Sigma 80-400mm f/4.5-5.6 EX APO DG OS - Nikon F, Canon EF Mount

The 80-400mm was Sigma’s first lens to feature Optical Stabilisation (OS), helping to counteract camera shake at longer focal lengths. It is an EX-series lens, denoting a higher build quality and superior optical performance using APO (Apochromatic) design principles. While it uses a motor for autofocus, it is generally slower than HSM models, making it better suited for stationary wildlife or landscape photography than fast-action sports. Check the OS system by listening for the engagement hum and observing the viewfinder image for stability. SDS tests the zoom mechanism for smoothness, as the heavy internal glass can lead to wear over time. Verify that the AF/M and OS switches click firmly into place and that the lens mount shows no excessive play when attached to a body.