100–300mm · f/4
The Sigma AF 100-300mm f/4 APO EX IF is a well-built telephoto zoom with a constant f/4 aperture, offering solid optical performance especially at shorter focal lengths. Build quality is high with metal construction and non-rotating front element. However, sharpness can degrade beyond 200mm, with potential de-centering issues on full-frame. It is heavy and large but suits users wanting a fast, durable zoom for APS-C or full-frame, though it may not be ideal for wildlife or portraits due to its range.