Nikon D7000 Optics
Nikon D7000 Optics
The Nikon D7000 is sold body-only, or bundled with the Nikkor AF-S DX 18-105mm f/3.5-5.6 G ED VR 5.8x zoom lens. Optical construction consists of 15 elements in 11 groups with one element using ED glass and one hybrid aspheric surface. (A hybrid aspheric lens consists of a normal spherical-section glass lens with a thin plastic layer bonded to it that provides a molded aspheric surface. They provide the benefits of aspheric surfaces (reduced distortion and aberration) at lower cost than all-glass aspherics.) Maximum aperture ranges from f/3.5-5.6 from wide angle to tele, while minimum aperture ranges from f/22-36.
The long list of alphabetic jargon in the lens's name deserves some translation for the non-Nikonians who might be reading this, so here it is:
- AF-S - "Silent Wave" (SWM) motor for fast, quiet focusing. This design also lets you adjust focus manually after the autofocus system has achieved focus, handy for manually tweaking focus to your liking in tricky situations.
- DX - designed to mate with Nikon's DSLRs, smaller and lighter because its image circle doesn't have to cover the full 35mmm film plane.
- 18-105mm - A fairly wide zoom range, 5.8x from wide to tele, equivalent to a 27-157.5mm lens on a 35mm camera.
- f/3.5-5.6 - A fairly average maximum aperture range, typical of most of Nikon's kit lenses.
- G - It has a CPU so it will work with Nikon's 3D Color Matrix Metering II system. The G also means no aperture ring, you set the aperture only through the camera's controls. Speaking of aperture, the diaphragm in this lens is a 7-blade rounded-opening design, for nice round catchlights and more appealing bokeh. (A more natural blur for out-of-focus objects.)
- ED - Uses Extraordinary Dispersion glass for better control of distortion, astigmatism, and chromatic aberration. As noted, there's also one aspheric surface, down from no fewer than 7 in the previous 18-135mm kit optic.
The lens focuses quite closely, to a maximum repro ratio of 0.2x (1:5 macro), and accepts 67mm filters. This is a slightly reduced macro capability over the previous 18-135mm, which could get to 0.24x. It's nice that the lens takes a 67mm filter, that seems to be a fairly common size on Nikon's lenses, so you'll have a better chance of using the same filters on multiple lenses. As its VR designation indicates, this lens also incorporates Nikon's excellent Vibration Reduction (Image Stabilization) technology. The overall dimensions of the lens are 76mm diameter by 89mm long, and it weighs in at 420 grams. This lens adds about $300 to the price of the body when purchased as a kit, but costs about $400 when purchased alone (though you should be able to find it on sale for less these days).
The new kit lens felt very nice in the hand. It zoomed smoothly, focused quickly, and construction was solid and tight. Optical performance was quite good, and VR is a welcome addition. Along with the test results presented below, see our full review of the Nikkor 18-105mm VR lens on our sister site, SLRgear.com.
Like other Nikon SLRs, the D7000 accommodates a wide range of Nikkor lenses, via the standard Nikon "F" lens mount. Unlike the Nikon D3100 and D5000 consumer models, however (as well as the D40, D40X, D60 and D3000 before them), the D7000's lens mount includes both a mechanical AF coupling for older "screw-drive" autofocus lenses, as well as AF electrical contacts for the latest AF-IF or AF-S Nikkor lenses with internal focus motors.
The Nikon D7000 has an APS-C sized sensor which is smaller than 35mm film, so it's designed to work with "DX" lenses as well as full-frame "FX" lenses. As mentioned previously, DX lenses tend to be smaller and lighter than full-frame models with the same focal length and maximum aperture. The sub-frame sensor on the Nikon D7000 means that it has a smaller angle of view (by a factor of 1/1.5x) than a full-frame camera with any given lens. While most properly called a "crop factor," the 1.5x ratio is most commonly referred to as the "focal length multiplier," since that's how it works in practice: Any lens used on the Nikon D7000 will have the same field of view as one with a 1.5x greater focal length will when attached to a 35mm camera. For example, a 100mm lens on the D7000 will show about the same field of view as a 150mm lens on a camera with a 35mm frame size.
The Nikon D7000's lens mount includes an AI aperture ring connector, a little metal vane located just outside the lens mount flange (at about 1 o'clock), that interfaces with old AI Nikkor manual focus lenses. This engages with the aperture ring on AI-style Nikkor lenses, and lets the D7000 support aperture-priority metering mode and provides manual-exposure metering with them. Lower models including the D90 do not have this feature, so the D7000 is compatible with a wider range of older Nikkor lenses than its lesser siblings.
With few exceptions, you can use the Nikon D7000 with any F-mount Nikkor lens made since 1977. See the table and notes below for detailed lens compatibility information extracted from the D7000 User's Manual (courtesy of Nikon USA):
Nikon D7000 Autofocus System
Phase-detect AF. Autofocus is an area that's received significant attention from the Nikon D7000's designers. The company has developed a new Multi-CAM 4800DX autofocus sensor, which includes 39 AF points, including nine cross-type sensors at the center of the image frame, operable with every autofocus Nikkor lens. That's 12 fewer AF points than the D300S, but a major improvement over the D90's 11 point system. The 39 focus points cover much of the image frame (see the Viewfinder tab for the AF array), and the Nikon D7000 includes 3D tracking capability that follows moving subjects from point to point as they traverse the frame with the help of the 2,016-pixel RGB sensor (more about that below). For manual point selection, when a 39-point system might prove overly complex, it's possible to restrict the number of manually selectable points to a subset of 11 points throughout the frame. Nikon has also improved AF control in the D7000, with a new button positioned centrally in the Focus Mode switch used to select the AF point in concert with the camera's control dials to select autofocus mode, active points, etc. Detection range for the D7000's AF system is -1 to +19 EV (ISO 100, 68°F / 20°C).
Focus modes. The Nikon D7000 lets you choose either auto or manual focus via the small Focus Mode switch on the front of the camera, next to the lens. Setting the switch to "M" puts the camera into manual focus mode, "AF" places it in autofocus mode. Single AF (AF-S), Continuous AF (AF-C), and Auto-switching AF (AF-A) options are selected by pressing the button in the center of the switch and rotating the rear command dial, to cycle through the choices. The control panel and viewfinder display the current mode as it's being adjusted. Single AF simply means that the camera sets focus only once, when the Shutter button is first pressed halfway, and is best for stationary objects. Continuous AF means that the camera continuously adjusts the focus with predictive focus tracking, as long as the Shutter button is halfway pressed, and is best for moving objects. In AF Auto mode, the camera begins focus operations in Single AF mode, but switches to Continuous AF if it detects motion within the active AF area.
Like the D300S, Release or Focus Priority can be selected for both AF-S and AF-C modes via a Custom menu a1 and a2 settings. In Focus Priority mode (the default for AF-S mode), the shutter won't release unless the lens is focused, or the lens itself is set to manual focus. However, in Release Priority mode (the default for AF-C mode), the camera will fire regardless of the state of focus. If you want to be sure that the camera is focused when you snap the picture, use Focus Priority mode. Use Release Priority for moving subjects, and/or times when the instant of shutter release is more important to you than sharp focus. A "Focus Tracking with Lock-On" option in Custom menu a3 allows you to adjust how long the camera waits before adjusting focus if the distance to subject changes abruptly, for example by something passing between the camera and the subject. Options range from 1 second (Short) to 5 seconds (Long) in 1 second steps, along with an Off option.
AF-area modes. Pressing the Focus Mode button and rotating the front dial allows you select the AF Area mode. Available options are: Single-point AF, 9-point Dynamic-area AF, 21-point Dynamic-area AF, 39-point Dynamic-area AF, 3D-tracking and Auto-area AF modes. Single Area AF simply means that the camera judges focus based on one part of the subject, and the user can manually select the AF point by pressing the arrow keys. The other modes are rather more complex, offering the ability to automatically track moving subjects, determine scene types and even recognize the location of human subjects in a scene.
Dynamic-area AF is relevant only when in Continuous-servo AF mode, with its behavior mirroring that of Single-point AF when in Single-servo mode. Dynamic-area AF employs all or a subset of the autofocus points, though you can still manually select the starting point for AF operation. When Dynamic-area focusing is enabled, the camera first focuses on the subject in the primary focus area. When the subject moves to a different AF area, the camera shifts the focus to "follow" the subject. This is great for irregularly moving subjects. (Sports and kids come to mind.) As well as allowing tracking across all 39 AF points, at the user's option the camera can limit subject tracking to only a small area of 9 or 21 points including the user-selected starting point. As noted, you can manually select different starting points, and the cluster of Dynamic-area points will follow your selection. As an aid to users transitioning from the D90's system, there's also an option that lets you choose a single active point from a selection of 11, roughly matching the AF point layout of the D90 and some older models.
The final point selection option in Dynamic-area AF is the 3D Tracking mode, which allows the camera to use the 2,016-element RGB exposure/white balance sensor to aid in subject tracking. This sensor has been enhanced over the D300S's 1,005 pixel version and is used by Nikon's excellent 3D Matrix Metering system. In matrix metering, patterns of tone and color are used as an index into a large database of "reference scenes" stored in the camera's memory. The camera doesn't directly understand it's snapping a portrait shot, but when it sees a human-shaped blob against a different color background, its scene indexing tells it that it should try to get the exposure of the blob correct, even if it means the overall scene brightness would come out low.
Starting with the D3 and the D300, the Nikon engineers have used the data from the RGB exposure sensor to help guide the camera's autofocus decisions. While the RGB sensor provides no distance information, it has much more resolution than even the large array of AF points on the Multi-CAM4800 AF sensor. The 2,016 element RGB sensor also captures both tone and color information, making it easier to discern where objects are in the field of view and how they're moving.
With this RGB-assisted AF approach, when an AF point initially acquires a lock on a particular subject, the camera immediately notes the pattern of light and color found at the corresponding point on the RGB array. Then, as the subject or camera moves, the camera can track the light/color pattern corresponding to the subject across the face of the RGB array. This provides much finer-grained position information than could ever be obtained from the sparse AF array. The RGB sensor doesn't provide any distance information, but by more precisely tracking subject information, it permits a much surer hand-off of the subject between AF points.
In Auto-area AF mode, the camera chooses which AF points to use automatically, with the selected points shown briefly in the viewfinder for reference when in Single-servo AF mode. The camera automatically determines the subject type, and bases AF point selection on its decision of the main subject in the scene. When using either G- or D-type lenses, this becomes rather more intelligent, with the camera able to use its 2,016-pixel RGB sensor to distinguish human subjects from the background. This allows the D7000 to automatically select the focus points located over your human subject(s).
Changing AF points & locking focus. In any of the AF modes, you can change the primary focus area by unlocking the focus area selector (the Four-Way Arrow pad on the back panel) and then shifting the focus area using the up, down, right, or left arrow directions on the control rocker. You can lock the focus area selection by turning the switch below the control rocker back to the lock position. By default, the Nikon D7000 does not "wrap" the focus area selector as you scroll between focus areas. Custom Setting a5 lets you opt for a "wrap" function. What this means is that if you press the right arrow key again, after the right focus area is already selected, the selection will immediately jump to the left focus area. The same thing happens when moving the focus area selection vertically as well.
There are several methods by which you can lock focus on the D7000. The first is to half-press the Shutter button to lock the focus, placing your subject in the selected focus area, halfway pressing the Shutter button, then realigning the composition and firing the shutter. Alternatively, when using Single Servo AF, you can press the AF-L/AE-L button (or through Custom Function f3, the Function button, or f4, the Preview button) to lock focus, even if the Shutter button is released. This lets you recompose the photograph without keeping your finger on the Shutter button, but on the AE-L/AF-L button instead. (Reducing the chance that you'll accidentally trip the shutter when you don't intend to.) The D7000 has no dedicated AF-ON button like the D300S, but the AE-L/AF-L can be programmed to act as one. In this case, the shutter button will not perform autofocus.
Nikon D7000 AF "Fine Tuning"
The Nikon D7000 also supports AF fine-tuning to address back- or front-focusing lens issues, a feature previously only found on higher-end models such as the D300 and up. You can register up to 12 different lens "types" with the camera (more on "types" in a moment), and make micro-adjustments to the AF system for each, across a range of +/-20 (arbitrary) increments.
What does lens "type" mean here? Basically, a lens "type" is a lens model. For instance, if you have a 70-200mm f/2.8 and a 100mm f/2.8 Micro, the camera would recognize each lens when it was attached to the camera, and automatically load the appropriate fine-tuning setting. If you had two 70-200mm f/2.8s, though, the camera would have no way to distinguish between them, and would load the same fine-tuning settings for either one.
While there may be some photographers (particularly pros) who have more than 12 lenses in their kits, the 12-lens "fine-tuning library" will cover the needs of the vast majority of D7000 users. We've found that this system also recognizes lens types for third-party lenses as well, so its utility extends to essentially any CPU-containing AF lens the Nikon D7000 can work with.
The lens-based AF tuning function can also be disabled altogether, if you want to revert to the standard focus tuning for all lenses. It should be noted that AF fine tuning only affects phase detection autofocusing, having no effect over contrast detection AF in Live View mode. (It's also an option best left disabled unless you know you have a front- or back-focusing issue with one or more of your lenses, because the system can also be used to manually introduce a focusing error, perhaps making it impossible to focus to infinity, or the ordinary macro focusing distance of a lens.)
AF fine-tuning has by now become a fairly standard feature on higher-end SLRs. That doesn't diminish the fact that it's a huge step forward in focus accuracy, though, giving photographers the tools they need to maintain and calibrate their own equipment.
Nikon D7000 AF Assist
The Nikon D7000 has a bright, dedicated autofocus-assist lamp, which also doubles as a self-timer lamp. We prefer this setup over using the flash strobe for AF assist, as this totally decouples autofocusing from flash operation. (The flash does not need to be raised or active.) The AF assist lamp illuminates automatically in poor lighting conditions, and can be disabled via a Custom menu setting a7. The effective range is specified by Nikon as 0.5-3m or 1.7 -9.9 ft.
Nikon D7000 Live View Focusing Options
In Live View mode, the Nikon D7000 offers only contrast-detection autofocus (The D300/D300S gives you a choice between phase-detection and contrast-detection in Live View, but doesn't offer the more advanced contrast-detection modes or Full-time servo mode mentioned below.) There are three focus modes in Live View: Single-servo AF (AF-S), Full-time servo AF (AF-F) and manual focus (MF). Of note is AF-F mode which is similar to AF-C mode when using the optical viewfinder (though you don't have to half-press the shutter button), as the D7000 is only the second time a Nikon SLR offers continuous full-time autofocus in Live View and Movie modes. (The D3100 was the first.) There are four AF-area modes in Live View mode: Face-priority AF, Wide-area AF, Normal-area AF and Subject-tracking AF. Face-priority is useful for portraits. Up to 35 faces can be detected and when more than one face is present, the D7000 will select the closest one. You can also manually select which face to focus on using the multi-selector. Wide-area is recommended for landscapes and other non-portrait shots. Normal-area offers a smaller focusing area, and is useful for focusing on a small area of the frame. With either Wide- or Normal-area, you can move the active focus area with the multi-selector. Using a tripod is recommended. Subject-tracking attempts to track a selected subject as it moves through the frame. You position the focus point over your intended subject and press the OK button to begin tracking. To end tracking, press the OK button again. Note that Subject-tracking AF may be unable to track a subject if it's too small, moves too quickly, is similar in color to the background, changes sizes, or if the subject and background are very bright or dark, etc.
Nikon D7000 Anti-Dust Technology
To help combat dust particles that can enter the camera when changing lenses, the Nikon D7000 includes an ultrasonic dust cleaning system to automatically vibrate the low-pass filter over the sensor each time the camera is turned on or off (programmable). There is also an immediate mode where cleaning takes place on demand, and of course, there's a manual cleaning mode, where the camera lifts the mirror and opens the shutter, allowing access to the low pass filter with a blower or other cleaning device. You can also capture an "Image Dust Off Reference Photo," and use the optional Capture NX2 software to remove dust shadows from your images via post-processing.
While ultrasonic dust removal systems can increase the interval between manual cleanings, it bears noting that no such system can completely eliminate the need to occasionally clean the sensor manually. Copper Hill Images is an advertiser of ours, but we'd recommend their wet/dry cleaning system even if they weren't (it's what we use in our own lab): See the Copper Hill website for details.
Kit Lens Test Results
Very good performance with the 18-105mm VR kit lens.
|18mm, f/8||105mm, f/8|
The Nikon D7000 is available with a Nikkor AF-S DX 18-105mm f/3.5-5.6G ED VR (Vibration Reduction) lens, which has a better-than-average zoom ratio of about 5.8x for a kit lens. Details are pretty good across the frame at full wide-angle, with minimal corner blurring. There are low levels of coma distortion in the leaves at the corners, and chromatic aberration isn't an issue because most of it is removed by the D7000's image processor (see below). Results at full telephoto are also quite good, showing strong detail across most of the frame with some minor softness in extreme corners. (These shots were both taken at f/8. See below for how the lens performs at maximum aperture.) Overall, a very good performance for a kit lens, and the built-in Vibration Reduction (Nikon's term for optical image stabilization) will come in handy for hand-held shots in low light.
A larger-than-average macro area with the kit lens, with soft detail overall. Flash throttles down pretty well.
|Macro with 18-105mm Kit Lens
|Macro with Flash
The Nikon D7000 captured a larger-than-average macro area with the standard 18-105mm kit lens, measuring 4.18 x 2.77 inches (106 x 70 millimeters). Detail was somewhat soft, and there was some additional softening in the corners. (Most lenses have some softening in the corners at macro distances.) Some vignetting is also noticeable in the extreme corners. The Nikon D7000's flash throttled down for the macro area pretty well, though.
High levels of geometric distortion at wide-angle and telephoto ends with the 18-105mm kit lens.
|Barrel distortion is 1.1 percent at 18mm|
|Pincushion distortion is 0.6% at 105mm|
The Nikon D7000's 18-105mm kit lens produced about 1.1 percent barrel distortion at wide-angle, which is higher than average and noticeable in its images. At the telephoto end, there was about 0.6% of pincushion distortion which is also higher than average and noticeable. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide-angle) or inward (like a pincushion -- usually at telephoto).
Auto Distortion Control
Low geometric distortion when Auto Distortion Control is enabled.
|Barrel distortion at 18mm is 0.5 percent|
|Pincushion distortion at 105mm is 0.1 percent|
The Nikon D7000 offers an Auto Distortion Control feature to reduce geometric distortion automatically. As you can see it worked quite well with the 18-105mm lens, reducing barrel distortion at wide-angle to 0.5%, and pincushion at telephoto to 0.1 percent. Since this option is database driven, it's only available for Nikkor D and G-type lenses with certain optics such as Fisheye and Perspective Control lenses excepted. Auto Distortion Control is Off by default. You can also apply Auto or Manual Distortion Control to JPEGs after the fact, in the Retouch menu. Manual mode works with images from any lens.
Chromatic Aberration and Corner Sharpness
Very low C.A. in JPEGs, higher in uncorrected RAW files. Some blurring in the corners of the frame at wide-angle and telephoto with the kit lens wide-open.
|Wide, f/3.5: Lower right
C.A.: Very low
Softness: Slightly soft
|Wide, f/3.5: Center
C.A.: Very low
|Tele, f/5.6: Lower left
C.A.: Very low
Softness: Moderate blurring
|Tele, f/5.6: Center
C.A.: Very low
Softness: Slightly soft
Chromatic Aberration. Chromatic aberration is quite low at the full wide-angle setting of the Nikon D7000's 18-105mm VR kit lens. At telephoto, chromatic aberration is even lower and hardly detectable. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.) The Nikon D7000's image processor does a good job at automatically removing most C.A. from JPEGs, and it works with any lens. (See below for crops from uncorrected RAW files.)
Corner Sharpness. The Nikon D7000's 18-105mm VR kit lens produced slightly soft corners of the frame at full wide-angle. The lower right corner was a touch softer than the other corners, and the softness didn't extend very far into the frame. The center was reasonably sharp. At full telephoto, the left hand side corners were softer than the right. The lower left corner was the softest, with some softness extending fairly far into the frame, but the lens was softer overall at telephoto than at wide-angle. There's also a little bit of vignetting (corner shading) at both ends of the zoom, as indicated by the darker corner crops. Still, these are better-than-average results for a kit lens, considering the zoom ratio and that the aperture was wide-open for these shots. (Corner sharpness and vignetting typically improve as the lens is stopped-down from maximum aperture.)
Much higher levels of C.A. at wide-angle and telephoto in RAW files.
|Wide: Lower right
C.A.: Moderately high
Softness: Moderate blurring
C.A.: Very low
|Tele: Lower left
C.A.: Moderately high
Softness: Moderate blurring
C.A.: Very low
Softness: Slightly soft
As you can see from the crops above, levels of chromatic aberration in the corners are much higher in uncorrected RAW files, though still reasonable. Nikon has been automatically reducing C.A. in its JPEGs for a while now in their DSLRs, so this is no surprise. (Note that these crops are unsharpened, so they appear softer than the camera JPEGs.)
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Nikon D7000 Photo Gallery .