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 Canon D30 and Nikon D40 side-by-side from the front, back and top in their relative dimensions. Canon D30 has external dimensions of 150 x 107 x 75 mm (5.91 x 4.21 x 2.95″) and weighs 855 g (1.88 lb / 30.16 oz) (including batteries). Nikon D40 has external dimensions of 124 x 94 x 64 mm (4.88 x 3.7 x 2.52″) and weighs 522 g (1.15 lb / 18.41 oz) (including batteries).
Below you can see the front-view size comparison of the Canon D30 and the Nikon D40. Nikon D40 is clearly the smaller of the two cameras. Its body is 26mm narrower, 13mm shorter and 11mm thinner than Canon D30.
Here is the back view size comparison of the Canon D30 and Nikon D40.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Nikon D40 is significantly lighter (333g ) than the Canon D30 which may become a big advantage especially on long walking trips.
Also keep in mind that body weight is not the only deciding factor when comparing two interchangeable camera bodies, you also have to take into account the lenses that you will be using with these bodies. Since both Canon D30 and Nikon D40 have the same APS-C sized sensor, their lenses for a similar focal length and aperture will be similar in size and weight.
Weather Sealing
Unfortunately neither the Canon EOS D30 nor Nikon D40 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 DSLR Cameras with Weather Sealing
LCD Screen Size and Features
Nikon D40's 2.50" LCD screen is slightly larger than Canon D30's 1.8" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.