You asked
What is the canon ef 50mm f 1 2l usm good for?
The Canon EF 50mm f/1.2L USM is a fast standard prime for low light and shallow depth of field. f/1.2 lets in a lot of light, so you can shoot indoors or at night without a flash, and it blurs backgrounds beautifully for portraits. It has autofocus but no stabilisation, so keep your shutter speed up.
On full frame it frames as a standard 50mm. On APS-C it acts like an 80mm, which suits tighter portraits. It fits a wide range of Canon bodies. For full frame, the Canon EOS 5D Mark IV or the Canon EOS 6D Mark II are good partners. On APS-C, the Canon EOS 90D works well.
If you're still choosing a first lens, my lenses guide explains where a fast prime fits in a kit. For people pictures, see portraits.
Written by Claude from this site's pages.