Parabolic mirror spotlight DIY

[Aston]

Hi all, fascinated by the anti aircraft search lights I'm hoping to build a tiny budget searchlight, my parabolic mirror is a satellite dish covered in mirror vinyl wrap, my bulb so far is a 2000W halogen bulb from the theatre/stage, my first question is where to put the bulb in regards to getting the best beam, so any mathematicians out there ,,,
Parabolic dimensions
Height, 32" (810mm)
Width, 28 and a half (725mm)
Depth 2.756 inches (70mm)
Maybe this will help regarding the formula...
https://www.quora.com/A-spotlight-w...b-be-located-so-as-to-produce-a-beam-of-light

Thank you