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 Olympus TG-870 and Pentax K-7 side-by-side from the front, back and top in their relative dimensions. Olympus TG-870 has external dimensions of 113 x 64 x 28 mm (4.45 x 2.52 x 1.1″) and weighs 221 g (0.49 lb / 7.80 oz) (including batteries). Pentax K-7 has external dimensions of 131 x 97 x 73 mm (5.16 x 3.82 x 2.87″) and weighs 750 g (1.65 lb / 26.46 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus TG-870 and the Pentax K-7. Olympus TG-870 is clearly the smaller of the two cameras. Its body is 18mm narrower, 33mm shorter and 45mm thinner than Pentax K-7. As you can tell, actually this is not a fair size comparison since Olympus TG-870 has a built-in lens but Pentax K-7 doesn't. Once you put a lens on K-7, its thickness will increase significantly.
Here is the back view size comparison of the Olympus TG-870 and Pentax K-7.
Now lets look at the top view comparison of Olympus TG-870 and Pentax K-7.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Olympus TG-870 is significantly lighter (529g ) than the Pentax K-7 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-7, the total kit will weigh much higher.
Weather Sealing
LCD Screen Size and Features
Olympus TG-870 and Pentax K-7's LCD screens have the same diagonal size of 3.00 inches.
On the other hand, Olympus TG-870 features a
Tilting screen where you can change the angle of the screen to make it easier to shoot from waist or over-the-head levels whereas the Pentax K-7 has a fixed type screen which provides less flexibility in shooting positions compared to TG-870.