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 SX10 IS and Canon 450D side-by-side from the front, back and top in their relative dimensions. Canon SX10 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). Canon 450D has external dimensions of 129 x 98 x 62 mm (5.08 x 3.86 x 2.44″) and weighs 524 g (1.16 lb / 18.48 oz) (including batteries).
Below you can see the front-view size comparison of the Canon SX10 IS and the Canon 450D. Canon SX10 IS is 1mm narrower and 10mm shorter than Canon 450D but it is also 25mm thicker. As you can tell, actually this is not a fair size comparison since Canon SX10 IS has a built-in lens but Canon 450D doesn't. Once you put a lens on 450D, 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 450D is 76g lighter than the Canon SX10 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 450D, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Canon PowerShot SX10 IS nor Canon EOS 450D (EOS Rebel XSi / EOS Kiss X2) provides any type of weather sealing in their bodies, so you have to give extra care especially when you are shooting outdoors. If weather sealing is a must-have feature for you, check these sections: Top Bridge Cameras with Weather Sealing Top DSLR Cameras with Weather Sealing
LCD Screen Size and Features
Canon 450D's 3.00" LCD screen is slightly larger than Canon SX10 IS's 2.5" screen.
On the other hand, Canon SX10 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, Canon 450D has a fixed type screen which provides almost no flexibility in shooting positions compared to SX10 IS.