Sigma's budget APS-C ultra-wide zoom — 15-30mm equivalent coverage at a very affordable price.
The Sigma 10-20mm f/4-5.6 EX DC launched in 2005 as one of the first affordable ultra-wide zooms for APS-C DSLRs. Covering approximately 15-30mm equivalent, it made ultra-wide photography accessible to budget-conscious enthusiasts long before most alternatives existed.
Optically decent for the era and price — sharp in the centre from f/5.6 with expected edge softness. The EX designation indicates Sigma's professional tier with quality construction. Variable aperture limits low-light use. Adequate for landscape and architectural work.
Available in multiple DSLR mounts including Pentax K. 77mm filter thread — accepts standard screw-on filters. Weighs approximately 470g. No weather sealing. DC designation means APS-C coverage only. Minimum focus distance 24cm. HSM motor on some versions.
Very cheap used. The Sigma 10-20mm f/3.5 EX DC HSM improved with a constant f/3.5 aperture. Modern ultra-wide alternatives from Tamron and Tokina are optically superior. Only worth considering at bargain prices. Check for smooth zoom action and clear optics.