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What Are Camera Sensors?
In a digital camera, the image sensor is the device that collects incoming light when the shutter opens and converts that light into an electrical signal. The camera then analyzes that signal and translates the data into colors, that match the real-life image in the camera's viewfinder. The camera's image sensor is responsible for determining the overall image quality of your photos, affecting elements like depth of field, dynamic range, resolution, and low-light performance.
2 Types of Camera Sensors
There are two main types of camera sensors: CCD (charge-coupled device) sensors and CMOS (complementary metal-oxide semiconductor) sensors.
- CCD sensor: CCD sensors produce high image quality with low noise and good dynamic range. CCD sensors are common for medium-format cameras. They consume far more power than CMOS sensors.
- CMOS sensor: CMOS sensors are considerably more common than CCD sensors, and they consume less power and excel in high-speed burst shooting mode. Though they have a lower sensitivity to light and more grain, they have a quicker data rate and are cheaper to produce.
6 Ways Sensor Size Impacts Your Photos
The size of the sensor on your camera has an enormous effect on your photography, impacting the following elements:
- Image resolution: Resolution is dependent on how many megapixels your camera sensor holds—but what's a megapixel? Camera sensors contain millions of “photosites” that capture light that is translated into pixels. A million of these pixels equals one megapixel. The larger your camera's sensor, the larger the photosites, the more resultant megapixels, which allow for a better image and a higher resolution. High resolution is important to ensure that your images are high quality even when you blow up a photo to a larger size.
- Depth of field: Depth of field is the distance in an image where objects appear “acceptably in focus” or have a level of “acceptable sharpness.” If other factors are the same—aperture, focal length, camera-subject distance—a larger sensor will have a shallower depth of field (since, in order to fill the frame, larger sensors require you to either be closer to your subject or to use a longer focal length). Correspondingly, cameras with smaller sensors have larger depths of field. A full-frame camera sensor will provide you with the most flexibility when it comes to depth of field.
- Low-light performance: A large sensor contains larger photosites, which enhance the camera's ability to capture low-light photos in comparison to a small sensor.
- Crop factor: Crop factor is the ratio of the sensor size to a full-frame image sensor. Smaller sensors have a lower angle of view (how much of the frame is visible when taking a photo), which means less of your frame is captured compared to a full-frame sensor.
- Dynamic range and image noise: Larger sensors contain larger photosites, which increase the camera's dynamic range and decrease image noise. Dynamic range is the maximum difference between a photo's lightest and darkest tones, so a greater range is a positive attribute. Image noise is random specks of brightness or color, so less image noise is also a positive characteristic.
- Camera size and weight: While larger sensors have many benefits to your finished photos, don't forget to take into account that a larger sensor requires a larger lens and a potentially larger camera housing. The extra size and weight can be a nuisance for certain types of photography—like travel and wildlife photography—that require carrying your gear for long periods of time.
5 Standard Image Sensor Sizes
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- 35mm full-frame (36 x 24mm): Full-frame is the largest sensor size available and comes in both DSLR cameras and mirrorless cameras. There's no crop factor with a full-frame sensor, meaning everything visible in the viewfinder appears in your photo. The large sensor typically means the camera and lens will be bigger and heavier, so keep that in mind if your photography requires long periods of shooting. Combining a wide aperture lens with a full-frame sensor gives you an exceptionally shallow depth of field.
- APS-H (28.1 x 18.7mm): Short for "active pixel sensor," the APS-H is a large sensor available in both fixed and interchangeable lens cameras. It has a 1.3x crop factor and has a high ISO capability, resulting in less noise.
- APS-C (size varies): APS-C cameras are an especially popular mid-range camera choice for amateur photographers who wish to have some perks of a professional-level camera without overspending. Note that APS-C sensors come in different sizes depending on the brand—Canon APS-C sensors measure 22.2 x 14.8mm and Nikon, Sony, Fujifilm, and Pentax sensors are around 23.5 x 15.6mm.
- Four Thirds and Micro Four Thirds (17.3 x 13mm): The original Four Thirds System sensor is for DSLR cameras, while the Micro Four Thirds System is for mirrorless cameras. The Micro Four Thirds system has a 2x crop factor and is a good choice for still photography and high-level video recording.
- One inch (9 x 12mm): A high-end compact camera with a 2.7x crop factor, its sensor is large for a compact camera, producing photos with better image quality than comparable cameras. In addition to taking excellent still photos, this sensor is capable of producing crisp 4K video.
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