fwiw i used to carry a 3 inch magnifying lens around when i was a kid growing up in Northern British Columbia. on my summer bush walks i could usually start a fire with the thing in about 15 seconds, and i had wood burn decorations on almost everything i carried. mind you the elevation was about 3000 feet so i reckon the sun was probably fairly strong, perhaps also the cause of the countless sunburns i got. humidity was bugger all too so that probably helped. pine and spruce forests if anyone is asking.
anyway, in a moment of misguided research i once decided to test the thing on the back of my arm. i can confirm that yes indeed, there was plenty of heat in that little pencil dot of light. that took a while to heal.
anyway, in a moment of misguided research i once decided to test the thing on the back of my arm. i can confirm that yes indeed, there was plenty of heat in that little pencil dot of light. that took a while to heal.
Last edited: