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 RS1500 and Olympus E-PL1 side-by-side from the front, back and top in their relative dimensions. Pentax RS1500 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). Olympus E-PL1 has external dimensions of 115 x 72 x 42 mm (4.53 x 2.83 x 1.65″) and weighs 334 g (0.74 lb / 11.78 oz) (including batteries).
Below you can see the front-view size comparison of the Pentax RS1500 and the Olympus E-PL1. Pentax RS1500 is clearly the smaller of the two cameras. Its body is 1mm narrower, 14mm shorter and 14mm thinner than Olympus E-PL1. As you can tell, actually this is not a fair size comparison since Pentax RS1500 has a built-in lens but Olympus E-PL1 doesn't. Once you put a lens on E-PL1, its thickness will increase significantly.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Pentax RS1500 is significantly lighter (177g ) than the Olympus E-PL1 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 E-PL1, the total kit will weigh much higher.
Weather Sealing
With its weather-sealed body, we believe that the RS1500 has a big advantage over the E-PL1 which doesn't provide any kind of environmental sealing.
LCD Screen Size and Features
Pentax RS1500 and Olympus E-PL1'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.