Straight Compact Features Easy to carry for use birding at the shooting range or in general observation the 15-40x50 Compact Spotting Scope from Barska is under 10 long but has the features you need to see distant details. Fully coated glass and a BK7 Porro prism transmit bright contrast-rich images throughout the entire zoom range. Its field of view is a generous 150 Straight Compact Specifications BK7 Porro Prism Fully Coated Optics 150 Field of View at 15x Mini Tabletop Tripod