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 Sony A100 and Canon D30 side-by-side from the front, back and top in their relative dimensions. Sony A100 has external dimensions of 133 x 95 x 71 mm (5.24 x 3.74 x 2.8″) and weighs 638 g (1.41 lb / 22.50 oz) (including batteries). Canon D30 has external dimensions of 109 x 68 x 28 mm (4.29 x 2.68 x 1.1″) and weighs 218 g (0.48 lb / 7.69 oz) (including batteries).
Below you can see the front view size comparison of Sony A100 and Canon D30. Canon D30 is clearly the smaller of the two cameras. Its body is 24mm narrower, 27mm shorter and 43mm thinner than Sony A100. As you can tell, actually this is not a fair size comparison since Canon D30 has a built-in lens but Sony A100 doesn't. Once you put a lens on A100, 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 D30 is significantly lighter (420g ) than the Sony A100 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 A100, the total kit will weigh much higher.
LCD Screen Size and Features
Canon D30's 3" LCD screen is slightly larger than Sony A100's 2.5" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.