Sigma 28-135mm f/3.8-5.6 Aspherical IF Macro - unknown Mount

The Sigma 28-135mm f/3.8-5.6 Aspherical IF Macro is a standard-to-telephoto zoom lens compatible with full-frame and APS-C film and digital SLR cameras. It features internal focusing (IF), which ensures the front element does not rotate during use, facilitating the use of circular polarising filters. The lens includes a dedicated macro switch, allowing for a maximum magnification ratio of 1:2 at the 135mm focal length. Aspherical lens elements are utilised to minimise distortion and spherical aberration. Second-hand examples should be examined for the functionality of the macro switch, which can sometimes become stiff or fail to engage correctly. SDS verifies that the internal focusing mechanism operates smoothly without excessive noise. The rubber zoom and focus rings are prone to becoming tacky over time, so these are checked for texture and adherence. We also inspect the optics for any signs of haze or fungal growth which can affect image contrast.