You asked
Is the canon ef 70 200mm f 4l is usm good on aps c?
Yes, it's a good match for APS-C. On a Canon APS-C body it frames like 112-320mm on full frame, which is plenty of reach for sport from the sideline and for larger animals. The f/4 aperture gives about the depth of field of f/6.4 there, so it's less blurry than the f/2.8 zooms, but it's lighter and cheaper.
I'd pair it with a body that handles fast action well:
If you shoot birds, you'll want more reach than this. See Wildlife and sport for longer options.
Written by Claude from this site's pages.