Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Canon SX120 IS and Nikon D3S side-by-side from the front, back and top in their relative dimensions. Canon SX120 IS has external dimensions of 111 x 71 x 45 mm (4.37 x 2.8 x 1.77″) and weighs 285 g (0.63 lb / 10.05 oz) (including batteries). Nikon D3S has external dimensions of 160 x 157 x 88 mm (6.3 x 6.18 x 3.46″) and weighs 1240 g (2.73 lb / 43.74 oz) (including batteries).
Below you can see the front view size comparison of Canon SX120 IS and Nikon D3S. Canon SX120 IS is clearly the smaller of the two cameras. Its body is 49mm narrower, 86mm shorter and 43mm thinner than Nikon D3S. As you can tell, actually this is not a fair size comparison since Canon SX120 IS has a built-in lens but Nikon D3S doesn't. Once you put a lens on D3S, its thickness will increase significantly.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Canon SX120 IS is significantly lighter (955g ) than the Nikon D3S which may become a big advantage especially on long walking trips.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on D3S, the total kit will weigh much higher.
Thanks to the weather sealed body of D3S, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to SX120 IS.
LCD Screen Size and Features
Canon SX120 IS and Nikon D3S's LCD screens has the same diagonal size of 3".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.