JJC RR-EOS Reverse Rings are threaded on one side to fit the filter thread of your lens. The other side has a mount like your camera lens. Screw the adapter into your lens' filter thread, turn the lens around and bayonet it into the camera body. This greatly increases the macro reproduction range capabilities.
Is it the good inversion ring for a Canon lens 50 mm f/1.8 STM?
Where can I buy it?
JJC: Dear customer, thank you for your interest about JJC product. This product works with Canon lens 50 mm f/1.8 STM.And we have send an email to you for more details of the product.