Relative sizes of digital camera sensors - Graphic courtesy of Cambridge in Colour*
The size of a camera sensor will have a big impact on the quality of your pictures. The lens gathers light and directs it towards the sensor, and the sensor records the light to create the image.
Large sensor produces better images
All things being equal, a larger sensor will receive more light than a smaller one, and produce better images. This is especially important in low light photography.
When light levels are low, a smaller sensor will generate a higher amount of noise, which will decrease the quality of the images. This is why the best low-light setups include a camera with a large sensor (usually a DSLR) and a lens with a large aperture.
Compact digital camera sensors
In the compact world, most sensors are equivalent in size. Sensor size for compacts is calculated by measuring the size of the sensor’s diagonal. The most common sizes are 1/2.5 (0.4) and 1/2.3 (0.43) inches. Pretty small by all accounts!
Some manufacturers, however, have started including larger sensors in some of their compacts. For instance, Canon’s s90 camera has a 1/1.7 (0.58) niches sensor. This represents a total area 37% larger than most comparable models, and yields much better low light pictures.
Pixel density
One thing to keep in mind is that the size of each individual pixel is what will truly define the performances of the sensor. In other words, more pixels over the same area means that noise levels will increase, because each individual pixel will receive less light.
DSLR sensors
The sensor in a typical digital single lens reflex camera is many, many times larger than the sensors found in compacts. This means that DSLRs are much better at taking low-light pictures with low noise. But even in the DSLR world, there are differences between sensors.
The larger sensors are called “full-frame” and are found in some higher-end, professional bodies. The size of these sensors is equal to that of 35 mm film, with a 1.7 inches long diagonal.
The vast majority of DSLRs have sensors slightly smaller called APS, with a 1.18 inches diagonal (48% of the area of the full frame sensor). The use of the APS sensor allows smaller lenses to be designed while still preserving most of the optical performances of the sensor.
Another sensor size used in DSLRs is called Four Thirds (0.85 inches diagonal). This system, while being slightly less efficient in low light, makes possible the use of extremely small lenses. This sensor size is also used in the “micro Four Thirds” system, which is a bridge between compacts and DSLRs.
Visit our Amazon shop for a list of compact digital cameras with larger sensors
It’s not only recently that some compacts have had 1/1.7″ sensors. My first digital camera, bought in 2002, is a Fuji 4800 and it has one. 3 years ago I bought a Sony H2, and assumed it would be better in every way. However, I noticed that at 400 ASA photos on the Fuji have less noise.
Another advantage of a larger sensor is that you can throw backgrounds out of focus. I don’t want to go back to the days of a heavy SLR with extra lenses, but I would like a camera with a decent zoom, large sensor and a hot shoe that’s not too expensive. Perhaps one of these new micro four thirds will eventually suit.
Danny, you are correct that larger sensors existed in the past. There have been a few years when they were all but absent, and now they are beginning to appear again. I did not want to go into to much history in this short article.
You are also correct that a larger sensor will help isolate subject from background, but only indirectly. The sensor itself has no impact on this, however a larger sensor will allow the use of a longer focal length to obtain a given field of view, and a longer focal length helps diminish the depth of field.
Thanks for a very helpful article. Only started to learn about sensor size as i am finding my compact digital camera has very poor indoor performance. So I am on the look for a better performing camera.
To tap into your expertise, it would help people like me to narrow the search down if could add a list of cameras and their sensor size.
Thanks again.
Glad you found the article helpful. To check the size of a sensor before buying, check out the digital camera database at dpreview. We also have some listed in our Amazon shop.
For compact cameras i think Dlux 5 has the best point and shoot sensor! I love that camera.
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