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Is your telephoto lens this one?:
If so, that has an EOS mount, and will work OK with (for instance) a Canon EOS 5D Mark III (though those cameras are not new by now, probably only available used).
As to autofocus (AF) please Note: It has an AF Pause or AF Stop mode... four AF Stop Buttons located on the front grip ring, allow you to temporarily pause AutoFocusing. So it can be interrupted... but AutoFocus should work with any Canon EOS camera, I should think, provided you have not tripped any of those four buttons.
This telephoto lens has an EF Mount. Non-EF-mount cameras, it will not be mountable upon.
Other cameras it will work with, are any Canon EF-mount, full-frame and APS-C, DSLR digital cameras. Such as the Canon EOS T7i, and the Canon 80D:
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