Very wide/fisheye lens RF for R5/R3 system from Canon?

[puffo25]

Hi all. I am looking for a very wide and bright lens (ie F/1,8) for my R5 full frame camera.
I do astro and landscape photo and sometimes I need a wide lens.
Currently I have the RF 15-35mm f2.8 which is of course great BUT in some occasions, a brighter and wider lens will be very much welcome.
Sadly the old (and still good) EF 8-15mm Canon fish eye does NOT cover properly the full frame of my R5 as it works better with a different sensor...

Why canon so far has NOT put in their production calendar a wide lens?

 

[neuroanatomist]

Sadly the old (and still good) EF 8-15mm Canon fish eye does NOT cover properly the full frame of my R5 as it works better with a different sensor...

It should work on your R5 as on any FF camera – circular fisheye at 8mm, full-frame fisheye at 15mm. Is it not doing that?

 

[puffo25]

Hi, the 8mm aperture on a FF Canon R5 does not look like a native 8mm fisheye lens due to some sensor crop.
Also this old but sharp lens is only F/4 while for astro (and a bit of landscape), I do need a much more bright lens, something btw F1,8 and 2,0 if possible....