Sharpness at 15mm

Our sharpness tests are carried out by photographing a real-world subject rather than a test chart. The Canon RF 15-35mm f/2.8 L IS USM was attached to a Canon EOS RP, which in turn was mounted on a sturdy tripod. Self-timer mode was activated to steady the camera completely. Any slight tonal changes you may see across the crops are a result of slight changes in natural light during the shooting session.

The full frame at 15mm

At the centre of the image, sharpness is very good at the widest aperture of f/2.8. It becomes slightly sharper at f/4 and up until f/11 where the sharpness drops off a little. At f/16 and f/22, the softest results can be seen, but the overall impression of sharpness is good when viewed at normal printing or web sizes. At the corners, the best sharpness can be seen between f/11 and f/22.

Aperture	Centre Crop	Edge Crop
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22