Optical properties of an axially symmetric black hole in the Rastall gravity Bakhtiyor Narzilloev, Ibrar Hussain, Ahmadjon Abdujabbarov and Bobomurat Ahmedov Eur. Phys. J. Plus, 137 5 (2022) 645 Published online: 30 May 2022 DOI: 10.1140/epjp/s13360-022-02872-8