You asked
Is the leica vario elmarit sl 70 200mm f 2 8 asph good on aps c?
Yes, it works well on APS-C, and it's a good reason to pick that system. On an APS-C L-Mount body it frames like a 105-300mm on full frame, and f/2.8 gives about the depth of field of f/4.2. That's enough reach for sport, wildlife, or headshots from across the room, with a bit more background blur than a slower zoom would give you.
It's a sensible choice on any of these APS-C bodies:
If you shoot people, the portrait lens guide explains why a 70-200mm suits tight headshots, and the wildlife and sport guide covers how much reach you need for different subjects.
Written by Claude from this site's pages.