Understanding Camera Sensor Size (And Why It Matters!)

By Hillary Grigonis

Related course: Photography for Beginners

Camera sensor size can help you predict image quality before a camera even comes out of the box.
A camera’s sensor is the part of the camera actually capturing the image. It plays a big role in what the resulting image looks like.
But what does camera sensor size mean? And why does it matter?
Understand when you need a bigger camera sensor — and when you don’t — in this beginner’s guide.

Camera sensor size plays a major role in image quality. Image by Alexander Andrews.

Camera Sensor Sizes Explained

The camera sensor is like a single exposure of film. It can be used over and over again. Just like photography film comes in different sizes, digital cameras have different sensor sizes.
In a digital camera, the sensor is like a solar panel that gathers the light to create an image. A larger camera sensor will gather more light, creating a better image overall.
Camera sensor sizes are standardized. This makes it easy to compare the size of the sensor in one camera to the size of the sensor in another.
There is some variation, Canon’s APS-C is smaller, for example. But the variations are slight enough not to make a noticeable difference in the final image.
Excluding the expensive medium format digital camera, the standard camera sensor sizes are:

A camera sensor size chart

• Full frame: A full frame sensor is based on the size of 35mm film, measuring around 36 by 24mm. Full frame sensors are found in professional level DSLRs and mirrorless cameras. Some very high-end compact cameras also have it.
• APS-C: An APS-C sensor crops the full frame image by about 1.5x, measuring around 22 by 15mm. This is the size sensor found in most entry-level to mid-level DSLRs. Some mirrorless cameras such as Fujifilm’s, and sometimes a high-end compact camera also have it.
• Micro Four Thirds: The Micro Four Thirds sensor camera launched with the start of the mirrorless camera. It was to find a happy medium between camera size and image quality. The Micro Four Thirds sensor has a 2x crop compared to a full frame sensor, measuring 17.3 by 13mm. Olympus mirrorless cameras use a Micro Four Thirds sensor. So do most Panasonic mirrorless cameras.
• One inch: Designed for compact cameras, the one-inch camera sensor measures about 13.2 by 8.8 mm, with a 2.7x crop from full frame. A one-inch sensor is found in a high-end compact camera. It packs more quality than a compact camera, but not as much as a DSLR or mirrorless camera.
• Compact camera and smartphone sensor sizes: The sensors in typical compact cameras and smartphones have more variation. All of them are small considering the size of a full frame sensor. A 1/2.3-inch sensor is one of the most popular sizes, along with sizes like a 1/1.7-inch.

Cameras with a sensor smaller than full frame have what’s called a crop factor. Because the camera sensor is smaller, the image is cropped in closer.
Full-frame sensors offer the most quality. But there are a few perks to picking up a camera with a smaller sensor.
So what are the pros and cons of going with a large sensor compared to a small one?

The Pros and Cons of a Large Camera Sensor Size

Larger Camera Sensors Have Better Image Quality

Camera sensor size is one of the biggest indicators of image quality. Other influencing factors are the number of megapixels, the design of the camera sensor, and the camera’s processor.
Larger camera sensors capture images with more light, less noise, more detail, and more of that beautiful background blur, to name a few.
When comparing two cameras, if one has a larger sensor, that one will have better image quality.

Larger Camera Sensors Gather More Light

One of the reasons larger camera sensors mean a better image has to do with light. The larger the surface area of the sensor is, the more light it can gather in a single shot.
Larger camera sensors are excellent for low light photography for that reason. A larger camera sensor can gather more light even with the same shutter speed and aperture.
That’s why they tend to do better at any type of shot where the lighting is limited. For example, photographing a night landscape or photographing a theatre production, concert, or dark dance floor.

Larger Camera Sensors Handle High Megapixel Counts Better, With Less Noise

Camera sensor size and megapixel count go hand-in-hand. But a higher megapixel count is always better on a larger camera sensor than on a smaller one.
A 50-megapixel full frame sensor will have larger pixels than a 50-megapixel APS-C sensor. Those megapixels have more room on that larger sensor.
That’s why it’s much easier to find a 50-megapixel full-frame sensor than it is to find a 50-megapixel APS-C sensor.
More megapixels create a higher-resolution image with more details. But, trying to fit a lot of megapixels on a smaller sensor creates problems when it comes to low light photography. Those pixels are so small.
A small sensor with 25 megapixels will have more noise or grain at high ISOs than a full frame sensor with 25 megapixels.

Larger Camera Sensors Create More Background Blur

Ever wonder why you can’t get that nice soft background blur from your smartphone? Larger camera sensors make that nice soft background easier to attain. This is near impossible with a smaller sensor.
That’s why smartphone companies are faking background blur using artificial intelligence in portrait mode. The sensors are just too small for the real thing.
If you want that soft background blur or narrow depth of field, you want a full frame camera with a wide aperture lens.
Larger camera sensor sizes create more background blur in a number of different ways. The larger sensor size increases background blur due to the enlargement factor.
Larger sensors don’t crop the image. Photographers will also tend to get closer to the subject, which will also increase background blur.

Smaller Camera Sensors Allow for Better Zooms

Full frame cameras may take the cake when it comes to image quality and background blur. But if you want to get up close, a smaller sensor has a few perks.
The camera sensor’s crop factor means smaller sensors make it easy to get up close to the subject. Zoom lenses are also smaller and cheaper when designed for smaller sensor cameras.
For example, the Micro Four Thirds sensor has a 2x crop factor. That means a 300mm lens is really a 600mm lens.
One of the biggest perks to a smaller sensor is that it’s easier to get up close. Without carrying around a huge, $10,000 600mm full frame lens.
That’s a big consideration for photographers that can’t move closer to the subject. This includes wildlife photographers and sports photographers.

Smaller Camera Sensors Mean Smaller Cameras Overall

If the camera sensor is smaller, in general, the entire camera will also be smaller. That’s not true 100 percent of the time (like with the large Micro Four Thirds Olympus OM-D E-M1X).
But most of the time, smaller sensor cameras weigh less and are more compact.
If you want a good travel camera, a smaller sensor camera may be easier to pack. The growth of mirrorless camera changes this some.
It’s now easier to find a compact full frame camera than ever before. But most Micro Four Thirds and APS-C mirrorless cameras are still more compact.
The bigger reason that smaller sensors mean smaller camera systems is that the lenses are smaller. You can pack a 150mm lens to get the reach of a large 300mm lens on a Micro Four Thirds system, for example.
The perk is with the biggest telephoto lenses, the wide angle lenses won’t offer much of a difference.

Smaller Camera Sensors Are More Budget-Friendly

One of the biggest reasons to skip the full frame? The cost. Most full-frame cameras are professional-level gear.
Entry-level full frames can be picked up for around $1,200 to $1,500. But many are $2,000, $3,000 and even higher.
Photographers on a budget can get most of the same perks by choosing a mid-sized sensor. Sure, an APS-C sensor isn’t quite as good as a full frame sensor. But it is way ahead of smartphones and compact cameras.
The entry-level options can be picked up for a few hundred dollars instead of a few thousand.
Some smaller sensor cameras are able to pack in more high-end features without getting too crazy with the price point.
Finding advanced features like 4K video and in-body image stabilization for under $1,500 is often easier with a Micro Four Thirds camera system.

Camera sensor size is the biggest indicator of image quality. It’s also important to note that it’s not the only quality indicator. More megapixels will increase detail (but also tend to decrease low light quality).
A backlit sensor is also better than a sensor of the same size that’s not backlit. The camera’s processor or built-in computer handling those images also play a role in image quality. Newer processors tend to produce less grain on the image than older processors.
The lens plays a role in image quality as well. Whether that lens is attached to the camera or interchangeable.
Larger camera sensors capture better images. This is especially true in low light, with more background blur and the potential for fitting in more megapixels.
Smaller camera sensors, meanwhile, offer more zoom, smaller overall camera sizes, and lower price points.
So what sensor size is right for you? If you want maximum background blur and the best low light quality, choose a full frame camera.
If you want still great photos on a budget, try an APS-C camera. And if you want a travel-friendly interchangeable lens camera or need some serious zoom power, consider a Micro Four Thirds sensor.

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