Great introduction. Just the right level of details to pique my interest. I have used them but never really spent any time understanding them.
Be careful, if what you cook splatters, you can get stuff on the lens.
Also be careful with the focus, it does not take a very large focus circle to generate a lot of heat in a small area.
Great if you are making charcoal, not so great if you actually want to eat what you cook.