Understanding Your Camera’s Sensor

The camera sensor is where all the magic happens. The sensor is where the light hits the photosensitive pixels to create and save our images. Each camera has a different size and type of sensor.

The surface of the camera’s sensor is made up of a thousand of photosites. When light hits each one of these photosites, a filter determinate what color the light is, other photosites talk to each other and in a flash work with the CPU in the camera to determinate what color each photosite should be and how light or dark it is based on the settings you have chosen for exposing, then we have a saved image.

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All camera’s sensors aren’t made equally. Different cameras will have different sizes:

  • Full frame (36mm x 24mm). A full frame camera means a sensor is the size of a 35mm frame. 35mm being the size of most common sizes film used in film photography back in the day, this is going to be the biggest and most expensive sensor size in the prosumer camera world.
  • Cropped or APS-C. This sensor is a bit smaller than the full frame and is used in a lot of smaller DSLR and mirrorless cameras. It tends to be a little bit cheaper and generally has less megapixels then a full frame camera.
  • Micro four This is a bit smaller than the APS-C size sensor and is common in companies like Olympus and Panasonic.
  • One inch (1”) or one third sensors are very small and are normally found in point and shoot cameras and cellphones.

There is also a relationship between sensor size and focal length. An easy way to understand this is with a small sensor, such is a cropped sensor, it is literally cropping the image which result in a more telephoto or a zoomed in shoot.

Which one should I choose?

Typically, full frame sensors are used by most professional photographers the reason being that the size of the sensor itself allows for better performance in low light. The larger the sensor, the easier it is for it to collect light. It also helps with the depth of field. The aesthetic of your subject in focus and lots of backgrounds out of focus is archived better with a larger sensor. Finally, if you are planning on printing large photos or cropping in, the larger full frame sensor will allow you to do that more easily without a lot of loss in quality because they use more pixels.

An APS-C sensor is typically cheaper, smaller and light-weight which is why most photographers will choose to use it. It will still produce excellent images although the megapixel is a bit lower. Crop sensors are great for travel and will allow your camera to be smaller, making all the components smaller and easier to care.

The smaller the sensor gets the lower quality and ability to capture in low light will be. This is one of the biggest throwbacks using point-and-shoot and smartphones. Although as technology gets better and better, smartphone sensors have gotten better as well.

Continue to lesson 40: Understanding photo resolution