No information available.
This photo was in the album next to the photo of "Rudolf". On the back is written: Gewidmet von eurem Hinrich Boekhoff (translation: dedicated by/from your Hinrich Boekhoff). The date is 29 Mar 1940.
A site visitor reports: My uncle Hinrich Boekhoff was reported missing in the Second World War in March 1944. I do not know whether the man on your photo is him but the appearance looks similar to other family members.