If you use wide angle lenses, Sony's newest release in their full frame, mirrorless range for E-mount might be interesting to you. It certainly has its perks, but it's not without drawbacks.
Sony's new ultra-wide FE 12-24mm f/2.8 GM lens is catching a lot of photographers' attentions. If you've never shot at 12mm on a full frame body, you might be surprised just how wide it really is. I had to use a 12mm zoom lens similar to this on a job some years back, albeit on a Canon body, and once you get below 20mm, every extra millimeter you zoom out is substantial. For landscape, cityscape, and astrophotographers, Sony's lens that is releasing soon might be exactly what you're after. It does however, come with some drawbacks.
One of the key issues is shared with the lens I used that had a widest focal length of 12mm: a fixed lens hood to stop flaring and protect the inevitably bulbous front element. This prohibits the lens from using most filters (although if I remember correctly, there were systems in place for my lens which you circumnavigate this problem to some degree.) However, there is space at the back of the lens for a slide-in filter.
The bigger issue for me is the price. B&H currently lists this lens at $3,000 which is a staggering amount of money for a full frame lens. Yes, it's a fixed barrel length, f/2.8 through the focal ranges, and comes with the build quality we've come to enjoy with G Master lenses, but that's a lot of cheddar to drop on one lens. For $500 more, you can buy the incredible Sony a7R IV with an accessories kit! For me, I consider myself priced out of ever using this lens, which is a shame because it does seem like great glass.
What do you think of it?