Vintage Optics "Russentonne"

Bought this mirror optics called “Russentonne” with a focus length of 1000mm and a fix aperture of 10 on a flea market (for a handful euros). Because of collision with the flash mount you need to use a 2x tele converter to adapt it to a SL. It’s a misery that the converter adds chromatic aberrations to the system (that is originally free of it because of the mirrors), but you still get reasonables results, that can easiliy be optimized with some image dara processing filters…