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 400D and Panasonic TS3 side-by-side from the front, back and top in their relative dimensions. Canon 400D has external dimensions of 127 x 94 x 65 mm (5 x 3.7 x 2.56″) and weighs 556 g (1.23 lb / 19.61 oz) (including batteries). Panasonic TS3 has external dimensions of 103 x 64 x 27 mm (4.06 x 2.52 x 1.06″) and weighs 197 g (0.43 lb / 6.95 oz) (including batteries).
Below you can see the front-view size comparison of the Canon 400D and the Panasonic TS3. Panasonic TS3 is clearly the smaller of the two cameras. Its body is 24mm narrower, 30mm shorter and 38mm thinner than Canon 400D. As you can tell, actually this is not a fair size comparison since Panasonic TS3 has a built-in lens but Canon 400D doesn't. Once you put a lens on 400D, its thickness will increase significantly.
Now lets look at the top view comparison of Canon 400D and Panasonic TS3.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic TS3 is significantly lighter (359g ) than the Canon 400D 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 400D, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the TS3, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the 400D.
LCD Screen Size and Features
Panasonic TS3's 2.70" LCD screen is slightly larger than Canon 400D's 2.5" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.