Exposure Modes. The Nikon D3000 gives you all the exposure options you'd expect in a consumer SLR. Available exposure modes include Full Auto, Program AE, Manual, Aperture Priority, and Shutter Priority modes with shutter speeds from 1/4,000 to 30 seconds available in 1/3 EV steps, as well as a Bulb setting for longer exposures. Also provided are the six standard Scene modes found on most consumer Nikon SLRs (Portrait, Landscape, Child, Sports, Macro, and Night Portrait), and a Flash-Off Auto mode. New for the Nikon D3000 is a GUIDE mode designed to help users through complicated settings by letting them select what kind of photo they want to take and the camera makes the settings from there.A very nice touch that's common to other Nikon DSLRs is that, while in Program AE mode, you can rotate the Command dial to select different combinations of aperture and shutter speed settings than those normally chosen by the autoexposure system. (That is, if the automatic program would have chosen 1/125 second and f/5.6, you could instead direct the camera to use 1/60 at f/8 or 1/30 at f/11, to get greater depth of field.) This is a very handy option for those times when you need some measure of increased control, but still want the camera to do most of the work for you. We personally use this capability more than Aperture- or Shutter-priority metering in our own shooting.
An interesting feature when using Manual exposure mode is the electronic analog exposure display visible in the optical viewfinder data readout. This shows the amount the camera thinks an image will be over- or underexposed, based on the settings you have selected, and helps you find the best exposure for the subject.
Exposure Metering. Nikon has one of the most sophisticated and flexible metering systems on the market today. Like most SLRs, there are three main metering modes on the Nikon D3000: Matrix, Center-Weighted, and Spot metering. Where Nikon's system differs is in the capability of these modes. Nikon's matrix metering is called 3D Color Matrix II, as it takes color as well as distance into account. (Distance requires the use of CPU-equipped lenses.) It covers a wide area of the frame with a 420-pixel RGB sensor. The Nikon D3000's Center-Weighted metering mode gives a weight of 75% to an 8mm diameter circle in center of frame. Spot meters a 3.5mm diameter circle (about 2.5% of the frame) centered on the active focus area. (Most DSLRs only meter the very center of the frame in Spot metering mode.) The 420-pixel RGB sensor also serves to ascertain automatic white-balance, and provides assistance for focus tracking when the subject leaves the AF sensor area. Metering range is specified at 0 to 20 EV in Matrix or Center-Weighted, and 2 to 20 EV in Spot metering mode.
Exposure Lock. The AE-L/AF-L button locks the exposure and/or autofocus, useful for off-center subjects in tricky lighting. It can be programmed for AE lock, AF lock, AE + AF lock, or various other functions via the custom menu. You can also program the button to toggle instead of requiring the button to be held.
Exposure Compensation. Exposure compensation on the Nikon D3000 is adjustable from -5 to +5 exposure equivalents (EV) in 1/3 EV step increments, and is controllable in Program, Aperture-priority, or Shutter-priority modes. Note that in Manual exposure mode, the EV button becomes a shift button that changes the function of the Command dial from controlling the shutter speed to changing the Aperture. The Nikon D3000 does not support exposure bracketing.
ISO Sensitivity. ISO ranges from 100 to 1,600 and can be extended up to ISO 3,200 (Hi 1). ISO can only be adjusted in single EV steps (100, 200, 400, 800, etc.). Nikon's excellent Auto ISO feature is carried over as well, which allows you to set both the upper ISO limit (up to ISO 3,200) as well as the minimum shutter speed (selectable from 1s to 1/2,000s) required before ISO is increased automatically.
White Balance. The Nikon D3000 offers the usual white balance settings: Auto, six presets consisting of Incandescent, Fluorescent, Direct Sunlight, Flash, Cloudy, Shade, and a manual mode where white-balance is determined from a white or grey card. The Fluorescent preset has seven sub-settings consisting of Sodium Vapor (2,700K), Warm-white (3,000K), White (3,700K), Cool (4,200K), Day White (5,000K), and High Temperature Mercury Vapor (7,200K), and the manual setting allows one custom white-balance measurements to be stored. All the presets and manual settings are tweakable via a 2D fine-tuning grid display. 
Active D-Lighting. D-Lighting has proven a popular post-processing feature in Nikon's consumer digital SLRs, as well as some of the company's point & shoot models. It's a quick software process that attempts to overcome underexposed images, and bring detail out of shadows. Active D-Lighting on the D3000 doesn't have the many options found on higher-end models, though, just Off and On.
Picture Control. Nikon has standardized its Picture Control system so that camera settings for sharpening, contrast, brightness, saturation, and hue can be finely adjusted and ported to other Nikon digital SLRs that support the system. The D3 was the first camera compatible with the option, and all Nikon SLRs since, including the D3000 follow the standard. The Nikon D3000 has six presets called Standard, Neutral, Vivid, Monochrome, Portrait, and Landscape.Sharpness can be adjusted in ten steps, along with an Auto setting; contrast, saturation, and hue can be adjusted in seven steps, while hue is adjustable in three steps. There is also a five-step "Quick Adjust" setting which exaggerates or mutes the effect without having to adjust each slider individually. When Monochrome Picture Control is selected, Hue and Saturation are replaced by Filter Effects and Toning respectively. Filter Effects offers Off, Yellow, Orange, Red, and Green settings, while Toning offers B&W, Sepia, Cyanotype, Red, Yellow, Green, Blue Green, Blue, Purple Blue and Red Purple settings. Note that Picture Controls are only active in Program, Aperture-priority or Shutter-priority and Manual exposure modes, as the Scene modes already apply preset image adjustments. Of course, the Nikon D3000 also offers sRGB and Adobe RGB settings, in a separate Color Space menu.
Noise Reduction. The Nikon D3000 offers high ISO noise reduction, but only one level: Off and On. Noise reduction is performed at ISO 400 and higher. When set to Off, minimal noise reduction is performed at ISOs above 800.
Release Modes. The Nikon D3000's release modes are selected via the menu system. Release modes consist of Single Frame, Continuous, Self-timer, Delayed Remote (two second delay), and Quick-response Remote. The Nikon D3000's Continuous mode is rated by Nikon for up to 3 frames per second (we got 2.99 frames per second in our testing), for a total of 16 Large/Fine JPEGs before the buffer fills and the camera slows. Also, when shooting JPEGs of a very complex scene with a lot of sharp, fine detail may also compress less and result in lower buffer capacities.Self-Timer mode opens the shutter by a delay of 2 seconds) after the shutter button is pressed. The Remote release modes are for use with the optional ML-L3 wireless remote. The 2-second delay option is useful for hiding the remote when taking photos that include the operator.
Retouch Menu. The Nikon D3000 has an extensive Retouch menu, though not as extensive as the D5000's. The amount of image alteration that can be performed in-camera is starting to rival what basic image editing software packages can do on a computer, so much so that many users may not feel the need to use a computer for Nikon D3000 image editing at all. Retouch options include adjusting D-Lighting, red-eye correction, image cropping (trim), converting to monochrome, applying up to seven filter effects, adjusting color balance, resizing to small images (for TV, Web or email), image overlay for combining two RAW images into one JPEG, NEF (RAW) processing, "Quick Retouch" for fast adjustments to saturation and contrast, color outline, miniature effect, and stop-motion movies. The D5000 adds: straighten for fixing slanted horizons, distortion control for fixing lens distortion, fisheye effect, and perspective control. 
Auto: The camera sets everything. Used for snapshots or users who just don't want to be bothered with the details of how the camera will do its work. The AF-assist light will come on if needed, and the camera selects the AF point covering the closest subject.
Guide: Provides access to the camera's Record, Playback, and Setup options through one user-friendly, graphically rich menu system. The user is prompted to select the type of photo they're looking to achieve, and then the camera provides a recommended setup. These can then be further customized by the user, with the camera explaining the effect of each individual setting. Fully manual shooting isn't possible in this mode, but manual aperture or shutter adjustment can be made for certain types of photos.
Program: Puts the camera in charge of aperture and shutter speed, though all remaining camera settings are available. You can vary the combination of aperture and shutter speed the camera has selected by rotating the Command Dial. 
Shutter Priority: The user controls shutter speed, from 1/4,000 to 30 seconds, while the camera sets the aperture value.
Aperture Priority: The opposite of Shutter Priority mode, this mode lets the user control the aperture, while the camera sets the shutter speed. Available apertures depend on which lens is mounted on the camera.
Manual: Gives the user complete control over the exposure (both shutter and aperture settings), and provides access to the camera's Bulb shutter setting for exposures longer than 30 seconds.
Night Portrait: Uses slow shutter speed with flash, balancing the two so that night portraits look natural even with flash. Closest-subject AF is used. Use a tripod to avoid blurring.
Close up: Reds and greens are pumped up, camera selects center focus point, but other points can be chosen with the Multi-Selector. The built-in flash will pop up and fire if the lighting is too dim; tripod use is recommended. 
Sports: Uses higher shutter speeds, camera switches to continuous focus while the shutter button is held down halfway, tracking the subject in the center focus area. If the subject leaves the central AF area, the camera will follow it and judge focus from the other focus areas. The beginning AF area can be chosen with the Multi-selector. Both flash and AF illuminator are turned off and will not fire. 
Child: This mode boosts sharpness and saturation for clothing and background details, but renders skin tones soft and natural-looking. The built-in flash will pop up and fire if the lighting is too dim. 
Landscape: Boosts color saturation, contrast, and sharpening for city and forest landscape shots. Closest-focus AF is used, and the flash and AF-assist light are turned off in this mode. Use of a tripod is recommended in low light conditions. 
Portrait: Adjusts the lens aperture to soften background details to help the main subject stand out more clearly. Sharpness and color saturation are moderated somewhat, to give softer, more natural-looking skin tones. The built-in flash will pop up and fire if the lighting is too dim. 
Auto (Flash Off): In this mode, exposure is automatic but the flash is disabled, and the camera will vary the ISO up to a maximum of 3,200, to capture images using available light. The AF-assist light will come on if needed, and the camera selects the AF point with the closest subject. This mode is great for museums and other places where flash isn't permitted, more natural-looking indoor shots, etc. 