here's a review
sigma 50mm F1.4
and here's Sigmas web site
Sigma
Street price • $500 (US)
• £329 (UK)
Date introduced March 2008<<<< release date ???????
Maximum format size 35mm full frame
Focal length 50mm
35mm equivalent focal length
(APS-C) 75mm (1.5x)
80mm (1.6x)
Diagonal Angle of view (FF) 47º
Diagonal Angle of view (APS-C) 31º
Maximum aperture F1.4
Minimum aperture F16
Lens Construction • 8 elements/6 groups
• 1 Aspherical element
Number of diaphragm blades 9 (rounded)
Minimum focus 0.45m (1.5 ft)
Maximum magnification 0.14x
AF motor type • Ring-type ultrasonic
• Full-time manual focus
Focus method Unit focus, internal to lens barrel
Image stabilization • None
Filter thread • 77mm
• Does not rotate on focus
Supplied accessories • Front and rear caps
• Lens Hood
• Soft Case
Weight 505g (17.8 oz)
Dimensions 84.5mm diameter x 68.2mm length
(3.3 x 2.7 in)
Lens Mount Canon, Nikon, Pentax, Sigma