Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Panasonic ZS3 and Pentax Q7 side-by-side from the front, back and top in their relative dimensions. Panasonic ZS3 has external dimensions of 103 x 60 x 33 mm (4.06 x 2.36 x 1.3″) and weighs 229 g (0.50 lb / 8.08 oz) (including batteries). Pentax Q7 has external dimensions of 102 x 58 x 34 mm (4.02 x 2.28 x 1.34″) and weighs 200 g (0.44 lb / 7.05 oz) (including batteries).
Below you can see the front view size comparison of Panasonic ZS3 and Pentax Q7. Pentax Q7 is 1mm narrower and 2mm shorter than Panasonic ZS3 but it is also 1mm thicker. As you can tell, actually this is not a fair size comparison since Panasonic ZS3 has a built-in lens but Pentax Q7 doesn't. Once you put a lens on Q7, its thickness will increase significantly.
Here is the back view size comparison of Panasonic ZS3 and Pentax Q7.
Now lets look at the top view comparison of Panasonic ZS3 and Pentax Q7.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Pentax Q7 is 29g lighter than the Panasonic ZS3 but we don't think this will make a significant difference.
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 Q7, the total kit will weigh much higher.
Unfortunately neither Panasonic Lumix DMC-ZS3 (Lumix DMC-TZ7) nor Pentax Q7 provides any type of weather sealing in their body, 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
Panasonic ZS3 and Pentax Q7's LCD screens has the same diagonal size of 3".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.