To my opinion at the photo there is a russian rank and file soldier, cavalryman, in the uniform generally of the period of the tzar Alexander III (1881-1894). Theoretically it may be also the uniform of a russian policeman/ mounted gendarme of the same period. In the last case (even if he was a Jew) he obviously should have been baptized (to russian Orthodox) in other case I am not sure that it should be possible for a Jew to serve in russian police/gendarmeria.
