Sigma 28-70mm f/2.8 EX Aspherical DF - unknown Mount

The Sigma 28-70mm f/2.8 EX Aspherical DF is a fast, constant-aperture standard zoom lens for full-frame cameras. As part of Sigma's professional EX series, it features a Dual Focus (DF) system which decouples the focus ring during autofocus for improved handling. The f/2.8 aperture throughout the zoom range provides consistent exposure and shallow depth-of-field control, suitable for portraits and low-light event photography. Used units should be checked for the integrity of the 'Zen' matte finish, which is prone to peeling or becoming sticky on older EX models. Ensure the DF mechanism engages correctly when switching between manual and autofocus. We inspect the aperture blades for oil and verify that the zoom action is consistent. Like many older Sigma lenses, internal dust is common but rarely affects image quality unless excessive.