Not many people think about the size of the sensor in the camera they’re about to buy. Lenses, yes, array of settings and flexibility in shooting situations, sure – but not the sensor size. That’s a shame, because the size of the camera sensor changes how each of these components works in capturing an image.
Does camera sensor size matter? The short answer is probably. That is because the smaller the sensor, the less light it captures. However, other aspects such as the number of megapixels on the sensor and the type of lens matter just as much.
Understanding how the sensor size affects your photo taking gives you an advantage. You can then compensate for some aspects of change. All other things being equal, a full frame and a smaller sensor can both take awesome shots of the same subject.
What is sensor size?
It helps to understand the types of sensors in the typical camera purchased by enthusiasts and serious hobbyists. The best way is often to compare them in reference to one another.
Take a look at this graphic with its layers of relative sensor sizes. These are also the typical camera manufacturers using them.
Unfortunately, the names of image sensor sizes are not intuitive. Medium format, the size of the outermost frame, is actually a bigger medium format (digital or film) camera.
On the other hand, the smallest box is for ‘pocket’ cameras. However, those aren’t the same as the point-and-shoot you put in your pocket.
Perhaps the most important things to notice occur in the middle of the graphic. That is where you see 35mm “full frame” and the various APS sizes. That’s where the magic happens for most of us. Those are the most common sensors in our everyday cameras.
How do I know the size of my sensor?
The size of your image sensor will be included on the specifications for the camera and listed in the description online. It’s usually titled something like “CMOS” (referring to the type of electronics running it). Sometimes it includes the millimeter size of the sensor, such as “23.5 x 15.5mm”, or the name of that size, APS-C.
With knowledge of the size comes power. Check out these three cameras to test your ability to find out what size the sensor is:
What does the image sensor do?
The sensor captures the image made up of light that travels through the lens. For a single-lens reflex (SLR) camera, it shines on a mirror that is exposed when you depress the shutter release, and that bounces on to the sensor. For mirrorless cameras, the image travels right to the sensor without the bounce.
Film cameras only have one sensor size, 35mm, because they bounce the image or shine the image on a set size of film. All other sensors are sized as some fraction of that 35mm “full frame”. (We’re ignoring medium and large format cameras. Those are few and probably not what most of us as enthusiasts or prosumers are buying.)
APS-C or -H sensors and all others are smaller. The relative size is based on the diagonal distance between far corners, called the “crop factor”. Here’s a chart showing you the crop factors of common sensors, along with examples of the cameras you’ll find them in.
|Sensor Size||In millimeters||Crop Factor||Camera Examples|
|Full frame||36 x 24mm||1.0||Sony A7R III,Pentax K-1|
|APS-H||27.9 x 18.6mm||1.5||Canon 1D MIV,Sigma Quattro H|
|APS-C||23.6 x 15.6mm||1.6||Nikon D500,Canon EOS 80D|
|Four thirds||17.3 x 13mm||2.0||Olympus EM-1 II,Panasonic G9|
|1” (and smaller)||12.8 x 9.6mm||2.7||Panasonic FZ2500,Nikon 1 V3,Fujifilm X30|
Note: Anything 1” type and smaller is known as “small sensor” and is the kind you would find in truly inexpensive pocket-style cameras.
Do the megapixels of the sensor matter?
Yes, the number of megapixels matter in terms of sharpness and resolution of your image. The most you’ll find in any camera is 51MP (51 million megapixels) in the Fujifilm GFX 50S, the Pentax 645Z, and the Hasselblad X1D (medium format sensors); and the Canon 5DS or Canon 5DS R (full frame sensors). The Nikon D850 scores a whopping 46MP on its full frame sensor too.
On the other hand, the APS-C you’d find at a big box store is no slouch either. A Nikon D7500 has a 20.9MP sensor, and a Canon EOS M50 has 24.1MP. Both of these do a fine job with both low light and fast action shooting.
One trade-off to having more pixels is electronic file size. The more MPs you have, the more bytes of data you’re saving in the file for that image. That means you’ll use up your memory card faster.
More pixels on a smaller sensor isn’t necessarily good, though, since they are crammed closer together. That’s known to negatively impact the sharpness you were seeking in the first place.
How does the sensor change my lens choices?
Lenses are labeled by focal length, like a 50mm prime or 18-105mm zoom. This is the viewing angle of the lens, a measure of distance from the sensor through the lens. If you’re using a full frame camera, everything in that angle of view can become a pixel in your image.
Say, though, that you’re using an APS-C sensor camera with a 1.6 crop factor. That means the sensor is smaller, and that changes the equivalent focal length (the effective one, not the real one in the lens) since everything is compressed to fit into a smaller sensor. In other words, it’s going to act like you’re shooting with a higher focal length lens.
Confused? Don’t be – and don’t feel you need to understand this completely, either. What you need to know is that if you’re shooting with any sensor smaller than full frame, you need to consider your choices of lenses. Here are some examples.
|Sensor Size||Crop Factor||Lens Example||Equivalent Focal Length|
|Full frame||1.0||Canon EF 50mm f/1.2L USM||50mm (crop factor of 1.0 times 50mm)|
|APS-H||1.5||Canon EF 100-400mm f/4.5-5.6L IS II USM||150-600mm (100*1.5 – 400*1.5)|
|APS-C||1.6||Nikon 1 Nikkor 10mm f2.8||16mm (10*1.6)|
Does the aperture size, the f-stop number, matter?
No, the aperture does not make any difference to how your sensor works. It changes the properties of your image and your shutter speed. However, that’s for another article.
Is a bigger sensor better?
No, not really. Many professional photogs win awards with APS-C cameras. Some even do so with small sensors.
What wins the awards (or the accolades of your friends and family) is your framing of an interesting subject in a way that tells a story.
That being said, some will say a full frame camera is the only way to go. That is because of the image clarity and sharpness assumed to go with a full frame space.
The lens focal length and sensor resolution in megapixels have such a huge impact. So that’s only partly true.
How do you choose the best sensor type for your shooting?
What are your goals for your images? If it’s gallery-level fine art, spend the big bucks on a camera with a full frame sensor. While you’re at it, invest in professional quality lenses across a spectrum of focal lengths for the types of subjects you like to shoot.
If your photos are destined for blog post images, you’ll do well with an APS-C or -H camera. The only caveat is if you’re shooting most of the time in very low light conditions, where you might not get the quality or range you like with the smaller sensor.
Let’s say all you want to do is post your pics on social media or put together a vacation slideshow for family and friends. Your sensor won’t matter as much as the overall ease of use of the camera. Even reasonably priced point-and-shoots, like the Canon G16 or the Nikon P7800, take terrific photos.
Can you sum this up for me?
Remember three things when you think about your camera choices based on sensor size:
- Sensor size matters in terms of megapixels to capture more sharpness in the image.
- Sensor size can change the equivalent focal length of a lens if you’re shooting with anything smaller than a full frame sensor.
- Maximizing the sensor size matters most if you’re shooting in very low light conditions, you need high levels of detail in very fast shooting, or you want to enlarge the photos to larger-than-life size with fine detailing.
Most of all, though, the quality of the photos you take depends on you. If you know how to adjust for a smaller sensor, both in your gear and in your shooting style, you can make magic happen, and size truly won’t matter.Back to Top