Sigma's original 30mm f/1.4 for APS-C — the pre-Art predecessor that started Sigma's fast prime reputation.
The Sigma 30mm f/1.4 EX DC HSM is the original APS-C fast prime that preceded the hugely successful Art version. Launched in 2005, it was one of the first affordable f/1.4 primes specifically designed for APS-C sensors.
Optically good for its era — sharp from f/2 with some field curvature and focus shift. The f/1.4 aperture was unusual for APS-C at this price. HSM motor for fast, quiet AF. The EX designation indicates professional build quality.
Available for Canon EF-S and other mounts. 62mm filter thread. Approximately 430g. No weather sealing. APS-C coverage. DC designation. HSM motor. Minimum focus distance approximately 40cm.
Available used very cheaply. The Art version (2013) is dramatically better — sharper with much improved AF consistency. This original version has more focus issues. Only worth considering at very low prices. The Art version is strongly preferred.