I bought a Gene Davis 3x booster and tried it on two Weaver 36 power scopes and one Leupold 36x, for use in 600 meter groundhog matches. On a bench gun, we found it was clear at 100 and 200 meters, but beyond that, it was somewhat blurred. The oculars were adjusted according to directions, but image was better without the booster. I returned it for a full refund. BTW, Gene Davis is a good guy.