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A dramatic landscape of the Tetons. An exciting wide-angle shot of July fourth fireworks. From spontaneous shots to planned-out portraits, digital single-lens reflex (D-SLR) cameras are perfect for any type of photography. They allow you to shoot automatically or manually, and to change lenses for complete flexibility and creativity. When shopping for a D-SLR, take note of these most important features and how they differ between models. Want more info on upgrading to a digital SLR? Watch this quick 2-minute demo.
1. Sensor Types
The sensor in a digital SLR is what processes the light of an image into the actual digital file. There are currently two types of sensors, the CCD (charged-coupled device) and the CMOS (complementary metal-oxide semiconductor) sensor. Both types of imagers convert light into electric charge and process it into electronic signals. The larger the sensor, the larger the photo site collecting the photons of light, resulting in a better image with more accurate colors, less noise and higher low-light sensitivity. CCD sensors include innovative chip architectures designed to enhance dynamic range or speed and are more power hungry, while CMOS sensors use less power and tend to be bigger than their CCD equivalents, resulting in larger cameras. Both sensor types allow for great photos.
2. Sensor Sizes
Digital SLR sensors are much larger — and more expensive — than the thumbnail-size imagers in point-and-shoot cameras. Larger sensors are the secret to why 10.0 megapixels from a digital SLR beats 10.0 megapixels from a compact camera. To spread the same number of pixels over a larger sensor area, the pixels (technically, photosites containing diodes) must be bigger. These photosites gather more light, so they produce less-noisy images, capturing greater dynamic range for better-looking photos.
Current sensor sizes:
This is the specified sensor size for the Four Thirds format, an open digital SLR standard created by Olympus and Kodak. Its dimension is 17.3mm by 13mm. Often found in Olympus and Panasonic D-SLRs.
This sensor is approximately size of the APS-C or APS-H film formats. Most digital SLRs use this size. APS-C dimensions are approximately 14mm by 21mm to 16mm by 24mm. APS-H dimensions are approximately 28.7mm x 19.1mm. Examples of cameras that use this sensor type include the Canon EOS Digital Rebel XSi, Nikon D80, Sony Alpha DSLR-A350, and the Canon EOS-1D Mark III.
Full-Frame (35mm Film Format)
A full-frame sensor is the same size as a standard 35mm film. Sensors this big are very expensive to build, but they eliminate focal-length magnification factor. Its dimensions are 24mm by 36mm. Examples of cameras that use this type of sensor are EOS-1Ds Mark III, Canon EOS 5D and the Nikon D3.
3. Megapixel Count
Megapixels are how resolution is measured in digital cameras. It refers to how many pixels are in the sensor chip. Mega means millions, so a 10.0-megapixel camera has 10 million pixels, arranged in grid about 3800 pixels wide by 2600 pixels tall. The more pixels you have, the more information the camera can capture and the higher the resolution of the camera.
Large prints and cropping are the top two reasons to get a camera with a large amount of pixels. For printing, the more megapixels the picture has, the larger it can be printed and still retain high resolution. A 5.0-megapixel camera can make a decent 8" x 10" print, but a 10.0-megapixel camera can make a great print at 16" x 20" or even larger. When you crop an image you are going to cut off some of the resolution, so the more you start with, the more you'll have left after cropping.
Pixels in DSLRs are larger than in compact digital cameras and typically create better images especially in lower light. Ten megapixels from a digital SLR beats 10.0 megapixels from typical compact digital cameras. This advantage is especially dramatic at higher light sensitivities (ISO 400 and greater).
The beauty of a DSLR is that you can change lenses. No digital SLR is limited to the lens it comes with. You can buy whatever type of lens you want and attach it for whatever type of picture you want to take. Choose from high-powered zooms to wide-angle lenses.
Read more about lenses.
5. Build Quality
One difference between the more inexpensive digital SLRs vs. more expensive digital SLRs is the quality of the build. Some models have stronger, more rugged magnesium-alloy exteriors with weather seals to keep out moisture and dust, and are shutter durability-tested.
6. Autofocus Modes and Point ArrangementsAutofocus capabilities are crucial to the clarity of your images and the speed at which you take them. The two most common autofocus modes are one-shot and continuous autofocus.
One-shot autofocus is idea for shooting non-moving, still subjects. How does it work? Just press halfway down on the shutter release button and the camera selects an autofocus point to use, and focuses on it. If you want to change where the camera is focusing, you simply release the shutter button, point the camera at something else, push halfway down on the shutter again and let the camera autofocus. Use this for landscapes, portraits, macro (like close-ups of flowers) or still-life photography.
Ideal for shooting moving subjects like toddlers or sporting events, continuous autofocus lets you focus quickly. Most cameras' continuous autofocus mode works by pressing the shutter release button halfway down and the camera chooses and sets an autofocus point. The main difference between continuous autofocus and one-shot mode is that if you continue to hold the shutter button halfway down, the camera will continue to adjust focus as your subject moves around the viewfinder. Set your camera to continuous autofocus if your subject is walking toward you. Another key difference between the two autofocus modes is that in one-shot, the camera will not take a photo until the focus is set, and in continuous mode, you can take pictures even if the subject is not in focus.
SLR Autofocus Point Arrangements
Old film SLRs had only one autofocus point, in the dead center of the viewfinder. This was great if your subject was in the dead-middle of your viewfinder, but made focusing on subjects to the sides, difficult. There are a few common arrangements on digital SLR autofocus systems. The reason for the several autofocus points is to make it easier for photographers to create off-center compositions and still attain clear focus.
There are typically four autofocus point arrangements: 3-point autofocuses are arranged with one point in the center and two off to the sides; 5-point systems are the same as 3-point, with additional points above and below the center point; 9-point systems place the autofocus points in a diamond pattern around the center point; and 11-point systems spread out the autofocus points to cover the viewfinder.
How does it work? Let's say you are taking a picture with a 5-point system and your subject is standing off to the left of the frame. If your camera is set up correctly, it will select and focus the left point on the subject, instead of the center point. Typically, the point in use will light up, a great visual cue telling you exactly where the camera is focusing.
7. More Controls/Buttons
Digital SLRs typically have a more functional "shooter's" design. They have easily accessible thumb and forefinger wheels for exposure settings, and buttons for other features like white balance and exposure control, and vertical position shutter releases that cut down the amount of menu surfing for the user.
8. Auto Sensor Cleaning Technology
Every time you change a lens, you run the risk of getting dust on the sensor, which causes bad pixels that will need retouching, not to mention messing with your camera?s interior. Many of the top-end digital SLRS now include a self-cleaning or "antidust" technology to remove dust and debris from the sensor. Most cameras include an antidust technology or auto sensing cleaner that vibrates the sensor on startup to dislodge dust particles. A low-pass filter at the front of the sensor shakes off dust automatically for better-quality SLR images.
9. Live View LCD
Live view LCD on a digital SLR camera lets you preview a photo you're about to take using the large LCD on the back of the camera. A live view LCD is great for people who don't want to be limited to viewfinder composition, and enjoy taking photos from the hip, high up, or from odd angles. The continuous image displayed on the LCD helps ensure that you're getting the composition right, even when your eye isn't pressed to the viewfinder.
10. HD Video Recording
A growing trend in digital SLRs, many models now can record in high-def video directly from the camera. High-definition movie mode lets you capture full HD video clips to watch on the camera's LCD screen or on your HDTV (via camera hook-up).
11. Optical Image Stabilization
Blurry pictures are a big disappointment. Optical image stabilization helps control and correct movement if the camera shakes or even if the subject moves while you are trying to take a picture. Optical image stabilization (on the digital lens itself) senses the movement of the camera and physically shifts the glass elements inside the lens to correct for the movement.
Go forth and shop!
Buying a digital SLR is an investment in both money and time, but the results in your photos make it worthwhile. Take your time when shopping to ensure you get the one that's right for you. Shop our selection of DSLRs.