I own an EOS R5 and I do mainly landscape and astro (Milky Way and so on....).
I use the RF 15-35 f2,8 with the MSM rotator star tracker but indeed a faster/brighter lens would be a bonus.
In my photography sometimes I also would like to use a wider fish-eye lens, for dramatic images so now my major question is what would be the most obvious choice: the RF 14mm f1.4 or the RF 7-14 f2.8 considering the fact that I have already the RF 15-35 f2,8? In terms of wider images, is the new RF 14mm f/1.4 making the images much wider compared to the RF 15-35 f2,8? The faster lens is of course handy BUT at the end it is a bit more important to me to use a wider lens rather than a brighter lens, since astro is NOT my only photo genre????