Sigma 50mm f/1.4 EX DG HSM - Sigma SA, Canon EF, Nikon F, Sony A, Pentax K Mount

The Sigma 50mm f/1.4 EX DG HSM is a large-aperture standard prime lens designed for full-frame DSLRs. It features a Hyper Sonic Motor (HSM) for quiet, high-speed autofocus and a rounded nine-blade diaphragm to produce smooth background blur. The optical construction includes aspherical elements to manage aberrations. It was widely regarded as a significant upgrade over standard manufacturer primes of its era due to its physical size and optical performance at wide apertures. Common issues with this model include front or back focusing, which is typical for high-speed DSLR primes; SDS tests these lenses for focus accuracy. The 'EX' finish on earlier versions can sometimes peel or become tacky, so the exterior condition is carefully reviewed. We also check for internal dust and ensure the HSM motor operates smoothly without excessive noise. The large front element should be free from scratches and coating damage.