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 Pentax K-5 and Panasonic ZS8 side-by-side from the front, back and top in their relative dimensions. Pentax K-5 has external dimensions of 131 x 97 x 73 mm (5.16 x 3.82 x 2.87″) and weighs 740 g (1.63 lb / 26.10 oz) (including batteries). Panasonic ZS8 has external dimensions of 105 x 58 x 33 mm (4.13 x 2.28 x 1.3″) and weighs 210 g (0.46 lb / 7.41 oz) (including batteries).
Below you can see the front-view size comparison of the Pentax K-5 and the Panasonic ZS8. Panasonic ZS8 is clearly the smaller of the two cameras. Its body is 26mm narrower, 39mm shorter and 40mm thinner than Pentax K-5. As you can tell, actually this is not a fair size comparison since Panasonic ZS8 has a built-in lens but Pentax K-5 doesn't. Once you put a lens on K-5, its thickness will increase significantly.
Here is the back view size comparison of the Pentax K-5 and Panasonic ZS8.
Now lets look at the top view comparison of Pentax K-5 and Panasonic ZS8.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic ZS8 is significantly lighter (530g ) than the Pentax K-5 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 K-5, the total kit will weigh much higher.
Weather Sealing
With its weather-sealed body, we believe that the K-5 has a big advantage over the ZS8 which doesn't provide any kind of environmental sealing.
LCD Screen Size and Features
Pentax K-5 and Panasonic ZS8's LCD screens have the same diagonal size of 3.00 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.