In order to provide a dense area of focus points that accurately capture the subject, regardless of the kind of movement, the D3 and D300 have incorporated the newly designed Multi-CAM 3500FX (D3) and Multi-CAM 3500DX (D300), both of which boast 51 focus points, the world’s largest number*, achieving an outstanding level of focus acquisition where the focus points almost never leave the subject. Ever since the early development of the F5, Nikon has constantly sought to construct the AF algorithm in such a way that the focus points would always keep the subject, and with these cameras, our work has reached its fulfillment. In particular, in order to strongly support the photographer when shooting fast-moving subjects, the cross-type sensors have been distributed in a dense layout, located in the center of the frame, that covers the optimum positions. When shooting in Dynamic-area AF mode (9-point) for example, if you select a focus point in the center, all of the eight surrounding cross-type sensors work as a backup, demonstrating an outstanding level of focus acquisition performance that has never before been available with erratically moving subjects. Moreover, Nikon felt that all 15 cross-type sensors should maintain a high standard of performance whichever NIKKOR lens was used. If all 15 cross-type sensors were able to demonstrate their full performance with any NIKKOR lens without exception, the camera would easily capture a subject, leaving the photographer to concentrate on composition and decisive moments. And, indeed, that’s what we accomplished: All 15 cross-type sensors retain the same outstanding level of performance with any NIKKOR lens as fast as f/5.6** to properly support professional photographers.
* For D-SLR cameras (as of Aug. 23, 2007, based on Nikon research)
** Except when certain lenses are used in combination with a teleconverter, constituting an effective aperture of f/5.6
All 15 cross-type sensors retain the same outstanding level of performance up to f/5.6
The D3 and D300 are equipped with versatile AF-area modes, enabling the photographer to deal accurately with a range of diverse shooting conditions. Single-servo AF (AF-S) mode is used to fix the focus on a stationary subject for landscapes, portraits, still-life shots, and such, and Continuous-servo AF (AF-C) mode is use to continuously track the movement of moving subjects.
Single-point AF mode using only a single selected AF point from among the 51 is recommended when you want to accurately focus on a particular part of your subject or when you need to choose a certain AF point for compositional reasons. Single-servo AF (AF-S) is your choice when shooting stationary subjects, and Continuous-servo AF (AF-C) is effective for shooting moving subjects such as motor sports, track and field, and so on, where you’re able to easily line up the focus point on the desired point of your subject.
Dynamic-area AF mode is used in combination with Continuous-servo AF (AF-C). Dynamic-area AF mode (using 9 points) is recommended when shooting irregularly moving subjects, such as soccer players or skiers, or when you want to reflect a particular intention on the focus point and/or composition when shooting moving subjects of low contrast. Even if the subject moves out of the initially selected focus point, the surrounding eight focus points will continue capturing the subject. This mode demonstrates its strengths when it is difficult to focus on the desired subject point with Single-point AF mode. Also, this mode requires the least amount of defocus calculation, thereby giving you the fastest focusing among the Dynamic-area AF modes.
In this mode, the selected focus point and the 20 surrounding focus points capture the subject. This mode is effective when it is difficult to capture a subject making sudden dynamic movements with Dynamic-area AF mode (using 9 points).
Effective when subject movement is unpredictable and a larger area must be used. The 50 points surrounding your selected point serve as backup.
This mode makes effective use of the Scene Recognition System, recognizing the color and brightness of your subject when the shutter release button is halfway pressed, then tracking the subject as it moves, and automatically shifting the focus point. This significantly improves the performance of subject tracking when your subject moves up, down, left or right. Because you no longer have to line up the focus point with the moving subject and continue following it, you can concentrate on composing your image. Even for snapshots or portraits, after locking the focus and shooting while changing your composition, the focus points automatically change to track the moving subject within the frame. And even when the distance to the subject changes, the autofocus continues, effectively tracking and keeping the subject in focus.
In this mode, the camera automatically detects the main subject, selects a focus point from among the 51 points and focuses on the subject. When there is a person within the frame, the Scene Recognition System’s subject identification information distinguishes the subject’s skin tone from background and foreground so that the camera automatically prioritizes focus on the person regardless of his or her position within the focus points coverage area. When there are several people, the camera focuses on those in front. If there are no people in the scene, the camera focuses on the most likely subject, judging from the available focus-points information. As the camera automatically selects the focus point, this mode is convenient when you want to concentrate on shutter release timing for shooting snapshots or portraits, assigning focus selection and operation to the camera. It’s also convenient for responding to spur-of-the-moment shooting, when you have no time to select a focus point beforehand. When shooting with Live View’s Hand-held mode, this mode proves effective as you do not have to look through the viewfinder to select a focus point. With a stationary subject, this mode is recommended in combination with Single-servo AF (AF-S). When the subject is focused, all active focus points are illuminated for about one second, allowing you to confirm focus points used.
| AF-Area Modes | Focus Modes | ||
|---|---|---|---|
| AF-S | AF-C | ||
| Single-point AF | Suitable when a photographer wants to reflect a particular intention for composition and/or focus point for shooting a stationary subject | Suitable when a photographer wants to reflect a particular intention for composition and/or focus point for shooting moving subject | |
| Dynamic-area AF | 9 points | Operates in essentially the same manner as Single-point AF mode | Suitable for shooting erratically moving subjects or subjects with low contrast |
| 21 points | Suitable for shooting moving subjects that nine points cannot cover | ||
| 51 points | Suitable for shooting moving subjects that 21 points cannot cover | ||
| 51 points (3D-Tracking) |
Suitable for shooting moving or stationary subjects, so you can put priority on composition | ||
| Auto-area AF | Suitable for shooting snapshots, leaving focus selection up to the camera, and for Live View’s Hand-held mode | Suitable for shooting moving subjects, leaving focus selection up to the camera, and for Live View’s Hand-held mode | |
The Multi-CAM 3500FX/DX autofocus sensor module focuses with high speed and precision under diverse shooting conditions. Its performance is supported by multiple systems.
A CCD sensor is employed as the autofocus sensor, covering a large area within the frame. With low noise characteristics, this sensor is able to detect even low-brightness subjects. It has a pitch minute enough to properly detect low-contrast subjects, such as a small human face and clothes with less distinctive patterns.
Of paramount importance for focusing precision is the separator lens located in front of the AF sensor to accurately transmit incoming light from the NIKKOR lens to the AF sensor. An anti-reflection coating was used for the condenser lens that serves as an entrance for light into the AF sensor, as well as for the separator lens, thereby achieving high-contrast light transmission performance. The separator lens, the size of a grain of rice, boasts a phenomenally high-precision, double-side curved surface structure, providing the autofocus sensor with accurate high-resolution images. Because the index of the curved surface varies, an extremely refined fabrication technology is required to achieve the correct formation of both sides of the plastic needed to ensure optimum images.
Nikon was able to realize this double-sided curved surface as the optimum solution for a high-accuracy separator lens thanks to our unique proprietary fabrication technology. Furthermore, the exceptionally stable cycling movement of the sub mirror for focusing significantly contributes to uniform high AF performance for both single-frame and high-speed continuous shooting.
These multiple mechanisms, working together, ensure that the camera focuses on the desired subject with proven certainty, without the occurrence of front or rear focus. The AF systems for the D3 and D300 also decisively capture subjects that have long been considered difficult, such as a bicycle passing at a close distance or a train slowly moving toward a station platform.
When shooting sports such as basketball or soccer, if the target player is momentarily blocked by a referee or obstructed by another player, the Focus Tracking with Lock-on function enables you to keep focused on your subject. With the D3 and D300, this function is even more sophisticated. The time that a targeted subject can be kept in the lock-on state when obstructed has been extended, enabling you to decisively capture the subject.
