What Is Sensor Size?

What Is Sensor Size?

The sensor is the part of the camera that captures light, and its physical size has a huge impact on your images. Sensor size is measured in millimeters, and it determines how much light the camera can gather in a single exposure. A larger sensor has more surface area, which means more photosites, bigger photosites, or both. Bigger photosites capture more light and produce cleaner images with less noise.

The most common sensor sizes are full frame, APS-C, and Micro Four Thirds. Full frame measures roughly 36 by 24 millimeters, the same size as a frame of 35mm film. APS-C is smaller, about 22 by 15 millimeters depending on the brand, with a crop factor of roughly 1.5x. Micro Four Thirds is about 17 by 13 millimeters, with a 2x crop factor. Medium format sensors are larger than full frame and are found in high-end studio cameras.

Sensor size directly affects field of view. A 50mm lens on a full frame camera gives a natural, standard view. Put that same lens on an APS-C camera and it behaves like a 75mm lens because the smaller sensor only captures the center of the image circle. This is called the crop factor. It means lenses are effectively longer on smaller sensors, which can be an advantage for telephoto work but a disadvantage for wide-angle shooting.

Larger sensors also give you more control over depth of field. At the same aperture and framing, a full frame camera will produce shallower depth of field than an APS-C camera. This is why portraits taken with full frame cameras have that smooth, creamy background blur. If you want that look, larger sensors make it easier to achieve. If you want everything in focus, like in landscape photography, a smaller sensor can actually help.

The trade-off is size, weight, and cost. Full frame cameras and lenses are bigger, heavier, and more expensive than their APS-C counterparts. Micro Four Thirds systems are compact and lightweight, making them ideal for travel. You do not need a full frame camera to take great photos. Many award-winning images were shot on APS-C or even smaller sensors. The best sensor size is the one that fits your needs, your budget, and your willingness to carry the gear.