I think it is somewhat earlier than 1911. The chaps are all wearing non blackened sword scabbards and those that are visible are wearing two sling loops attached to the scabbards. Should therefore be pre 26 June 1905. Assuming this is the case and the photo dates from the early 1900s, I would say this photograph shows the adjutants of the Garde-Kavallerie-Division around 1902. Note the large medal bar of the Garde-Ulan adjutant. He is most probably Rittmeister Constantin Graf von Beroldingen, the divisional adjutant with the uniform of 2. GUR.
Regards
Glenn