A quick look at several precision scopes with 50mm (or close to it) objectives: March 3-24x52, Tangent Theta TT315M 3-15x50, Nightforce NX8 2.5-20x50, Crimson Trace 5-series 3-18x50, Brownells MPO 3-18x50, EOTech Vudu 5-25x50