Dubbed "the most powerful AF in Nikon's history," the Multi-CAM 37K autofocus system uses an intelligent array of 105 all cross-type points to quickly and accurately achieve focus across the frame and in a variety of lighting conditions. This high-density system allows photographers to set focus almost anywhere within the frame in order to avoid recomposing. This unique design reduces the area of non-AF-sensitive areas in order to make the effective coverage 1.6x greater than in previous models, which allows for more accurate and faster focusing across the frame, with both still and moving subjects. When working with moving subjects, 17 custom Group Area AF settings can be used to set and maintain focus on subjects featuring busy backgrounds or fast subject movement. Benefitting the use of super telephoto lenses and teleconverters, 15 of the points are compatible with an effective aperture of f/8 and all 1053 points support working with effective apertures of f/5.6 or brighter.
Complementing the abundance of focusing points is a dedicated AF engine, which offers quick response times to benefit tracking fast and randomly moving subjects, even at the top 14 fps shooting rate. The AF engine also contributes to enhanced focusing sensitivity, with the ability to focus at -4.5 EV for working in very dark, low-contrast situations.
Furthering the versatility of the focusing system, seven different AF-area modes can be selected to support varying types of subject matter:
- Single-Point AF: The camera uses a single point to find focus.
- Dynamic-Area AF: Available with 9, 25, 49, or 105-point selections, this mode uses a primary single focus point to lock onto focus, and then makes use of the surrounding points for maintaining focus while tracking erratically-moving subjects.
- Group-Area AF: This mode treats smaller groups of AF points as a single point for a wider field of recognition and is well-suited to tracking faces or other detailed subjects.
- 3D-Tracking: Using a subject's color information, this mode utilizes all 105 points to maintain focus on a moving subject while half-pressing the shutter button.
- Auto-Area AF: This mode makes use of all 105 points to quickly identify the main subject, and then prioritizes recognized faces as portrait subjects in any AF servo mode.
In addition to the range of AF-area modes, an AF lock-on function can also be used to improve subject tracking performance and can be adjusted by two parameter—quick or delayed blocked shot AF response and erratic or steady subject movement. By configuring these settings, the AF performance can be optimized to handle a wide variety of subject movement types.
Lastly, a unique auto AF fine-tune function can be employed to ensure the best possible focus for each mounted lens. Rather than relying on photographing distance charts, this function lets you achieve precise focus manually in live view, and then have the AF system calibrate itself to the fine-tuned focus position in order to alleviate front- and back-focusing issues.