The Sigma 1750mm f/28 EX DC OS HSM lens (herein referred to as the 'Sigma 1750mm'), by contrast, takes things up several notches in all areas, from general build quality to performanceSigma's 1850mm EX series macro lens is specially designed for Nikon digital SLR cameras with a minimum focusing distance of cm (79 inches), making it suitable for a wide variety of subjects The lens offers a large aperture of F28 throughout the entire zoom range, along with a maximum magnification of 13 for closeup macro photographyThe Sigma 1750mm f/28 EX DC OS HSM Lens is shown mounted on a Canon EOS 60D above With a wide open f/28 aperture, the Sigma 1750mm f/28 EX DC OS HSM Lens is impressively sharp in the center throughout the focal length range with 50mm showing very slightly reduced sharpness The corners are soft at f/28 with the 50mm corners looking the best Sigma 18 50mm F 2 8 Ex Dc Lens Reviews Specification Accessories Lensbuyersguide Com Sigma 18-50mm f2 8 ex dc macro pentax ...