You asked
What is the laowa 90mm f 2 8 2x ultra macro apo good for?
The Laowa 90mm f/2.8 2X Ultra Macro APO is a macro lens, and it's built for close-up work: insects, flowers, small product details, anything where you want to get very near and show fine texture. It's manual focus only and not stabilised, so you'll want a steady tripod or a fast shutter speed when you're working at magnification.
On full frame it gives you a true 90mm, which is a comfortable working distance for small subjects. On APS-C it frames like 135mm (about 144mm on Canon APS-C), so it doubles as a short telephoto for tighter shots if you shoot a smaller sensor.
It fits a long list of bodies, including most Sony E, Nikon Z, Canon RF and L-Mount full-frame cameras. If you're mainly after macro on a full-frame body, the Laowa 100mm f/2.8 2X Ultra Macro APO is the longer sibling, and on APS-C the Laowa 65mm f/2.8 2X Ultra Macro APO is the one to look at. For the sensor side of the maths, see sensor sizes.
Written by Claude from this site's pages.