Sigma 30mm f/1.4 EX DC HSM
This lens is excellent lens for price and image quality. I can tell the reason here, you only pay about 1/3 of EF 35mm f/1.4L USM and you get almost the similar result. Of course EF 35mm f/1.4L USM better for image quality, but sigma quality isn’t 1/3 of the canon quality. This lens is made exclusively only for APS-C camera (1.6 crop factor) so if you use full frame camera you can skip this review. This lens also has HSM (HSM stands for Hyper Sonic Motor) similar with USM(Ultra Sonic Motor) in Canon term. Compare with EF 35mm f/1.4L USM isn’t really fair because they have big difference in price. Maybe you can compare this lens with EF 35mm f/2 (price not much different). I think Sigma 30mm f/1.4 EX DC HSM better than EF 35mm f/2; you get wider aperture (1.4 vs 2), HSM (EF 35mm f/2 don’t have USM); but consider the weakness you only can use this lens on APS-C camera. Use full frame camera 35mm become 35mm, but 30mm (with APS-C camera) become 48mm; seems EF 35mm f/2 has wider focal length. But I don’t think full frame camera user will use EF 35mm f/2, they will use EF 35mm f/1.4L USM for better image quality, so I think you only can compare Sigma 30mm f/1.4 EX DC HSM and EF 35mm f/2 attached with APS-C camera (not the full frame camera).
Lens Construction: 7 Elements in 7 Groups
Angle of View: 45 degrees (SD format)
Number of Diaphragm Blades: 8 Blades
Minimum Aperture: F16
Minimum Focusing Distance: 40cm / 15.7 inches
Maximum Magnification: 1:10.4
Filter Size Diameter: 62mm
Lens Hood: DiaPetal Hood
Dimensions Diameter: 75.5mm X Length 59mm
2.97 inches x 2.3 inches
Weight: 430g/15.2 oz.
Other reviews can be seen here: http://www.the-digital-picture.com/Reviews/Sigma-30mm-f-1.4-EX-DC-HSM-Lens-Review.aspx