Constant F2.8 aperture across a versatile 28-105mm zoomMany conventional zoom lenses which have a reach up to 105mm do not offer a constant F2.8 aperture, usually dropping to F4 at the long end. But the Sigma 28-105mm F2.8 Dg Dn | Art delivers the same impressive light-gathering and depth-of-field benefits across the whole focal range. The lens offers all of this along with extremely high optical performance thanks to the thorough suppression of optical aberrations within each lens group. And with its outstanding close-focusing capability when zoomed in, macro-style results are also possible.a versatile F2.8 aperture perfect for portraits and low lightWith its fast aperture across the whole focal range, the Sigma 28-105mm F2.8 Dg Dn | Art is a true workhorse lens that can be used for almost any type of photography. Scenic photographers can shoot wide-angle landscapes, using the F2.