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 1Ds MIII and Canon IXUS 165 side-by-side from the front, back and top in their relative dimensions. Canon 1Ds MIII has external dimensions of 150 x 160 x 80 mm (5.91 x 6.3 x 3.15″) and weighs 1385 g (3.05 lb / 48.85 oz) (including batteries). Canon IXUS 165 has external dimensions of 95 x 54 x 22 mm (3.74 x 2.13 x 0.87″) and weighs 128 g (0.28 lb / 4.52 oz) (including batteries).
Below you can see the front-view size comparison of the Canon 1Ds MIII and the Canon IXUS 165. Canon IXUS 165 is clearly the smaller of the two cameras. Its body is 55mm narrower, 106mm shorter and 58mm thinner than Canon 1Ds MIII. As you can tell, actually this is not a fair size comparison since Canon IXUS 165 has a built-in lens but Canon 1Ds MIII doesn't. Once you put a lens on 1Ds MIII, its thickness will increase significantly.
Here is the back view size comparison of the Canon 1Ds MIII and Canon IXUS 165.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Canon IXUS 165 is significantly lighter (1257g ) than the Canon 1Ds MIII 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 1Ds MIII, the total kit will weigh much higher.
Weather Sealing
With its weather-sealed body, we believe that the 1Ds MIII has a big advantage over the IXUS 165 which doesn't provide any kind of environmental sealing.
LCD Screen Size and Features
Canon 1Ds MIII's 3.00" LCD screen is slightly larger than Canon IXUS 165's 2.7 screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.