Vortex Razor UHD 10x50 BinocularThe Vortex Razor UHD 10x50 Binoculars are a good option when you need excellent low light performance in the upper mid price range. The 50mm objective lenses gather nearly 42% more light than 42mm objectives and the phase corrected Abbe Koenig prisms help to transmit a higher percentage of the incoming light to your eyes because they have only 3 reflective faces rather than the 5 faces with the more common Schmidt Pechan prisms. Vortex's APO System