Hi,

When deciding on a telephoto lens, should I be focusing on putting a quality APSC lens on an APSC body, and a full frame lens to match a full frame body?
If I get a full frame lens for an APSC body like the 7D Mark II, how will I know that that combination will deliver sharp results?

I am currently looking at something like the EF 24-70mm f/2.8L II or a Tamron SP AF 70-200MM F2.8 VC USD depending on which camera I get (7D MII or 5D MIII).