Camera sensor sizes explained: what you need to know about Four Thirds, 1/1.7, full-frame and APS-C format

Confused about Four Thirds, 1/1.7, full-frame and APS-C format and why it matters? Don't worry, here's everything you need to know about camera sensor sizes.

Camera sensor sizes explained what you need to know about Four Thirds 1 1 7 full frame and APS C format

Sensor size is important in photography because it has an impact upon image quality. If you have two cameras with the same pixel count, but one has a physically larger sensor than the other, the one with the larger sensor will usually produce better quality images.

This is because the photo receptors, which are commonly called pixels these days, are larger on the bigger sensor.

The main purpose of a photo receptor is to receive light and generate an electrical signal that is converted into a digital image signal. The more light that the sensor receives, the stronger the image signal will be.

A strong signal requires less amplification and this means there's less opportunity for image noise to introduced or enhanced.

SEE MORE: Full-frame sensor size explained - how to exploit its advantages and cool effects

A camera's sensor is usually its most expensive component and this means cameras with larger sensors tend to be significantly more expensive than cameras with smaller sensors.

The camera's body also usually needs to be made larger to house the bigger sensor and to accommodate the lenses that are required to produce the larger image circle.

To summarise, in general terms, cameras with larger sensors tend to be bigger and more expensive than those with smaller sensors and they produce better quality images.

Canon EOS 1D X full frame sensor

SEE MORE: Full-frame DSLRs - do you really need one?

Bigger camera sensor or fewer pixels?

As we've already mentioned, having a larger camera sensor allows the pixels to be made bigger and this has positive implications for image quality with noise levels being reduced and dynamic range extended. A similar thing can be achieved by keeping the pixel count down on a smaller sensor.

However, high pixel counts are often seen as a good thing because images are larger and it enables more detail to be recorded.

The challenge for manufacturers is to keep noise levels down and maintain image quality at the higher sensitivity settings when light levels are low.

Some cameras like the Nikon D4S offer superior low light performance by having a relatively low pixel count (16-million in the case of the D4S) and a large (full-frame) sensor.

This makes them very versatile, but the images aren't especially large and those wanting to produce big images with lots of detail should opt for a high pixel count camera such as the Nikon D810, which has 36 million pixels on its full-frame sensor.

This camera is capable of resolving a huge amount of detail, but it's not the best choice for shooting in very low light. It will be interesting to see how the 50-million-pixel Canon EOS 5DS performs when it goes on sale in June this year.

SEE MORE: DSLR vs Mirrorless - understanding the key differences

Full frame vs Crop sensor cameras why crop sensors keep more in focus

What size is it?

Full-frame cameras are called such because they have a sensor that's the same size as a frame of 35mm film (26x24mm). APS-C format cameras are called that because their sensor is approximately the same size as the Classic format on the smaller APS-C format film.

These sensors typically measure 23.6x15.7mm in Nikon, Pentax and Sony cameras or 22.2x14.8mm in Canon cameras. Micro Four Thirds cameras use a smaller sensor which measures 17.3x13mm.

The size of the sensor inside many pact cameras and some compact system cameras is often given in imperial measurements that are based upon a system that was used for old television cameras.

This uses fractions which confuses things a little and manufacturers are often rather cagey about giving actual dimensions.