Sigma 100-400mm F5-6.3 DG DN OS | Contemporary

Reviewers found it sharp in the centre throughout the range, with some softening at 400mm f/6.3 and in the corners that improves by f/8. Contrast and colour are good, and testers generally put it a little behind Sony's 100-400 GM and the Tamron 150-500mm at the long end but far ahead on price.

The stepping-motor AF is accurate and fine for birds and casual sports, but slower to acquire and track than linear-motor lenses on fast subjects. Reviewers also mention the lack of sealing and that it extends a lot when zoomed.

Owners like it as a light, low-cost first telephoto for birds, kids' sports and zoo or safari trips, and many say the push-pull zoom is fast to use. The 67mm filter thread and modest weight make it easy to pack.

The usual complaints are hunting in low light, f/6.3 at the long end, and softness at 400mm compared with more expensive lenses. Some owners wish the tripod foot came in the box and worry about using it in rain without sealing.