The adjustment dial only comes into play in manual mode, which you can select by pressing the dial inwards, or using the touch screen. This enables manual focusing, white balance, shutter, and iris, but only for the main lens. The aperture can be adjusted from F16 to F1.8, with up to 18dB of video gain on top of a fully open aperture. The shutter can be varied from 1/50th to 1/8000th, whilst white balance options include sun and cloud plus two indoor presets, as well as automatic and manual modes.
Further enhancing the HC-W850's enthusiast credentials, it has microphone and headphone minijacks available. There is no accessory shoe permanently built-in, but a bundled add-on slots into the rear of the device, providing a standard attachment for third-party peripherals. The positioning could mean some peripherals make the zoom rocker and photo button a little hard to reach, but the zoom at least has secondary controls via the LCD.
Aside from the manual functions, there is the fully automated Intelligent Auto setting, plus the slightly more configurable Intelligent Auto Plus. The latter provides a simple 11-step exposure control and colour adjustment, whilst otherwise being automatic. There are also special effects including a faux tilt-shift called Miniature, 8mm Movie, Silent Movie and Time Lapse. The 11 scene modes include the usual options, and there is also a slow motion option.
The slow motion works differently to most camcorders with the feature. The camcorder will switch over to a compatible mode, for example 28Mbits/sec in MP4 format, and a SLOW button will appear on the touch screen. The camcorder will record at regular speed until you press this button, when it will switch to a higher frame rate and then record this to memory at the regular frame rate, producing smooth slow motion. So you can have slow motion sequences in the middle of regular-speed footage, which is a nice capability, once you get the hang of it.
It's a sign of the times that the HC-W850's WiFi features are relegated to this point in the review. Wireless functionality is becoming rather ubiquitous in camcorders. However, Panasonic has a very comprehensive implementation, with the facility to connect the camcorder to your smartphone either directly or via an existing wireless network. You can then control the camcorder remotely with your smartphone, use it as a baby or home monitor, and configure it as a DLNA server so you can watch videos on your smart TV wirelessly. You can also connect to USTREAM and broadcast live directly to the Web.
Image quality is similarly relegated to late in the review, because we have come to expect the very best from Panasonic's high-end camcorders. The picture remains bright, saturated and noise free to satisfyingly low levels of illumination. If you analyse frames very closely side-by-side, there are some minor deficiencies compared to last year's flagship HC-X920, thanks to the latter's three sensors with the same specification individually as the HC-W850's one. But the HC-W850 still an excellent performer, and close to the best available in a consumer camcorder.
The Panasonic HC-W850 is certainly unique, and if you can find a use for the secondary camera, or just want to record yourself whilst you record others, there are no other competitors just yet. The secondary camera may be a gimmick, but at least it has been well executed. On the other hand, the £700 price means that you are paying £120 on top of the otherwise similarly specified Panasonic HC-V750 for the second lens. It's not a huge premium, but still an unnecessary expense if you never do want to watch yourself watching others.
The Panasonic HC-W850's secondary lens is novel and mostly well executed, and W850 is everything we've come to expect from a top-end Panasonic camcorder. That means you won't be disappointed, though it's worth considering the V750 if you don't fancy the extra camera feature.