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If my grin was any bigger it would be illegal, Like Hunter S. Thompson on speed!
So I don't have a range finder but was able to use my bicycle trip meter to measure out a tenth of a mile and .15 and .2 of a mile. At .10 the W10 lit up a twenty foot tree really nicely. My Emisar D4S with SST-20 6500K: 4200lm / 58,000cd lit up three trees at that distance nicely but less brightly plus everything in between. Across a lake here, trees were lit up a bit but it was too far away for me to see with unaided eyes. I took a photo, with my phone at 7.9x digital zoom @ .10 mi. but it's not worth posting. I can use this light for lighting up house address at night and the size of it guaranties I'll never leave it behind. I like it!