Bailey, I smoked a bowl the other day from start to finish lit only with my lens. The tobacco smokes instantly as soon as you focus the point of light. I would almost say quicker and less trouble than messing with matches. The intensity is controlled by the distance between the object you want to burn and the lens itself. Raising the lens away from the object the circle of light will get bigger and also less hot. Bring it down to a pinpoint and it's like a laser. That distance is usually about 6 or 7 seven inches.
One thing I have noticed is that I suspect the light beam is super hot becuase it temporarily imparts a different, maybe a more burnt taste to my tobacco that is not present when I use a wood match or lighter to light. (There is some other discussions going on about how do you light and temperatures of flames etc.) So while it's a cool parlor trick so to speak it's not something I'll do too often. But as stated for an emergency back up for the tacklebox or out on the links its much better than no smoke!