Don't get the 1.2. DSLRs can't handle off-axis light generated by fast lenses (<1.4 f number) very well and actually automatically adjust there ISO upwards to compensate (without your knowledge). This has generated a lot of debate in the photo community but the evidence seems to suggest that DSLRs do raise their ISOs automatically with these fast lenses. That should be reason enough to save your money and get a slightly slower lens IMO.