Aside from some fairly minor styling changes the EX-Z850 is externally almost identical to the EX-Z750 before it, and continues the simple, stylish design that has served Casio well over since the EX-Z3 shuffled in the era of ultra-slim Exilim zoom cameras back at the start of 2003. The sliding lens (originally developed by Pentax and used in many of its Optio models) - along with the specially designed EXILIM Engine (a very small LSI processor) - allows a very slim body indeed (at around around 24mm a fraction deeper than the Z750), and the use of an all-metal construction keeps the size to a minimum.

Obviously being such a small camera with such a large screen and feature set means a lot of the Z850's more advanced controls are only accessible via the extensive menu system, but that doesn't mean there are no external controls; in fact the camera is littered with them. Macro, flash and drive modes get their own dedicated buttons, with file size, white balance, ISO and AF area accessible via a mini menu activated by the EX button. The left and right keys on the four-way controller can be customized to control AE-compensation, white balance, ISO, metering or self-timer. All in all for such a compact camera the EX-Z850 does a remarkably good job of putting a huge amount of control at your fingertips. And like its predecessor, it looks and feels pretty good too.

In your hand

There is no real 'grip' on the Z850 - front or rear, meaning single-handed operation is difficult (though possible if you don't mind putting your thumb on the screen). The location of the four-way controller also means that if you attempt to grip it too firmly with your right hand you risk changing the AE-compensation or flash mode. Held in two hands, however, the camera actually handles very well, feeling well-balanced and stable.

Body elements

The hefty Lithium Ion battery pack and SD card sit under a pretty sturdy spring-hinged door on the base of the camera (the battery is held in place with a small retaining latch). You can only charge the battery using the supplied dock (which is a pain when traveling), but a single charge will give you a very impressive 440 shots (CIPA testing standard) - a big improvement on the EX-Z750. Note there is an optional battery charger available.
The Z850 has around 8MB of internal memory - enough for a single best quality 8MP JPEG or a whole 16 seconds of HQ movies. If you're going to supply a camera with internal memory in the place of a memory card surely it makes sense to be a little less miserly? (Casio's answer to this point is that the internal memory is for emergencies, and that retailers can supply cards cheaper than they can, so you save money by not getting a card...).
The tiny flash sits above and to the left of the lens. It's a lot more powerful than the EX-Z750's flash, reaching up to 4.3 m (around 14 feet) at the long end of the zoom (auto ISO). You can switch to High Power flash mode (or turn on the Flash Assist option) to allow the Z850 to use higher ISO values (over ISO 200) if you need to extend the flash range. A new 'Soft Flash' option reduces output for more flattering portraits, and there is a 5 step flash output control.
As with all previous zoom Exilims, the Z850's lens retracts fully into the slim body when not in use, thanks to some very nifty engineering. I'd rather the zoom range (38-114mm equiv.) started a little wider, but that's fairly normal for this class of camera. The lens has a maximum aperture of F2.8 at the wide end dropping to a slightly disappointing F5.1 at the long end of the zoom.
In this section of the review we would normally be discussing the various connectors dotted around the camera. However the Z850 has no standard type connectors on the camera itself, all are provided by the cradle. The only connector on the camera itself is the cradle terminal, beside the tripod mount on the base of the camera.
The supplied cradle performs four functions. Firstly it acts as a charging station for the battery, drop the camera into the dock and the battery begins charging. Secondly it can be used to turn the camera into a 'Photo Stand' which runs a slide show of images on the LCD monitor. Thirdly it provides USB connectivity to a computer or direct-printer. Finally it adds audio/video output (for viewing images/movies on a television).
The huge 2.5-inch screen is a lot brighter than the one used on the Z750, and if you turn it up to +2 (the highest setting) it's one of the brightest we've ever seen, making it remarkably useable in even direct sunlight. There is a little video lag, but as is now common the refresh rate increases after you've half-pressed the shutter. The resolution is a little on the low side (115,000 pixels), but to be honest it doesn't look at all 'grainy' and is much better than most competitors.
...the viewfinder is fairly bright and clear, but is very small indeed. It also has a very conservative field of view, showing only around 75% of the scene being photographed. Two LEDs to the right of the viewfinder indicate focus and flash status.
The top of the Z850 is home to the main power (on/off) button and shutter release, which sits in the center of the zoom lever.
At the top of the rear of the camera are the play and record mode buttons. By default these buttons will also turn the camera on in their respective modes, though you can disable this function via the setup menu (if, as I did, you find they cause accidental power-ups in a case and actually break the lens... oops!). The main mode dial in the top right corner of the camera back has eight positions, with less emphasis on video than the EX-Z750, and new 'S' and 'A' positions.
The ubiquitous four way controller is used to navigate menus; the up and down keys also give direct access to macro and flash modes. In the middle sits a 'set' button, for choosing and confirming options. The left and right keys can be customized to control various shooting options, including AE compensation or ISO.
To the left of the LCD screen, on the side of the camera, is the 'EX' shortcut button. Like a cut-down version of Canon's FUNC feature, the EX button gives fast access to a mini menu covering file size, white balance, ISO and AF area. Above the EX button is the Drive button, used to access the various burst/continuous shooting modes. Our only complaint about the EX button is that its position makes it impossible to use quickly when holding the camera in one hand.