50mm F1.8 Canon STM lens

MikeLinn

Vitaliy_Kiselev

vs 50mm USM

http://www.focus-numerique.com/test-2498/duel-canon-ef-50mmf14-usm-vs-ef-50mmf18-stm-1.html

Vitaliy_Kiselev

Used wide open at ƒ/1.8 or ƒ/2, the lens exhibits substantial corner softness. On a sub-frame camera like the 7D it's not quite as noticeable as on a full-frame camera like the 1Ds mkIII, because the sensor doesn't capture the entire field of view offered by the lens. Either way, at ƒ/1.8 there's only a small area of sharpness in the center of the frame, which quickly gives way to softness going out towards the corners.

Stopping down to ƒ/2.8 improves sharpness dramatically: on the sub-frame 7D, images produced are almost tack-sharp corner to corner, with a light amount of softness in the extreme corners

http://slrgear.com/reviews/showproduct.php?product=1796