if it's good as the Sigma 35mm f/1.4 Art… i will be more than happy !
Lens Construction: 13 Elements in 8 Groups (five more elements than in the 50 f/1.4 EX) with 3 SLD elements, 1 aspherical glass and a floating focus system
Minimum Focusing Distance: 40cm / 15.7 in (vs 45 cm, which is the MFD of most 50mm non-macro DSLR lenses)
Maximum Magnification: 1:5.6 (vs 1:7.4)
Dimensions: (Diameter x Length) 85.4 x 99.9 mm / 3.4 x 3.9 in (vs 83.8 x 68.6 mm / 3.3 x 2.7 in, a significant length increase to fit the 13 elements)
Weight: 470g / 16.6oz