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 FujiFilm S2800HD and Sigma DP3 Merrill side-by-side from the front, back and top in their relative dimensions. FujiFilm S2800HD has external dimensions of 110 x 74 x 82 mm (4.33 x 2.91 x 3.23″) and weighs 437 g (0.96 lb / 15.41 oz) (including batteries). Sigma DP3 Merrill has external dimensions of 122 x 67 x 59 mm (4.8 x 2.64 x 2.32″) and weighs 330 g (0.73 lb / 11.64 oz) (including batteries).
Below you can see the front view size comparison of FujiFilm S2800HD and Sigma DP3 Merrill. FujiFilm S2800HD is 12mm narrower and 2mm thinner than Sigma DP3 Merrill but it is also 7mm taller.
Here is the back view size comparison of FujiFilm S2800HD and Sigma DP3 Merrill.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Sigma DP3 Merrill is significantly lighter (107g ) than the FujiFilm S2800HD which may become a big advantage especially on long walking trips.
Unfortunately neither FujiFilm FinePix S2800HD (FinePix S2900HD) nor Sigma DP3 Merrill provides any type of weather sealing in their body, 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 Bridge Cameras with Weather Sealing Top Compact Cameras with Weather Sealing
LCD Screen Size and Features
FujiFilm S2800HD and Sigma DP3 Merrill's LCD screens has the same diagonal size of 3".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.