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 Panasonic ZS1 and Sony T900 side-by-side from the front, back and top in their relative dimensions. Panasonic ZS1 has external dimensions of 103 x 60 x 33 mm (4.06 x 2.36 x 1.3″) and weighs 229 g (0.50 lb / 8.08 oz) (including batteries). Sony T900 has external dimensions of 98 x 58 x 16 mm (3.86 x 2.28 x 0.63″) and weighs 143 g (0.32 lb / 5.04 oz) (including batteries).
Below you can see the front view size comparison of Panasonic ZS1 and Sony T900. Sony T900 is clearly the smaller of the two cameras. Its body is 5mm narrower, 2mm shorter and 17mm thinner than Panasonic ZS1.
Here is the back view size comparison of Panasonic ZS1 and Sony T900.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Sony T900 is significantly lighter (86g ) than the Panasonic ZS1 which may become a big advantage especially on long walking trips.
Unfortunately neither Panasonic Lumix DMC-ZS1 (Lumix DMC-TZ6) nor Sony Cyber-shot DSC-T900 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 Compact Cameras with Weather Sealing
LCD Screen Size and Features
Sony T900's 3.5" LCD screen is slightly larger than Panasonic ZS1's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.