Quote...Oh, I use the 50mm 1.8 II at times and it often hunts for focus in dim lighting conditions where the 24-70 snaps on to the target almost instantly.
This may have more to do with the way you shoot and focus or the way you set up the AF area selection modes with your 5DM3. How are you focusing and what AF selection mode are you using? I rarely have hunting issues with any of my lenses in lowlight situations, especially with the 24L II or 50L.
That's because your lenses aren't the 50mm 1.8 II.