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 Sigma SD1 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). Sigma SD1 has external dimensions of 146 x 113 x 80 mm (5.75 x 4.45 x 3.15″) and weighs (including batteries).
Below you can see the front view size comparison of Canon SX20 IS and Sigma SD1. Canon SX20 IS is 18mm narrower and 25mm shorter than Sigma SD1 but it is also 7mm thicker. As you can tell, actually this is not a fair size comparison since Canon SX20 IS has a built-in lens but Sigma SD1 doesn't. Once you put a lens on SD1, 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.
Sigma SD1 is 600g lighter than the Canon SX20 IS but we don't think this will make a significant difference.
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 SD1, the total kit will weigh much higher.
Thanks to the weather sealed body of SD1, 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
Sigma SD1'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, Sigma SD1 has a fixed type screen which provides almost no flexibility in shooting positions compared to SX20 IS.