The Different Camera Sensors – A Practical Guide

Essential part of your camera, the image sensor is the key to accurately capturing a scene as an image. In other words, it’s a crucial factor when choosing your camera body!
Its size and technology will vary depending on the type of camera you’re going to buy: DSLR, mirrorless, compact… or even medium format for those with a bigger budget.
How do you choose the sensor that best suits your needs? Our guide covers everything you need to know about the different types of camera sensors in 2025.

Table of contents

1. Why is the sensor so important in photography?
2. What is a camera sensor and how does it work?
3. The different sizes: full-frame, APS-C, Micro Four Thirds, one inch, medium format
4. Sensor types: CMOS vs CCD
5. Styles, shooting conditions and situations where the sensor matters
6. Which one to choose as a beginner learning photography?
7. Practical tips
8. Frequently Asked Questions

Why is the sensor so important in photography?

The size and type of sensor have a significant impact on performance and, by extension, the final result. This effect is noticeable both in technical terms (presence or absence of digital noise, level of detail) and in terms of aesthetic rendering (bokeh, depth of field).

ISO sensitivity and noise

A larger sensor offers better digital noise control when using high ISO sensitivity in low light. At the same ISO setting (for example, 3200), you’ll get less noise with a full-frame sensor than with a Micro Four Thirds sensor.

Depth of field

The larger the sensor, the shallower the depth of field at the same aperture. In other words, it’s “easier” to isolate your subject from the background with a large sensor, which is why it’s commonly used in portrait photography.

Dynamic range and post-processing

A full-frame sensor retains more detail in highlights and shadows, giving it a wider dynamic range. This makes it easier to recover these elements in post-production.

Field of view and focal length equivalence

Sensors smaller than full-frame (such as APS-C, one inch, and Micro Four Thirds) crop the image and apply a multiplication factor to the lens’s focal length. This factor is usually around 1.5 to 1.6 depending on the manufacturer for an APS-C sensor. For example, this means that a 50mm lens on a Canon APS-C camera gives the same zoom level and field of view as an 80mm lens on a full-frame camera.

What is a camera sensor and how does it work ?

The sensor is the component of the camera responsible for capturing (hence the name) the photographed scene.
Its cells receive light signals and convert them into electrical signals.
This information is then saved as a file on the camera’s memory card.
The most important part of this component is its photosensitive surface.
This surface is covered with various layers, the most important for us as photographers being the photosites and the Bayer filter.
Combined, these two layers work a bit like the rods and cones in the human eye, complementing each other and allowing our brain to reconstruct an image.

Photosites

Photosites are the elements we refer to when we talk about the number of pixels in a camera sensor.
To be precise, we should talk about “effective pixels” – that is, those actually present on the sensor.
The role of these cells is to convert light into electrical charge.
The electrical signal sent by the photosite is proportional to the amount of light received, which then makes it possible to “redraw” the image in the file generated by your camera.
Note that sensors/photosites only capture light – that is, shades of grey.
To capture colour, another layer must be added – the Bayer filter.

The Bayer filter

To obtain colour, the sensor has a dedicated layer made up of a system of red, green, or blue filters placed over each pixel.
This is known as the Bayer filter.
This mosaic of coloured filters ensures that each photosite receives only one primary colour (red, green, or blue).
The camera’s processor then reconstructs the full colours of the image, with all their nuances, by combining the information from neighbouring photosites.

The different sizes: full-frame, APS-C, Micro Four Thirds, one inch, medium format

The physical size of the sensor varies depending on the type (compact, DSLR, mirrorless…), model, and price range of your camera.
It has a direct impact on the quality of the image produced.
For professional photographers and photography students, the three formats that interest us most, from smallest to largest, are: APS-C, full-frame, and medium format.
Other smaller formats also exist, such as one inch or Micro Four Thirds, but these are generally used only in “consumer” devices like compacts, bridge cameras, or smartphones.

APS-C – 24×16 mm

Depending on the manufacturer, APS-C sensors are around 1.5 to 1.6 times smaller than full-frame sensors.
For example, Canon uses APS-C sensors measuring 22.2×14.8 mm (1.6x crop factor), while Nikon, Sony, and Fujifilm use a 23.6×15.6 mm format (1.5x crop factor).
This more compact sensor format was created purely for economic reasons.
APS-C offers a compromise between high image quality and lower production costs compared to full-frame sensors.
APS-C is the most common sensor size for entry-level and enthusiast DSLR and mirrorless cameras.
It is found, for instance, in the Canon EOS Rebel T100, Nikon D3500, and Sony A6100.

Full-frame – 24×36 mm

Interestingly, full-frame is a historical reference to the film used in analogue cameras.
A full-frame sensor is simply one that matches the size of a 35mm film frame… that is, 24mm by 36mm.
Professional and semi-professional cameras like the Canon EOS 5D Mark IV or Nikon D850 use this format.
The larger photosensitive surface of a full-frame sensor allows it to:

• capture more light
• achieve very high resolution (30–50 MP)
• better handle digital noise in low-light conditions
• offer a wider dynamic range

The downside is the cost and size: full-frame bodies and lenses are heavier and often more expensive.

Medium format – 30×40mm or more

The medium format sensor is larger than the 24×36 mm full-frame and represents the largest sensor size available in a digital camera.
The dimensions of medium format sensors vary but are often around 44×33 mm, or even 53×40 mm for the largest models.
This format offers many advantages (image quality, high dynamic range, more pronounced depth of field) but also comes with significant drawbacks.
The biggest one is undoubtedly the price – for instance, expect to pay around 5,500 euros for the FUJIFILM GFX100S II (body only), which is actually a reasonable price for a medium format camera.

It’s also worth noting that medium format bodies are quite bulky and heavy (due to the sensor size).
The shooting speed is generally slower than with smaller formats.
This explains why medium format cameras are typically used for genres that don’t require rapid burst shooting, such as landscape or fashion photography.

Micro 4/3 and one inch

The 4/3 format was invented by Panasonic and Olympus and is roughly half the surface area of a full-frame sensor.
The one-inch format, on the other hand, measures about 13×9 mm.
These formats are found in many compact and bridge cameras, as well as in smartphones.

Sensor types: CMOS vs CCD

CMOS sensor (Complementary Metal-Oxide Semiconductor)

Also known as a complementary metal-oxide-semiconductor sensor (hence the acronym CMOS for Complementary Metal-Oxide-Semiconductor), the CMOS is the most widely used today, and equips virtually all devices currently produced. Its low cost, low power consumption and fast readout capabilities have made it the absolute standard.

CCD sensor (Charge-Coupled Device)

Also known in proper English as a charge-coupled device sensor, the CCD sensor was the standard for the first digital cameras that appeared in the 1990s.

Situations where your sensor matters

The sensor will in fact have little impact on the final image quality in most conventional situations – that is, good lighting and a stationary or slow-moving subject. This is why smartphone manufacturers can sometimes boast of achieving professional-quality photos. If you’re shooting in soft light with limited brightness differences between the light and dark areas of the scene, you’ll notice little to no difference, even between a full-frame sensor and a one-inch sensor.

However, sensor size becomes extremely important if you’re shooting in complex situations such as those listed below.

Very low light/ Night photography

This is where full-frame really comes into its own, with its larger surface area and bigger pixels providing better ISO performance. In simple terms, the larger the sensor, the less grain you’ll have in low light.

High-contrast scenes (landscape, architecture)

High contrast implies a wide gap between the darkest and brightest areas in the photo, which corresponds to the sensor’s dynamic range. As a general rule, full-frame offers the widest dynamic range, allowing it to retain the most detail in highlights and shadows, even in highly contrasted images. This will make your editing/post-production work much easier.

Outdoor portrait

Bokeh, or background blur, is generally of better quality with larger sensors. This becomes particularly important when taking portraits with a complex background (for example in a forest, a meadow, etc.) because you’ll want to isolate your subject from the blurry background. You’ll get a smoother and more “creamy” bokeh with a full-frame than with an APS-C sensor.

Which sensor to choose when Sstarting out in photography?

If you’re new to photography and don’t know which camera to choose, an APS-C digital SLR is probably the best balance between budget and performance. Entry-level DSLR models like the Canon EOS 250D or the Nikon D3500 feature a 24 MP APS-C sensor and offer the same basic functions as a pro body (automatic modes, 18–55 mm kit zoom, optical viewfinder).

Pro tips

Forget about the number of megapixels

Contrary to popular belief, a 50-megapixel sensor doesn’t add much in most cases (much to the displeasure of iPhone owners). A 20 to 24-megapixel sensor is more than enough for amateur use. More important than the number of pixels here is the sensor size and the performance level of the pixels.

Keep ISO sensitivity as low as possible

The best image quality is generally found at ISO 100–200, regardless of your sensor. So try to adjust your exposure settings (shutter speed and aperture) to keep your ISO as low as possible. You can also use a tripod to reduce the risk of camera shake and lower your shutter speed further. Note that while the ideal is to stay close to ISO 100, most APS-C cameras generally deliver quite acceptable image quality up to 1600 or even 3200 ISO.

If you have an APS-C, take advantage of the crop factor

If you have an APS-C or Micro Four Thirds camera and full-frame lenses, take advantage of the crop factor.

Remember to shoot in RAW format

Whatever sensor your camera has, saving your images in raw format (in other words, “RAW”) will allow you to maximise the quality of the photo and give you more flexibility in post-production.

Don’t rely too much on the sensor’s capabilities

Frequently Asked Questions

What is a camera sensor?

Found in every digital camera or smartphone, the camera sensor is the electronic component responsible for capturing the light coming from the photographed scene. It converts light into electrical signals which are then transformed into digital data to be stored on the device’s memory card. It replaces the film of traditional cameras.

What is the role of a camera sensor?

The camera sensor transforms the light received through the lens into electrical signals, which are then converted into a digital image. It consists of various elements, notably photosites that capture light intensity, and the Bayer filter array that captures colour information.

What types of sensors are there?

CMOS (Complementary Metal-Oxide Semiconductor): used in most modern devices. Faster and less expensive than CCD.
CCD (Charge-Coupled Device): very good image quality but power-hungry.

Which sensor provides the best image?

Medium format sensors offer the best image quality thanks to their large surface area, noise handling, and depth of field. However, they are very expensive (often over 5000 euros). The full-frame sensor is an excellent choice for most photographers, while the APS-C sensor remains a very viable alternative with very good image quality.

What is the advantage of having a large camera sensor?

A large sensor captures more light, which improves image quality, reduces digital noise, offers a wider dynamic range (better detail in dark and bright areas), and enhances depth of field/bokeh.

What is the Bayer filter/matrix?

The Bayer filter array is a system of RGB (Red, Green, Blue) colour filters placed over the pixels (photosites) to enable the reconstruction of the colours in the digital image.

What is a sensor’s dynamic range?

Dynamic range refers to the sensor’s ability to capture detail in highlights and very dark areas. The larger it is, the better the exposure in high-contrast scenes. It directly depends on the sensor size. For example, a smartphone typically has a dynamic range of 8 EV, an APS-C sensor 10 to 12 EV, and a full-frame can reach 15 EV.

Is the number of megapixels important?

The number of megapixels is not the sole criterion for image quality. The size of the photosites (actual pixels on the sensor) is just as important. A 20 MP APS-C sensor in a DSLR can perform better than a 50 MP 1-inch sensor in a smartphone.