Size and weight are big decision factors when you are trying to find the ideal camera for your needs.
In this section, we are going to illustrate the Nikon D6 and Sony A77 side-by-side from the front, back and top in their relative dimensions. Nikon D6 has external dimensions of 160 x 163 x 92 mm (6.3 x 6.42 x 3.62″) and weighs 1270 g (2.80 lb / 44.80 oz) (including batteries). Sony A77 has external dimensions of 143 x 104 x 81 mm (5.63 x 4.09 x 3.19″) and weighs 732 g (1.61 lb / 25.82 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon D6 and the Sony A77. Sony A77 is clearly the smaller of the two cameras. Its body is 17mm narrower, 59mm shorter and 11mm thinner than Nikon D6.
Now lets look at the top view comparison of Nikon D6 and Sony A77.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony A77 is significantly lighter (538g ) than the Nikon D6 which may become a big advantage especially on long walking trips.
Also keep in mind that body weight is not the only deciding factor when comparing two interchangeable camera bodies, you also have to take into account the lenses that you will be using with these bodies. Since Nikon D6 has a Full frame sensor and Sony A77 has a smaller APS-C sensor, Sony A77's lenses for a similar focal length and aperture will generally be lighter and smaller than the Nikon D6 lenses.
Weather Sealing
Both the D6 and the A77 have weather sealings in their bodies, making them resistant to water and dust.
LCD Screen Size and Features
Nikon D6's 3.20" LCD screen is slightly larger than Sony A77's 3 screen.