoided if possible. At the edge, it is sharpest at f/16 and f/22.

Aperture	Centre Crop	Edge Crop
f/5.6
f/8
f/11
f/16
f/22
f/32
f/45