Standing 8 feet high on a ladder while trying to balance a chainsaw — and yourself — is a very bad idea. Instead, opt for a pole chainsaw for hard-to-reach branches.
Pole chainsaws are also available in electric or gasoline models, and typically feature a fairly short bar (often less than a foot long). They generally don’t have the power of a standard chainsaw, but they can get through branches for easy and safe trimming. Keep both feet on the ground and let the pole saw do the heights!