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 ELPH 520 HS and Canon 10D side-by-side from the front, back and top in their relative dimensions. Canon ELPH 520 HS has external dimensions of 87 x 54 x 19 mm (3.43 x 2.13 x 0.75″) and weighs 155 g (0.34 lb / 5.47 oz) (including batteries). Canon 10D has external dimensions of 150 x 107 x 75 mm (5.91 x 4.21 x 2.95″) and weighs 875 g (1.93 lb / 30.86 oz) (including batteries).
Below you can see the front-view size comparison of the Canon ELPH 520 HS and the Canon 10D. Canon ELPH 520 HS is clearly the smaller of the two cameras. Its body is 63mm narrower, 53mm shorter and 56mm thinner than Canon 10D. As you can tell, actually this is not a fair size comparison since Canon ELPH 520 HS has a built-in lens but Canon 10D doesn't. Once you put a lens on 10D, 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 ELPH 520 HS is significantly lighter (720g ) than the Canon 10D 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 10D, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Canon ELPH 520 HS (IXUS 500 HS) nor Canon EOS 10D 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 Compact Cameras with Weather Sealing Top DSLR Cameras with Weather Sealing
LCD Screen Size and Features
Canon ELPH 520 HS's 3.00" LCD screen is slightly larger than Canon 10D's 1.8" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.