Well if you shoot full frame , you have to crop anyway and you get even more noise .i'm no animal shooter but my M50 has terrible low light noise , even my best images when you go to blow up get built in noise surely a nice F/F would be better for your image quality ? or doesn't it matter with the animal side , excuse my ignorance.
With wildlife especially small birds we're constantly pushing the limits using high shutter speeds , small apertures (which is necessary to get the whole bird in focus) and never having quite enough reach
You have a choice:
- either use a crop sensor and fairly expensive lenses like EF100-400 ii or RF100-500 plus T.C.s
- or (if you're very rich) use FF and insanely expensive Great Whites like the EF600 f/4 plus T.C.s