Take control of the autofocus points
While the focus mode determines how the camera focuses, the AF-area mode determines where it focuses. As with autofocus modes, there’s a trio of core AF-area modes common to the Nikon range. Single-point AF enables you choose any of the available AF points in the viewfinder – perfect when you want precise control over where the camera is focusing. Dynamic-area AF lets you choose from a set number of active AF points – typically 9, 21 and 39/51, depending on the camera – while Auto-area AF uses colour and face recognition to automatically follow a subject across the array of AF sensors. The more of these there are, the more likely the camera will be able to smoothly keep track.
It’s not just the overall number of focus points that make a difference, but the type of focus points too. Cross-type focus sensors are steadily becoming the standard Once confined to the single centre focus point only, the more precise cross-type focus sensors are now typically dotted throughout the AF sensor array. Some sensors only offer cross-type performance at certain apertures, and you may need a fast lens – one with a large maximum aperture such as f/2.8 – in order to trigger the full complement. Some cameras also boast ‘f/8’ autofocus performance, which is useful when attaching a teleconverter to a telephoto lens. A teleconverter reduces the effective maximum aperture of the lens, but with f/8 autofocus you can use a 2x teleconverter on an f/4 lens and still retain the benefits of autofocus.