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 Casio EX-ZR300 and Panasonic G3 side-by-side from the front, back and top in their relative dimensions. Casio EX-ZR300 has external dimensions of 105 x 59 x 29 mm (4.13 x 2.32 x 1.14″) and weighs 205 g (0.45 lb / 7.23 oz) (including batteries). Panasonic G3 has external dimensions of 115 x 84 x 47 mm (4.53 x 3.31 x 1.85″) and weighs 336 g (0.74 lb / 11.85 oz) (including batteries).
Below you can see the front-view size comparison of the Casio EX-ZR300 and the Panasonic G3. Casio EX-ZR300 is clearly the smaller of the two cameras. Its body is 10mm narrower, 25mm shorter and 18mm thinner than Panasonic G3. As you can tell, actually this is not a fair size comparison since Casio EX-ZR300 has a built-in lens but Panasonic G3 doesn't. Once you put a lens on G3, its thickness will increase significantly.
Here is the back view size comparison of the Casio EX-ZR300 and Panasonic G3.
Now lets look at the top view comparison of Casio EX-ZR300 and Panasonic G3.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Casio EX-ZR300 is significantly lighter (131g ) than the Panasonic G3 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 G3, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Casio Exilim EX-ZR300 nor Panasonic Lumix DMC-G3 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 Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Casio EX-ZR300 and Panasonic G3's LCD screens have the same diagonal size of 3.00 inches.
On the other hand, Panasonic G3 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. Casio EX-ZR300's LCD screen is a fixed type which provides almost no flexibility in shooting positions compared to G3.