Canon RF 50mm f/1.8 STMCanon RF 50mm f 1. 8 STM Canon SKU: 4515C002 Helix SKU: CA4515C002 Overview RF 50mm F1. 8 STM Some items like your keys or wallet you just take everywhere you go because you just never know. For anyone with an EOS R series camera, add the RF50mm F1. 8 STM lens to that list. As part of the EOS R System, it's nice and compact thanks to its RF mount so you can shoot and get a great shot anywhere and anytime. Size isn't all though. As a fixed focal length