Panasonic follows the if-it-ain't-broke-don't-fix-it logic by keeping the body design essentially the same as that of their other FX-series cameras. The 3.6x optical, 28mm-to-100mm (equivalent), f/2.8-to-f/5.6 zoom lens extends from the front of the body when you turn the camera on and the zoom control takes the form of a ring around the shutter button with a nub on front that you can operate with your forefinger. The mode dial is built into the upper-right corner of the camera back, putting it out of the way but still convenient to use. Five small buttons, located to the right of the 2.5-inch, 207,000-pixel LCD on the camera back, double as menu controls and quick controls for functions including exposure compensation (plus or minus 2EV in one-third-stop steps), self-timer, flash, and review (in case you don't want to switch to full-on playback mode on the mode dial). Below these buttons are two small, round buttons for display controls and function/trash. The only other hard controls are the on/off slider and E.Zoom button, both on the camera top. This last one brings you to the far end of the optical zoom with the first press, adds digital zoom to bring you to a 7x zoom on the second press, and back to the widest angle on the third press. Of course, if you start at the far end of the zoom, then the first press will bring you to the 7x (with digital) zoom, and so on. Be careful though, since this button will cycle through the digital zoom even if you have it turned off in the menus.
Like a lot of compact cameras, the FX100 doesn't have manual exposure controls, though it does include 20 preset scene modes to help you deal with tough--or just plain unusual--shooting conditions. A pair of features helps you deal with blur. Panasonic's Mega OIS lens-shift stabilization helps combat hand shake, while Intelligent ISO control--a separate shooting mode available on the mode dial--analyzes motion in your subject and automatically raises the ISO to a limit you select in the menu to help prevent blur caused by a fast-moving subject. This can come in handy if you don't want to manually set ISO to boost your shutter speed; the camera will keep the ISO as low as possible if your subject is still, thereby minimizing noise in your images when the lighting is suboptimal. Like past FX models, you can also choose from 4:3, 3:2, or 16:9 aspect ratios in case you prefer to view your images on a TV or a digital photo frame instead of making prints. You can also select 4:3 or 16:9 ratios when capturing movies, though you're limited to 15 frames per second if you opt for 1,280x720-pixel video.
The DMC-FX100 showed good shutter lag times but was otherwise no more than average in our lab-based performance tests. The camera took a slightly sluggish 2.4 seconds to start up and capture its first JPG image. Subsequent JPGs took 2.3 seconds between shots with the flash turned off, slowing a bit further to 2.9 seconds with the flash on. Shutter lag measured 0.6 second in our high-contrast test and 1.1 seconds under low-contrast conditions, which mimic bright and dim shooting conditions, respectfully. At 12 megapixels, the burst mode clocked an average of 1.3 frames per second, but rose to 4.4fps when we lowered the pixel resolution to VGA.