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 Panasonic 3D1 and Olympus E-M1 side-by-side from the front, back and top in their relative dimensions. Panasonic 3D1 has external dimensions of 108 x 58 x 24 mm (4.25 x 2.28 x 0.94″) and weighs 193 g (0.43 lb / 6.81 oz) (including batteries). Olympus E-M1 has external dimensions of 130 x 94 x 63 mm (5.13 x 3.68 x 2.48″) and weighs 497 g (1.10 lb / 17.53 oz) (including batteries).
Below you can see the front-view size comparison of the Panasonic 3D1 and the Olympus E-M1. Panasonic 3D1 is clearly the smaller of the two cameras. Its body is 22mm narrower, 36mm shorter and 39mm thinner than Olympus E-M1. As you can tell, actually this is not a fair size comparison since Panasonic 3D1 has a built-in lens but Olympus E-M1 doesn't. Once you put a lens on E-M1, its thickness will increase significantly.
Here is the back view size comparison of the Panasonic 3D1 and Olympus E-M1.
Now lets look at the top view comparison of Panasonic 3D1 and Olympus E-M1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic 3D1 is significantly lighter (304g ) than the Olympus E-M1 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-M1, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the E-M1, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the 3D1.
LCD Screen Size and Features
Panasonic 3D1's 3.50" LCD screen is slightly larger than Olympus E-M1's 3 screen.