Build quality and handling
Despite being relatively inexpensive to buy, the Sigma 70-300mm f/4-5.6 APO DG Macro's build quality feels good and solid. The lens is reassuringly weighty at 550g and measures 77-119mm, extending to 249mm at its longest zoom setting and shortest normal focus setting, with the lens hood fitted.
Switch to Macro mode using the switch on the side of the lens barrel and it stretches even further to 264mm.
The autofocus motor is quite noisy, but it's reasonably quick. There's no internal focus, so the front element rotates and extends as you focus from infinity down to the closest focus distance but, on the plus side, this enables the printing of a magnification scale on the inner lens barrel, as well as the focus distance scale which is printed around the the focus ring. The focus and zoom rings both have a smooth action and the lens doesn't suffer from zoom creep.
Impressive throughout most of its zoom range, the Sigma's sharpness drops off at the long end of the zoom range, especially towards the edges and corners of the frame. Sharpness at 300mm is poor across the whole frame with small apertures of f/16-32, which you might want to use to increase depth of field in macro shooting.
Despite its APO badge, chromatic aberrations are quite noticeable. Sigma's newer, non-APO 70-300mm OS actually performs rather better in this respect. In some of our tests under dull lighting conditions, image contrast was also a bit lacking.
Taken at 300mm, f/5.6