Mirror lens? Don't bother. | Martin Pinnau Photography
White 500mm F6.3 Manual Fixed Focus Telephoto Mirror Lens + T2 Mount Adapter Ring For Canon Nikon Pentax Sony Dslr Cameras - Camera Lenses - AliExpress
A bit of history about Canon and catadioptric (mirror) lenses
Manual 500mm F8 Telephoto Mirror Lens With T2-eos Adapter Ring For Canon 80d 77d 70d 60d 7d 5d Mark Ii 750d 700d 650d 1200d 100d - Camera Lenses - AliExpress
Canon Camera Mirror Lenses | Telephoto Lens Sony Mount | Mirror Lens Camera 500mm - Camera Lenses - Aliexpress
Opteka 500mm f/6.3 (with 2x- 1000mm) Telephoto Mirror Lens for Canon EOS RF-Mount R6, R5, Ra, RP and R Mirrorless Digital Cameras - Walmart.com
Sigma Multi Coated 600mm F/8 Macro Mirror Lens for Canon Film - Etsy Israel
Canon EOS R5 Mirrorless Digital Camera (R5 Camera Body) B&H Photo