The Sigma 150-500mm f5-6.3 DG OS HSM superzoom has the most important aspect of any modern long-focus lens – an efficient AF drive system. This is very much the Sigma superzoom’s forte. As well as being quick its motor is also quiet and acts internally, so the manual-focusing ring remains motionless but can still be used at any time to make adjustments.

The Sigma 150-500mm f5-6.3 DG OS HSM lens is fairly bulky: in part this is probably due to the Optical Stabiliser that is fitted inside the newer Canon, Nikon and Sigma versions (but not the older Pentax and Sony models). The OS has two modes to accommodate both static and panning situations but did not always improve the MTF figures recorded during testing. It does, however, settle the image for more accurate composition and easier manual focusing.

The manual-focusing ring is heavily obstructed when the tripod platform is attached. This is obviously a design trade-off: the tripod platform has been generously sized and shaped to provide a comfortable grip. Removing the tripod platform means taking the lens off the camera, after which additional steadying will be available only via the camera’s tripod-screw. This would result in poor balance, so manual-focusing (or focus adjustment) is easiest carried-out with the tripod platform in place, using an unnaturally high grip on the ring with the left elbow almost horizontal.

The zoom ring has a fairly short throw but the extended tripod platform also obstructs this a bit.