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 Nikon D80 and Pentax RS1500 side-by-side from the front, back and top in their relative dimensions. Nikon D80 has external dimensions of 132 x 103 x 77 mm (5.2 x 4.06 x 3.03″) and weighs 668 g (1.47 lb / 23.56 oz) (including batteries). 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).
Below you can see the front view size comparison of Nikon D80 and Pentax RS1500. Pentax RS1500 is clearly the smaller of the two cameras. Its body is 18mm narrower, 45mm shorter and 49mm thinner than Nikon D80. As you can tell, actually this is not a fair size comparison since Pentax RS1500 has a built-in lens but Nikon D80 doesn't. Once you put a lens on D80, its thickness will increase significantly.
Comparison image of Nikon D80 and Pentax RS1500 Size, Weight and External Dimensions - Front View
Now lets look at the top view comparison of Nikon D80 and Pentax RS1500.
Top View Comparison image of Nikon D80 and Pentax RS1500 Size
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 (511g ) than the Nikon D80 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 D80, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather sealed body of RS1500, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to D80.
LCD Screen Size and Features
Pentax RS1500's 2.7" LCD screen is slightly larger than Nikon D80's 2.5" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.