In a repeat episode of one of the survival shows, I fell off my chair when Bear or one of the others tried to use a magnifying glass to start a fire ( without a char cloth) 45 minutes later - well they got a smoke... It can't be that hard! Today I came across old relatives plastic magnify glass and a poor one at that... maybe 3x and four inches across and for the Gram weenies - 2oz. Outside its sunny at 39 degrees and light wind and the sun is less than 40 degrees from the horizon (low). I grabbed and held the char cloth and in seconds it was smoking and that's important - This means (DO NOT STOP) 20 seconds later I had fire and burning fingers.
You can put the tin on an alcohol burner, you do not need a grill.
This guy stopped and it took longer ... but you get the idea
Even a better video started fire from a compass
I hope you enjoyed that, it simply a good skill to know, if you get a chance practice. In camp you can amaze your friends with your new skill.