The figure shows an empirical photometric scatter diagram from data obtained with the Graz BMK and a different CCD, without the C-filter, and at the original location near Graz, Austria (c/o Weingrill 2007, Master thesis, Univ. Graz). It shows that the system can deliver milli-mag photometry for stars brighter than 13 th mag in 120s integrations. 1%−5% photometry is possible down to a magnitude of 16 th mag. The latter limit could be extended by another magnitude with the new set up and longer exposure times. The system is never photon-noise limited though. Expected precision ranges are ≈1mmag for V<10 th mag, 2-3mmag for 10-11mag, ≈5mmag for 11-12.5mag, and ≈10mmag for 12.5-13.5mag. Faint limit is ≈16.5mag at ≈50mmag.