Features:

• 50mm standard lens with f/1.4 maximum aperture for Canon SLR cameras
• 2 high-refraction lens elements and Gaussian optics help eliminate astigmatism
• Delivers crisp images with little flare at the maximum aperture
• Extra-small Micro USM focus adjustment and full-time manual focusing
• Measures 2.9 inches in diameter and 2 inches long; 1-year warranty

Editor Reviews:

Product Description:
The CANON EF 50MM f/1.4 USM is a standard lens featuring superb quality and portability. Two high-refraction lens elements and new Gaussian optics eliminate astigmatism and suppress astigmatic difference. Crisp images with little flare are obtained even at the maximum aperture. Max. Diameter & Length - 73.8mm x 50.5mm

Amazon.com Product Description:
When accuracy matters, the Canon EF 50mm standard lens steps to the plate. The lens offers two high-refraction lens elements and new Gaussian optics, helping eliminate astigmatism and suppress astigmatic differences. As a result, the lens provides an image that's extremely close to how your eye perceives a subject, making it excellent for portraits and images that require a natural depth of field. The lens even delivers crisp images with little flare at the maximum aperture. Compact and affordable, the EF 50mm is the only lens in the EF system to offer the extra-small Micro USM while still providing full-time manual focusing. As with all Canon lenses, the EF 50mm carries a one-year warranty.

• Focal length: 50mm
• Maximum aperture: 1:1.4
• Lens construction: 7 elements in 6 groups
• Diagonal angle of view: 46 degrees
• Focus adjustment: Overall linear extension system with USM
• Closest focusing distance: 1.5 feet
• Filter size: 58mm
• Dimensions: 2.9 inches in diameter, 2 inches long
• Weight: 10.2 ounces

Rating : - light, sharp wonderful all around lens
I first bought the 50 f1.8 lens and it is a pretty decent one but then I tried a friend's 50 1.4 and sold my old one to buy this. It is a huge improvement over the 1.8 in that the AF is quick and accurate. I had problems with the AF on the other lens; it frequently hunted in low light. With the Canon 50 f1.4 you can take great photos in rooms with very little light; I have taken everything from pet photos to portraits of children and outdoor scenes with this wonderful lens. Because it is small, it's easy to have in the camera bag at all times. A real bargain in the Canon line-up. I also own the 3L, 135L, 24-105L, etc and use this one frequently. Buy it.