ThomX is a novel compact X-ray light source, utilising a laser and 50 MeV electron storage ring to produce X-ray photons via Compton scattering. Screens, observed by zoom lenses and optical cameras, can be used to monitor the transverse beam profile at various points. An issue with the implementation of this system is that after adjusting the zoom one needs to recalibrate the the optical system, measuring the resolution of the optical system and deducing the transformation from pixel space observed on the camera to geometrical space in the laboratory. To calibrate and measure the resolution limit of the cameras a USAF 1951 resolution chart that can be moved into or out of the screen position is used. We will report on and demonstrate the use of open source computer vision libraries to compute this calibration, and the affine transformation between the camera image plane and the screens can be deduced. We will also comment on how consumer available Canon EF mount lenses may be used as a remote controllable optical system.