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 Leica TL and Panasonic FX580 side-by-side from the front, back and top in their relative dimensions. Leica TL has external dimensions of 134 x 69 x 33 mm (5.28 x 2.72 x 1.3″) and weighs 384 g (0.85 lb / 13.55 oz) (including batteries). Panasonic FX580 has external dimensions of 95 x 57 x 22 mm (3.74 x 2.24 x 0.87″) and weighs 167 g (0.37 lb / 5.89 oz) (including batteries).
Below you can see the front-view size comparison of the Leica TL and the Panasonic FX580. Panasonic FX580 is clearly the smaller of the two cameras. Its body is 39mm narrower, 12mm shorter and 11mm thinner than Leica TL. As you can tell, actually this is not a fair size comparison since Panasonic FX580 has a built-in lens but Leica TL doesn't. Once you put a lens on TL, its thickness will increase significantly.
Here is the back view size comparison of the Leica TL and Panasonic FX580.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic FX580 is significantly lighter (217g ) than the Leica TL 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 TL, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Leica TL nor Panasonic Lumix DMC-FX580 (Lumix DMC-FX550) 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 Mirrorless Cameras with Weather Sealing Top Compact Cameras with Weather Sealing
LCD Screen Size and Features
Leica TL's 3.70" LCD screen is slightly larger than Panasonic FX580's 3" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.