Nikon D3X Live View
Nikon D3X Live View
The Nikon D3X features Live View, or the ability to see a live image from the camera's sensor on the LCD. The D3X offers two options for autofocus operation during Live View. The first Live View (Handheld mode) is the most common type. Because the traditional AF sensors are blocked when you flip up the mirror for Live View mode, you have to drop the mirror to focus, then flip it back for Live View. There's added delay in this mode versus using the optical viewfinder, to be sure, and a blackout for as long as it takes for the D3X to focus. On the other hand, this mode provides much faster autofocus performance than Tripod mode, which uses contrast-detect autofocus.
The Nikon D3X's second mode is called "Live View (Tripod mode)," this mode uses contrast detect autofocus, driven from the imaging sensor. Instead of flipping mechanical switches, the Nikon D3X simply reads data off the CMOS image sensor and evaluates how abruptly light to dark (or dark to light) transitions happen on the image plane. Contrast-detect AF isn't nearly as fast as phase-detect (which is why the shutter response of most digicams is so much slower than most digital SLRs), but at least it can focus without interrupting the Live View display.
As an added benefit, because it's working with data coming from the main image sensor, Tripod mode lets you move the AF point anywhere you want within the frame area, right out to the extreme edges. AF operation in this mode is unfortunately quite slow, so they really mean it when they call it Tripod mode. You can use it handheld, but you won't get the best results, and either camera or subject movement during the AF cycle may prevent the camera from focusing altogether.
The Nikon D3X also provides up to a 13x zoom in Live View mode: Combined with the superb LCD screen, this provides excellent focus discrimination when focusing manually. This is pretty important, as less than about 10x magnification really doesn't do the trick for getting the focus set right, but at 13x we felt we could pretty well nail the focus every time. (Still not good enough for us in our lens testing over on SLRgear, but we felt it was more than adequate for normal photographic use.)
Both the new Nikon and Canon SLRs include the ability to control the camera from a computer remotely, and that includes receiving a Live View image from the camera. You can focus, adjust settings, and fire, all from a computer. What's more, you can do it via cable or WiFi connection, with the optional WiFi adapters.
The new Nikons require optional Camera Control Pro software to enable this feature. Software for this feature is bundled with Canon DSLRs.