I'm not new to Landscape shooting. I am just new to Sony and the lens choices. I've done a bit of research and I just want to get some feedback from others as to what they have chosen.
.... What is the opinion on using an adapter with the Canon lens?
I use a Metabones adaptor on the Sony A7R and A7RII.
With up-to-date firmware updates the experience is almost as good as a Canon body - Canon lens combination. However the autofocus abilities are not that crucial for landscape work.
Battery life is another potential con, but not really an issue for landscape work. If you need to - buy a battery grip and have at least four batteries (two to use and two to charge).
Frankly, if the Canon lens is a good one then the IQ is extraordinary. Like Eric, I use anything from ultra wide to 400mm for landscape work. I do have two very good Sony lenses but most of my lens line-up is Canon. All lenses are used interchangeably according to need.
I love shooting in low light, and or, high contrast situations and the A7R and A7RII absolutely shine in these scenarios. Obviously, tripods and remote releases really allow one to maximise IQ.
In summary, using the A7R or A7RII mated with Canon lenses via a Metabones adaptor can deliver images, as good, if not better, than any other imagine system available.
Tony Jay