Sharpness at 70mm

For this test, the Sigma 50-100mm F/1.8 DC HSM Art lens was attached to a Canon EOS 80D body, 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 70mm

Centre-frame sharpness at all apertures at 50mm is impressive. If you examine at 100% in the crops, you’ll see that f/16 is a little less sharp than the others, due to diffraction. Corner sharpness is softer than the centre of the frame at the wide apertures of f/1.8-f/4. After this, the difference between the centre and the corner is less marked.

At 100mm, centre sharpness is a little softer at the widest apertures of f/1.8, f/2.0 and f/2.8. It gets increasingly sharper until f/11, where it becomes a little softer again once it hits f/16. Corner sharpness is again softer than the centre of the frame at wide apertures f/1.8-f/4.0. At f/5.6 through to f/16 the difference between the centre and the corner is less marked.

Overall the impression of sharpness when looking at images at normal printing or viewing sizes is very good.

Aperture	Centre Crop	Edge Crop
f/1.8
f/2.8
f/4
f/5.6
f/8
f/11
f/16