As usual with Casio's ultra-compact cameras, the initial impression is very favourable. The EX-Z100 is a good looking camera, with a slim pocket-friendly all-metal body finished in semi-matt silver with chrome details. Although not the smallest camera in the range (that honour goes to the tiny EX-Z80) it is nonetheless very small and light, measuring 93 x 55 x 21.2mm and weighing just 111g minus battery and card, although if you include the very large 1300mAh Li-ion battery that weight goes up to 145g.
The layout of the Z100's controls is very simple, with a rotary-bezel zoom control (stepped with eight positions) and just five buttons on the back of the camera, one of which is the video recording trigger. As with the rest of Casio's cameras the main control is a permanent on-screen menu down the right of the wide-format monitor screen. Pressing the set button and then up or down on the D-pad accesses a useful variety of frequently-used options, including picture size, flash mode, drive mode, ISO setting, exposure compensation and the auto-shutter functions.
This feature, introduced on the Z80, is rather clever. There are three modes; smile detection, movement detection and auto-panning. The first of these is based on the face detection system and waits until your subject is smiling before taking a picture, but the other two modes are potentially more useful. The camera detects movement blur, and waits until everything in the frame is stationary before taking a picture. In a camera without image stabilisation this is a good way to avoid blurred photos. The sensitivity of these auto-detection functions can be adjusted via the same quick menu.
The Z100 also has a pretty good video mode, recording in 848 x 480 widescreen format at 30fps, although movie clips are limited to 10 minutes each and the optical zoom cannot be used during recording. There is also the YouTube video mode, which records at 640 x 480 resolution encoded in the H.264 video format used by the popular video sharing site.