there really isn't much need to shoot below 1/30th because IS won't stop motion blur on your subject, for that you need higher SS and in many lighting conditions, that's where you want a fast lens. this rumor really only makes me glad I have a 1.4...now come on canon, lets have at a new 50mm 1.2!!!!! (or will sigma beat ya to the punch?)
Lenses of f1.2 are fine for thin dof, but on *digital* they don't gain much speed over f1.4 because the iso has to be raised even more (without telling the user) to compensate for the light being lost .. and higher mp sensors will worsen this effect.
1+1 = Canon won't update the f1.2 lens, and Sigma won't produce one as they design for multiple systems and wide appeal and not a very special high-budget crowd like Canon the the 50/1.2
True, but, the difference's between 1.2 and 1.8 are a bit greater.
And, with sigma now and their ART line, they are stepping up their quality and their game. They have enough cheap lenses with mass appeal, the ART line seems to be trying to change that reputation.