Review of the Sigma 105mm f/2.8 EX DG

www.sigma-imaging-uk.com Another Sigma full-frame lens, this one offers 1:1 magnification with a minimum focus distance of 31.3cm. Like the 50mm the fast aperture can be stopped down to f/45, or f/32 on Pentax and Nikon bodies. On most APS sized cameras, the lens has a 1.5x magnifi cation effect offering 157.5mm equivalent in 34mm terms. Or an angle of view of around 23°, if you need to know. The lens has a dual-focus function: the focus ring snaps backward and forward between manual and autofocus, making critical adjustments easy and quickly. If you use AF, the lens has a limiting switch so focus stays within a narrow range. Where the Sigma 105mm optic performs well is in its control of chromatic aberration, which remained insignifi cant throughout the aperture test both in the centre of the frame and at the corners. In terms of sharpness the lens is a reasonable performer, and produces decent results, but suffers when placed in comparison to others, with generally consistently lower MTF measurements than the other lenses on test. ……