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 SX20 IS and Nikon D3S side-by-side from the front, back and top in their relative dimensions. Canon SX20 IS has external dimensions of 128 x 88 x 87 mm (5.04 x 3.46 x 3.43″) and weighs 600 g (1.32 lb / 21.16 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 SX20 IS and Nikon D3S. Canon SX20 IS is clearly the smaller of the two cameras. Its body is 32mm narrower, 69mm shorter and 1mm thinner than Nikon D3S. As you can tell, actually this is not a fair size comparison since Canon SX20 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 SX20 IS is significantly lighter (640g ) 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 SX20 IS.
LCD Screen Size and Features
Nikon D3S's 3" LCD screen is slightly larger than Canon SX20 IS's 2.5" screen.
On the other hand, Canon SX20 IS sports a Fully Articulated screen
which you can change the angle and position of the screen almost freely, making it possible to shoot from waist or over the head levels, and especially very useful for shooting selfies and video. On the other hand, Nikon D3S has a fixed type screen which provides almost no flexibility in shooting positions compared to SX20 IS.