A high-resolution focusing neutron diffraction arrangement optimized for strain/stress scanning has been tested on neutron diffractometer POLDI installed at the end of the thermal neutron guide of the medium resolution FRG-I reactor in GKSS Geesthacht. Basic properties of such an arrangement using the method of Bragg Diffraction Angle Analysis (BDAA) and exploiting Bragg diffraction optics are introduced. It is demonstrated that contrary to a widespread distrust, good luminosity of the strain scanner with a sufficiently high-resolution necessary for effective strain measurements can be done even though it is installed on the guide tube of the medium-power reactor.