what is sigma ex mean
From Wikipedia, the free encyclopedia. Sigma 30mm f/1.4 EX DC HSM mounted on a Canon EOS 40D, hood attached. The Sigma 30mm f/1.4 EX DC HSM is a wide-aperture photographic lens made by the Sigma Corporation, equipped with Hyper Sonic Motor (abbreviated HSM, Sigma's trade name for photo lens focusing technology using ultrasonic motor).