When Nikon teased the development of its new flagship professional DSLR in January, it was somewhat coy about divulging any exact specifications. But now that the Nikon D4S has been officially revealed, we know it boasts a newly developed 16.2-megapixel sensor, Nikon's new Expeed 4 image-processing engine, and the ability to shoot at almost ridiculously high ISOs.

There's no disputing the Nikon D4S is aimed squarely at professional photographers, and its US$6,500 price tag should keep it out of the hands of all but the most wealthy enthusiasts. Its size and weight also mean you'll only want to carry one around all day if you need its speed and sturdiness … and even then you'll probably want to be getting paid to do so. But for those who do need or want a professional DSLR, the D4S looks like it could be a corker.

While the Nikon D4S still has a 16.2-megapixel full frame FX-format CMOS sensor (36 x 23.9 mm), it's a newly developed one which is paired with Nikon's new Expeed 4 image-processing engine. This has enabled Nikon to improve on the already impressive low light performance and dynamic range of the two-year-old D4, and with a native ISO range of 100 to 25,600 (and a Hi-4 setting giving an ISO equivalent of 409,600), the D4S is shaping up to be an absolute low-light monster.

As with the D4, continuous shooting is possible at 11 frames per second – still a touch behind the Canon EOS 1D X – but this is now possible with auto-focus tracking and auto exposure. The buffer is also now rated as being good for 200 shots at full JPEG resolution. In positive news for sports snappers, the 51-point autofocus has gained a fifth mode, Group AF, which uses five AF points (the four surrounding one selected by the user) to provide increased stability while tracking moving subjects.

It's no surprise that the D4S is able to shoot JPEG and RAW to its combo of CompactFlash and XQD card slots, but it is interesting that Nikon has finally joined the likes of Canon in offering smaller RAW files for easier management and speeding up work flow. In this case the RAW Size-S files are 12-bit uncompressed and approximately half the size of standard uncompressed RAW files. Recognizing that many press photographers rely on out-of-camera JPEGs for speed, Nikon has worked to improve their sharpness, depth, and natural skin tones.

Movie recording has been given a boost and, following the surprising lead of the entry-level D3300, the D4S is capable of Full HD 1080p 60/50 fps. It also allows uncompressed full resolution movie output for external recording via HDMI, and supports simultaneous recording to either the CF or XQD card. Videographers will additionally benefit from improved sound recording with the range of audio frequency now selectable, with options such as Wide Range and Voice Range

Other improvements worth noting include smoother exposure transition during time-lapse and interval-time shooting, a new battery which should give between 3,000 and 6,000 shots, and the ability to transmit files faster using Gigabit Ethernet when connected via LAN. Possibly as a response to the green tint issues some D4 and D800 users reported, the color of the rear 3.2-inch and 921k dot LCD can now be customized to match studio monitors or personal preference.

While most changes have been made under-the-hood, there are a number of subtle exterior design alterations which will probably only be noticed by photographers who spend several hours per day with a D4. These include a slightly modified button layout and control buttons which have been re-shaped to improve operation in damp conditions. Thumb and middle finger rests have also been re-contoured with a smoother grip.

As befitting its professional status, and explaining its 1,350 g (2 lb 15.6 oz) weight, the 160 x 156.5 x 90.5 mm (6.3 x 6.2 x 3.6 in) camera has a chassis constructed of magnesium alloy and is sealed and gasketed from moisture, dust and electromagnetic interference. Its Kevlar/carbon fiber–composite shutter unit has been tested to 400,000 cycles.

Though we're not sure whether the Nikon D4S is a worthwhile upgrade for photographers who already have a D4 in their kit bag (mid-model refreshes rarely are) it looks like an obvious choice for professionals with a penchant for Nikon, a need for speed and some spare cash lying around.

The Nikon D4S will sell for $6,500 and is expected to start shipping in March.

Product page: Nikon D4S

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