Dirtydave asked:
The flashlight i have moves in and out of focus as i twist the cap. The light gradually gets more and then less condensed. Is there any way i can find the focal length of the lens in it?
Camp Stoves
The flashlight i have moves in and out of focus as i twist the cap. The light gradually gets more and then less condensed. Is there any way i can find the focal length of the lens in it?
Camp Stoves
How do i find the induced current made from a hand crank flashlight?
North Face Sale
February 28th, 2010
Car Auctions
If you can take off the lens completely:
Remove lens.
Hold it up and try to focus a distant light source on a wall. I usually use light coming in a window. Alternatively, try and focus a ceiling light on to the floor. As long as the source is a few metres away, this will give you a pretty good answer for the focal length.