Hello,
A photo of a Fokker E.III E.226/16 flown by Oswald Boelcke is currently available on ebay at:
https://www.ebay.de/itm/161-Foto-BEL...wAAOSwYY1eVsiO
Since initially posting this link I've received information offboard suggesting the serial is more likely E.245/16 and that the aircraft very possibly did not belong to Boelcke, but may come from FFA 9b.
Regards,
Clint