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 E90 and Pentax S1 side-by-side from the front, back and top in their relative dimensions. Pentax E90 has external dimensions of 102 x 59 x 25 mm (4.02 x 2.32 x 0.98″) and weighs 145 g (0.32 lb / 5.11 oz) (including batteries). Pentax S1 has external dimensions of 114 x 58 x 28 mm (4.49 x 2.28 x 1.1″) and weighs 157 g (0.35 lb / 5.54 oz) (including batteries).
Below you can see the front-view size comparison of the Pentax E90 and the Pentax S1. Pentax E90 is 12mm narrower and 3mm thinner than Pentax S1 but it is also 1mm taller.
Here is the back view size comparison of the Pentax E90 and Pentax S1.
Now lets look at the top view comparison of Pentax E90 and Pentax S1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Pentax E90 is 12g lighter than the Pentax S1 but we don't think this will make a significant difference.
Weather Sealing
Unfortunately neither the Pentax Optio E90 nor Pentax Optio S1 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 Compact Cameras with Weather Sealing
LCD Screen Size and Features
Pentax E90 and Pentax S1's LCD screens have the same diagonal size of 2.70 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.