This video was inspired by my taking issue with the 2nd to last figure in John McCann's excellent article, "Signal Mirrors for Rescue", at www.survivalresources.com/signal-mirrors-for-rescue.html John and I both recommend getting a mirror with a retroreflective (reflex) sight ( it is a LOT easier to reliably hit your target with a reflex sight). However, if you don't have one handy, or the sun to target angle is greater than about 135º, you'll need to use an alternate aiming method, like the "Vee-Finger" method covered in John's article and shown second here. If the sun is behind you, your head may block the light with any type of signal mirror unless you tilt your head really far back, lay on your back, or use a second mirror to reflect the light back to you. John's 2nd to last figure, and this video, cover the "lay on your back" option. My video is a (roughly edited) tutorial on using a signal mirror while lying on your back, and why you don't want to hold the mirror away from the line between your eye and the target, despite John's 2nd to last figure (and in a similar figure in the 1985 USAF survival manual). Those figures are contrary to John's instructions in the text of his article to: "Keep your eye, signal mirror and your outstretched fingers in a straight line", so I don't understand why John's diagram doesn't match his text. I offered to make a video showing my approach, and this is it. I contend the mirror should be held with one edge next to the line from your eye to the target when using the "Vee-finger" method, and I also contend that, to flash accurately at long distance using the "Vee-finger" method, you need to be more precise than simply putting the target midway between your fingers, and I describe and demonstrate my technique. (Note: since the camera is close to, but NOT in line with my eye, what you see is not what I see - I see the target midway between the two corners of the rectangle of light on my fingers that correspond to the corners of the edge of the mirror closest to the line from my eye to the target. Also note that the apparent width (angular width) of the reflected rectangle of light on the ceiling is much less than it appears on my fingers. At long range, the apparent width of the beam is even narrower, about 0.54º, or about 1/3 the width of one of my "Vee-fingers" - it is the apparent diameter of the full moon, or of LIncoln's head on a penny held at arm's length. This "narrower than you think" beam is the reason that precise alignment of the "Vee-Finger" method is important at long range. Yes - at close range people will see the flash even if you don't hit them with the main beam, because there is a "glow" due to mirror irregularities that is wider than the main beam, but if your rescuers are beyond shouting range (and if they are in shouting range, try shouting) your flash will be FAR more noticable if you hit them with that (very narrow, and EXTREMELY bright) main beam. The Boy Scouts and I have successfully signaled each other many times at 20+ mile range using 2"x3" glass signal mirrors.