I have 2 Swarovski scopes with 1” tube. One has a 42 mm obj. lens and the other has a 50 mm obj. lens. I tested them both this fall set at 6x for low light conditions and to be honest really couldn’t tell much difference between the two. They both worked well beyond legal light conditions. I’m not sure how the 56 mm would work but I really see no need to go larger then 42 mm with top end scopes when hunting big game. Just my opinion...