We tested a dozen signal mirrors over a 22-mile range today.

We'd used this range before, but not tested a 2"x3" glass mirror, so we made sure to test one this time.

My tester found the Coghlan's 2"x3" glass mirror and the Rescue Flash easiest to use.

To get a feel for the number of flashes, I recommend these be played back in full screen (use the icon at the bottom right of the frame at YouTube) and 720HD quality (use the "gear" icon at the bottom of the frame).

Note that the camera sees many more flashes than I call out with my naked eye (it is an 18x telephoto - comparable sensitivity to my eye with 7x50 binoculars).

Arranged in descending brightness (not all mirrors posted to YouTube)

22 mile flash from 12"x12" glass mirror
(1too big for backpacking, but darn bright!)

22 mile flash from 3"x5" glass signal mirror

22 mile flash from 2"x3" glass signal mirror

22 mile Sun Flash from 2"x3" Plastic Signal Mirror

22 mile Sun Flash from 2"x3" metal mirror
(needed binoculars to see it)

One geeky technical note - to provide a target
visible at 22 miles to sight to, I used a
British World War II heliograph with 5" diameter mirror:
A signal mirror should backup a radio distress signal, like a 406 MHz PLB (ACR PLB) (Ocean Signal PLB)