As a commenter has helpfully pointed out, one of the major differences between the A77 and competitors such as the Nikon D7000 and Canon 7D is that they have optical viewfinders, whereas the A77 will have an electronic viewfinder (EVF). At the moment Panasonic is also in the EVF camp with cameras such as the GH2 and G3, but Canon and Nikon are sticking firmly in the optical camp.
I think the matter of which is best very much comes down to personal preference and the type of photography you do. If I was mainly shooting things that move, and particularly if my living depended upon it, I would want an optical viewfinder, even more so if I wasn’t bothered about video. But I mainly shoot landscapes and also do some video, so an EVF has some strong potential advantages:
- I can see, and adjust, the actual exposure, which is of crucial importance for landscape work.
- I can see, and adjust, the colour balance, which is also of crucial importance for landscape work.
- I can shoot video whilst looking through the viewfinder and have some idea of what I’m getting. (…whilst at the same time not looking as if I’m shooting video, which can sometimes be helpful…)
If the A77 also has an articulated screen, which I hope it has, I also have the advantage that it becomes easier to compose and shoot with the camera in positions other than at head height, such as close to the ground or high above my head; I find shooting from head height always gives me the most boring shots.
Whether these things are advantages for you very much depend on what you are trying to do and your personal experiences. Certainly lots of people won’t move from optical viewfinders, and I won’t be criticising them. But I’ve pretty well decided I’m going to move to EVF.