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 Canon 1D C and Canon 5D MIII side-by-side from the front, back and top in their relative dimensions. Canon 1D C has external dimensions of 158 x 164 x 83 mm (6.22 x 6.46 x 3.27″) and weighs 1500 g (including batteries). Canon 5D MIII has external dimensions of 152 x 116 x 76 mm (5.98 x 4.57 x 2.99″) and weighs 950 g (2.09 lb / 33.51 oz) (including batteries).
Below you can see the front-view size comparison of the Canon 1D C and the Canon 5D MIII. Canon 5D MIII is clearly the smaller of the two cameras. Its body is 6mm narrower, 48mm shorter and 7mm thinner than Canon 1D C.
Here is the back view size comparison of the Canon 1D C and Canon 5D MIII.
Now lets look at the top view comparison of Canon 1D C and Canon 5D MIII.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Canon 5D MIII is significantly lighter (550g ) than the Canon 1D C 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 both Canon 1D C and Canon 5D MIII have the same Canon EF lens mount and Full frame sized sensors, lenses will not be a differentiator on total size of the system.
Weather Sealing
Both the 1D C and the 5D MIII have weather sealings in their bodies, making them resistant to water and dust.
LCD Screen Size and Features
Canon 1D C and Canon 5D MIII's LCD screens have the same diagonal size of 3.20 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.