  Uncertainties in successive measurements of general canonically conjugate
variables are examined. Such operators are approached within a limiting
procedure of the Pegg-Barnett type. Dealing with unbounded observables, we
should take into account a finiteness of detector resolution. An appropriate
reformulation of two scenarios of successive measurements is proposed and
motivated. Uncertainties are characterized by means of generalized entropies of
both the R\'{e}nyi and Tsallis types. The R\'{e}nyi and Tsallis formulations of
uncertainty relations are obtained for both the scenarios of successive
measurements of canonically conjugate operators. Entropic uncertainty relations
for the case of position and momentum are separately discussed.

Quantum Physics