The terminology scares, sometimes. It throws us back so much technicality right? But one of the missions of this blog, if not the most important, is to disseminate photographic knowledge and democratize photography among all readers of it. A theme that is often pushed back by its apparent complexity is the sensor issue. Fake friend. It is not a complex issue at all, quite the opposite. And although it is not serious to ignore some photography concepts, it turns out that the sensor is a key piece in a camera. In this article today I will talk about this "vital organ" called a sensor. If you are about to buy your next camera you need to know what the sensor is, so you will make a good choice. If you already have a camera you should also find out about the sensor inside it.


No matter whether it is reflex or compact, the sensor is the heart of our camera , the goal. Everything we do to capture a good photo, from the moment we frame until the moment of shooting, all are actions and steps that pursue a single purpose: to drive the exterior light (image) towards the camera sensor . The sensor as its name implies is a "sensitive" element within our camera, that on which the light is projected drawing an image that represents what our camera sees. The sensor is for digital cameras like the film or reel that we used in analog cameras. The difference is that in analog cameras the film had to be changed while in digital cameras the sensor is fixed and does not need to be changed. We can "project" on it as many digital photos as we want, because to store the photo we already have the memory card.


If you're curious to know what the sensor of your quiet camera is composed of, you don't need to break it to find out. That's what I'm for. Well, your camera's sensor is a kind of small chip made up of millions of light-sensitive components, called pixels. Those millions of pixels must always be dark, and as soon as they are exposed to light they capture it, so they are sensitive. Thanks to that capturing that light, we get the image.


The sensors can be classified according to their technology, and that of your camera probably belongs to one of the following types of sensors:
  • CCD and Super CCD
  • CMOS
  • Foveon X3
Although in reality the 2 types of sensors more expanded or popular are the CCD and CMOS . I don't want to mistreat you with a series of technical specifications about each of these formats, because I think they will be irrelevant. What you should know is that the sensors of the CCD type were the first to be used, but currently most cameras are using CMOS sensors. As it was discovered that this new technology called CMOS allowed the creation of sensors that consumed much less battery, and at the same time allowed much faster image processing. On the other hand, factories find it much cheaper to manufacture a CMOS sensor than a CCD. As for image quality, in the past CCDs offered better image quality, but over time the CMOS already reached that quality.


Yes. It matters a lot. When I go to buy a digital camera, either SLR or compact, the first thing I see is the size of the sensor. He will determine the quality of the camera and therefore that of the photos. To avoid messing with terminology and abstract explanations, here is the list of the most common sensor sizes. They are ordered from the largest to the smallest. The rule I want you to remember forever is easy: the larger the sensor size, the better.
  • Full Frame sensor , also known as 35mm sensor. Dimensions: 36x24mm
  • Sensor APS-H . Dimensions: 28.7x19mm
  • APS-C sensor (used in Nikon, Pentax and Sony). Dimensions: 23.6 × 15.7mm
  • APS-C sensor (used in Canon). Dimensions: 22.2 × 14.8mm
  • Sensor Foveon (Sigma used in cameras). Dimensions: 20.7 × 13.8mm
  • Micro Four Thirds Sensor . Dimensions: 17,3x13mm
  • [... other smaller sensors ...]
Update: Very aptly Álvaro asks me (below in the comments) that if the sensor size is specified in the compact cameras. Here I recommend the following: try to find out the size of the sensor in the camera case, if it does not come try to see it in the description of the camera on the website of the store (for example, Fnac.es), if it does not come either I recommend there search on specialized websites where all the camera features come. A good Web for this effect is the famous dpreview where they analyze in detail any camera indicating almost always the size of its sensor. On the other hand, in terms of compact digital camera sizes there are usually 3 sizes that are the most expanded and are the following, from highest to lowest:
  • 1 / 1.7 ? (7.6 x 5.7mm)
  • 1 / 1.8 ? (7.18 x 5.32 mm)
  • 1 / 2.5 ? (5.76 x 4.29 mm)
I hope this info works. Note: You should know that the sensor size affects, in addition to the image quality, the focal length of the lens. When we buy a lens for example of 18-55mm and we use it at 18mm, it's really only 18mm if we have a Full Frame Sensor (the first one from the list above, the big one). If the sensor is smaller then the real focal length will not be 18mm but greater, maybe 27mm or so, and so we go, the smaller the sensor, the greater the real focal length we will get. This is an inconvenience if we are looking for a wide-angle photograph, but it is an advantage if what we want is a huge zoom telephoto lens. Well with a 200mm we would get almost 300mm real.
Comparison between sensor sizes


I have left them for last because I think they are given more importance than they should, however if we want to be fair I can not exclude them from this article: the number of megapixels and ISO sensitivity are also two important factors in a sensor of camera In theory, the more megapixels our sensor has, the better image quality we will get. This is not always absolute so do not rush buying a camera just because it has more megapixels, although it is a factor to consider. The other factor of importance is the ISO sensitivity. This indicator reveals the degree of sensitivity of the sensor to light. For example, shooting a photo at ISO 200 will capture twice as much light as shooting at ISO 100. Although it is known that the more ISO sensitivity, the more noise we will have in the photo, so be careful. This is all regarding the subject of sensors. Everything you have to know about the sensors now you know. As always, I hope you enjoyed this article. If you consider it useful and want to share what you have learned with other readers please do not hesitate to vote it or recommend it with the buttons below. I will be very grateful

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