  The hyperplane and proper time formalisms are discussed mainly for the
spin-half particles in the quantum case. A connection between these covariant
Hamiltonian formalisms is established. It is showed that choosing the
space-like hyperplanes instantaneously orthogonal to the direction of motion of
the particle the proper time formalism is retrieved on the mass shell. As a
consequence, the relation between the St\"uckelberg-Feynman picture and the
standard canonical picture of quantum field theory is clarified.
