The Sekonic L-358 Flash Master is a non-parallax spot viewfinder attachment that comes with a simple waterproof structure. The Sekonic Light Meter measures both ambient and flash lights.Based on the coverage angle (1, 5, and 10), the Sekonic NP Finder is classified under three typesIt measures light without parallax with its single-lens reflex methodMeasuring Range for Ambient: NPF 1° EV5~EV24.4    NPF 5° EV3~EV24.4    NPF 10° EV2~EV24.4Measuring Range for Flash: NPF 1° F8~F90.9     NPF 5° F2.8~F90.9     NPF 10° F2.8~F90.9