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 SX30 IS and Olympus E-P3 side-by-side from the front, back and top in their relative dimensions. Canon SX30 IS has external dimensions of 123 x 92 x 108 mm (4.84 x 3.62 x 4.25″) and weighs 601 g (1.32 lb / 21.20 oz) (including batteries). Olympus E-P3 has external dimensions of 122 x 69 x 34 mm (4.8 x 2.72 x 1.34″) and weighs 369 g (0.81 lb / 13.02 oz) (including batteries).
Below you can see the front view size comparison of Canon SX30 IS and Olympus E-P3. Olympus E-P3 is clearly the smaller of the two cameras. Its body is 1mm narrower, 23mm shorter and 74mm thinner than Canon SX30 IS. As you can tell, actually this is not a fair size comparison since Canon SX30 IS has a built-in lens but Olympus E-P3 doesn't. Once you put a lens on E-P3, 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.
Olympus E-P3 is significantly lighter (232g ) than the Canon SX30 IS 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 E-P3, the total kit will weigh much higher.
Unfortunately neither Canon PowerShot SX30 IS nor Olympus PEN E-P3 provides any type of weather sealing in their body, 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 Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Olympus E-P3's 3" LCD screen is slightly larger than Canon SX30 IS's 2.7" screen.
On the other hand, Canon SX30 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, Olympus E-P3 has a fixed type screen which provides almost no flexibility in shooting positions compared to SX30 IS.