Sharpness at 35mm

For this test, the Sigma 18-200mm f/3.5-f/6.3 Contemporary Lens was mounted on a Canon EOS 750D, which in turn was mounted on a sturdy tripod. Exposure delay mode was activated. Tonal and colour variances across the crops are due to changes in natural light during the session.

The full frame at 35mm

At 18mm, the centre of the frame is at its sharpest between f/4.0 and f/11. At f/16 and f/22 it’s a little softer (when examining at 100%) down to diffraction. In the corners at this focal length, sharpness is reasonable at 100%, and more than usable at normal printing or web sizes. At f/16 and f/22, again it’s a little softer. As the lens is not capable of super-wide apertures, even at the widest points there’s not a hugely marked difference between sharpness in the centre and at the edges.

It’s a similar situation across all of the different focal lengths, with a good degree of sharpness across the frame - especially if you’re looking at an image at normal printing or web reproduction sizes.

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