Yes they do: Canon is the most used camera gear in astrophotography (see image on…
Thanks Alex for the photo.
At Photokina 2018 Samyang is showing off what appears to be the world’s widest lens for full frame DSLRs, the Samyang XP 10mm f/3.5. The image on top is showing the Canon EF mount version.
More images of the Samyang XP 10mm f/3.5 can be seen at ePhotozine.