He is seen here as an SNCO of the Reichswehr.
Rank - as shown on the shoulder boards - is Feldwebel; his NCO status is also displayed be the collar braid [Tresse].
Branch color [Waffenfarbe] as shown in the central stripes on the collar patches and the shoulder board piping appears quite dark; it could be black for Engineers [Pioniere].
Below his left breast pocket is the German Riding Badge [Deutsches Reitabzeichen]; the stripes on his left lower sleeve are shooting badges [Schie▀auszeichnungen].
From the uniform, badges and insignia, I would date the photograph to the 1930 - 1934 period.
A very nice portrait, by the way.
Just for reference I show a rank chart for the "Friedensheer", the forerunner of the Reichswehr in 1919...he may well of worn some of this insignia......1) Private. 2) Private first class.3) Unteroffizier. 4) Sergeant. 5) Vizefeldwebel. 6) Feldwebel. 7) Unteroffizier after 4/2/1919. 8) Leutnant. 9) Oberleutnant. 10) Hauptmann. 11) Major. 12) Oberstleutnant. 13) Oberst. 14) Brigadegeneral 15) Generalmajor. 16) Generalleutnant. 17) General der Infantrie/Artillerie etc....
"The German Army is the perfectly adapted, perfectly running Machine. The difference is that the Germans are organised with a view to War...with the cold, hard, practical and business-like purpose of winning victories."
G.W. Steevens - The Daily Mail (1897)