The Canon RF 50mm f/1.2L USM lens is one of the best Canon lenses ever. It's big and heavy compared to the EF version. It's also $2,300 new.
It also doesn't have image stabilization so one of Canon's R series bodies with in body stabilization is advisable. I don't own one of those bodies.
But, the lens is amazing and it's impossible not to be tempted to forgo some other, more flexible, options in order to enjoy the image quality of the f/1.2L. I would have to sell at least my 24-105mm and STM prime lenses and both EOS R bodies to get this lens and an EOS R6II, which has in body image stabilization.
One of the STM prime lenses I currently have is Canon's cheapest lens, the 50mm f/1.8 STM. The optical design for this lens is the same as the last three versions of the same lens in EF mount going back many decades. The images are very soft until f/4 where they become very nice. This lens is $126 new.
Yesterday morning I walked around with the 50mm STM lens to again fix the 50mm focal length in my mind. I used only f/4 so the images would be decent but still with some sense of a shallower depth of field.
In fact, I created a gallery to upload images as I occasionally use the cheap 50mm lens when I get tempted by the f/1.2L version. The gallery can be found at https://trulandphotography.com/50f4 and here are some of the first images.
UPDATE 5/13/23: I decided to sell my Canon RF STM prime lenses (35mm, 50mm and 85mm) and my two smaller Peak Design Sling bags. My new plan for when I want to play with a small sized setup is to adapt Minolta MD manual focus lenses. Back in the manual focus film days I used XG-M and then X700 bodies with a variety of Minolta and other MD mount lenses. I still have a 50mm MD Rokkor-X f/1.7 lens from the 1970s. I am awaiting an MD to RF adapter so I can use the lens with my EOS R bodies. If it works out like I hope I can then fill in with other inexpensive lenses as I come across them. Updates to follow.
Canon EOS R, RF 50mm f/1.8 STM, f/4, 1/2000 sec., ISO 100. Canon EOS R, RF 50mm f/1.8 STM, f/4, 1/1000 sec., ISO 100. Canon EOS R, RF 50mm f/1.8 STM, f/4, 1/3000 sec., ISO 100. Canon EOS R, RF 50mm f/1.8 STM, f/4, 1/1000 sec., ISO 100. Canon EOS R, RF 50mm f/1.8 STM, f/4, 1/750 sec., ISO 100. Canon EOS R, RF 50mm f/1.8 STM, f/4, 1/500 sec., ISO 100. Canon EOS R, RF 50mm f/1.8 STM, f/4, 1/2000 sec., ISO 100. Canon EOS R, RF 50mm f/1.8 STM, f/4, 1/250 sec., ISO 100.