Originally posted by Mistral75 That's longitudinal chromatic aberration: magenta in front of the focal plane and green behind it.
All fast lenses but truly apochromatic ones suffer from longitudinal chromatic aberration.
The only apochromatic 50ish lens I know of is the Zeiss Otus Apo-Distagon T* 55mm f/1.4.
Correct, this is par for the course. Shoot the same scene with the DA* 55, Sigma 50 1.4, or even the DA 70 ( I have all three) and you will see the same but worse.
As long as it is controlled enough to be easily correctable in camera or in post I don't think it is big issue.
We'll have to see more samples from the final production version to get a better feel for how well fringing is controlled, but zero fringing is an unrealistic expectation.