Please be cautious with inexpensive haedlamps on Amazon or Ebay that come with 18650 lithium batteries and chargers. The batteries are usually rewrapped recycled laptop batteries, the chargers might recharge them above 4.2v which is unsafe.
I had one whose light output and focusable beam was nice, but the included charger would go to 4.6v. Unfortunately the reflector portion got up and ran away when I was no looking. I liked the battery pack mounted on back of head to act as counterweight. The HC 50s beam was not adjustable, but the output pattern was greaat for what i use them for. The adjustable focus beams, for me, are mostly beneficial when one wants a lot more light distance 'throw' and wants a square of light thrown on a distant treetop or something. When focused for max throw, the shape of the light is the shape of the square LED emitter