015 - Fundamentals of Photography: What is Sensor Size & Why Does it Matter?
When you are choosing which camera to purchase, you are going to hear about sensor size. It’s an important distinction between different types of cameras. Now, there isn’t one ‘right’ and one ‘wrong’ sensor size. Every sensor has various advantages and disadvantages to it. Yes, even the venerable full-frame has downsides to it. So, how do sensors affect the pictures you are going to take? And which sensor is the right one for you to choose? Those are questions you should be able to answer at the end of this episode.
When you hear someone talk about a type of sensor they are talking about the size of the sensor and the qualities that go along with that size. There are four sensors we are going to talk about today. In order of smallest to biggest they are:
Four Thirds
APS-C
Full Frame
Medium Format
Full frame sensors are considered the standard in photography today. They are based on the 35mm film size and are the reference point for lens focal length and aperture. So, with that in mind, we are going to talk about each one of these sensors in reference to the size of a full-frame sensor.
Common Misconceptions
Firstly, full-frame sensors don’t inherently offer better image quality. You won’t magically get better images just by buying a full-frame camera. In the hands of a capable professional, you can create amazing photos with any type of camera or sensor.
Just because four-thirds isn’t as big as a full-frame sensor doesn’t mean it produces worse images. It produces different photos. And each sensor has its unique properties and things that it does very well.
Secondly, megapixels. Do more megapixels make that much of a difference in photography?
The answer is yes, and no. It really depends on what you are shooting. Megapixels are not the be-all and end-all for the quality of a sensor. It’s just another measure of what that sensor is meant to do. Other aspects, like low-light performance, dynamic range, and frames per second, are just as important to consider. So don’t assume that only because a camera has a lot of megapixels that it will automatically produce good images. Conversely, don’t assume that just because a camera has low megapixels that it won’t produce stunning photos.
Megapixels start to make a difference when you are producing images that need to be heavily cropped, as you will have more data to work with, and when you will be creating huge, detailed prints.
Some Terms
Field of view, or angle of view, is how much of your scene you will be able to see and record in your camera. On a smaller sensor, your angle of view is tighter as well. This is why, when you are looking at lenses made for smaller sensor sizes (such as micro four-thirds lenses), you will see a 35mm equivalence. This is because a 35mm focal length on a micro four-thirds camera is not the same as a 35mm lens on a full-frame camera. Because of the sensor size, the micro four-thirds lens would be closer to a 70mm focal length on a full-frame body. This has advantages and disadvantages to it. The problems are that you can’t get lenses that go as wide as those on full-frame cameras. The advantage is that you can get longer telephoto lenses in smaller bodies. This is a process known as equivalencies, which will be very important as we talk about the advantages and disadvantages of each sensor size.
Megapixels. This is your camera’s image resolution, with more not always being better as we talked about off the hop.
Low light capabilities are how your sensor deals with noise in low-light situations, such as inside a building or at dusk. Smaller sensor sizes don’t deal with noise, as well as larger sensor sizes do.
Depth of field is how much or how little of your image will be in focus. Think of this like those creamy backgrounds in portraits vs highly detailed images for landscapes. The larger the sensor, the shallower the depth of field can be. This means you can cause a creamier background with a larger sensor.
Dynamic range is the measure of the range of light intensities from the shadows to the highlights. What this means for your sensor is, a higher dynamic range means it can capture more information in brighter areas and more information in darker areas. Every camera will eventually come across a scene with too wide a dynamic range (think in the middle of a sunny day) to photograph without underexposing or overexposing a section of the image. But some sensors will allow you to see more in the highlights and shadows then others will.
Now that we have some definitions let’s talk about the sensors themselves, starting with the smallest. Remember, we are talking about the size of each of these sensors versus the industry standard, which is full-frame.
Common Sensor Sizes
Four Thirds Sensor
This sensor size is what is seen on the micro four-thirds camera system. Developed in 2008 by Olympus and Panasonic, micro four-thirds is the smallest of the standard interchangeable lens camera systems currently available on the market and is the space most commonly using the four-thirds sensor. Currently, Olympus and Panasonic are the only two camera companies making equipment for the micro four-thirds system, although Panasonic has started to shift its focus towards full-frame cameras. Leaving Olympus as the primary driver behind R&D for this system.
A four-thirds sensor is ¼ the size of a full-frame sensor. This means 4 four-thirds sensors could fit into the space of one full-frame sensor. There are some huge advantages to using the micro four-thirds system versus the other sensors on this list.
Primarily it’s that you can get super high-quality cameras with professional-grade optics in a tiny camera body and lenses. These cameras create amazing photographs that are incredibly detailed in a much smaller package than many full-frame cameras currently on the market. They also tend to be much lighter and smaller than their full-frame equivalents. Typically coming in at about half the weight and size as other lenses and bodies.
Now, this is changing, however. As technology has advanced dramatically since the micro four-thirds system was first announced in 2008, there are some options for ultra-lightweight full-frame cameras with small beautiful lenses. So the advantage of the small compact size is starting to disappear. Although, that advantage is still there somewhat today if you are looking at sharp optics as a primary driver. The price advantage is undoubtedly still there when buying lenses with equally incredible optics. You will typically save a few hundred to a few thousand dollars.
For wildlife and sports photographers, the equivalency factor can be a huge advantage. On a micro four-thirds camera system, you can get a lens that reaches a 600mm focal length in a lens body that is more than half the size and weight of a full-frame equivalent. This is because you need to double the focal length of any micro four-thirds lens to match the focal length of a full-frame lens. So you can get a smaller lens that is easier to carry for far less money.
Now, there are some tradeoffs with getting a sensor this small.
Firstly, the low light performance of these sensors isn’t nearly as good as those bigger than them. If you are shooting lots in low light or shooting lots of subjects moving quickly in low light, micro four-thirds sensors won’t suit your photography. If you can set up and shoot off a tripod with mostly blurred movement or still subjects, then the low light performance won’t affect your photography (being that you won’t need to crank your ISO).
Secondly, light equivalencies. Here we go with the equivalencies again. So, just as we need to double the focal length of lenses, we need to think the same way with aperture. On a micro four-thirds lens, you will need to nearly double the stops of light to reach the full-frame equivalent in terms of f-stops. This means a lens that says it is f/2.8, will operate more like an f/4 lens. A lens that says it is f/4, will function more like an f/5.6 to f/8. So you get less light coming in through the lens to the sensor. This can be a massive downside to these types of lenses.
Equivalencies also play a factor if you shoot lots at very wide focal lengths, as the equivalencies double the length of your lens. So what looks like a 14mm focal length, functions more like a 28mm focal length. Still wide, but not nearly as wide as 14mm.
So, who does micro four-thirds benefit? That question comes down to a few things. What are your priorities in shooting and how much can you spend?
Micro four-thirds cameras still make for incredible travel cameras. They are immensely popular because of their small form factor and long reach. They can fit easily in a travel bag and can help you more easily travel purely in carry on. If you aren’t too worried about shooting in low light situations and aren’t someone who needs to blur out a background severely, this system may be a good choice for you. Especially if you are interested in doing some wildlife photography, but can’t drop $10,000 on a lens; as you can get something that is an equivalent focal length for half to a third that cost.
Typically micro four-thirds will cost far less than their full-frame equivalents.
So that’s the four-thirds sensor and the way it works into taking photos.
APS-C Sensor
APS-C sensors come in two sizes, depending on the company. Nikon, Sony, and Pentax all use APS-C sensors that give about a 1.5x crop factor, whereas Canon uses one that creates a 1.6x crop factor.
You would commonly find APS-C sized sensors in entry-level and enthusiast-level cameras, such as the Canon Rebel or the 10D series. They come with the same limitations on low light performance, depth of field, and aperture equivalences that four-thirds sensors do, although at a lower factor. On these sensors, you will need to magnify the focal length of a lens by 1.5 or 1.6 depending on the brand, rather than doubling it. The same goes for the aperture equivalencies.
One of the advantages of this form factor is that crop factor gives you more distance to play within your photos, which is fantastic for wildlife and sports photographers. Because of this, a few companies made APS-C cameras that were targeted at these shooters, giving them professional level autofocus and speed in a crop sensor body. The other advantage when these sensors were first made was the price. This was because, at the time, creating an APS-C sensor was cheaper than building a full-frame one.
Today, however, this has changed drastically. The cost of producing a full-frame sensor has dropped dramatically, and as such many camera companies are starting to phase out production of APS-C cameras. There is one BIG exception to this, however, and that’s Fujifilm, whose fine line of X series cameras revolves entirely around APS-C sensors. These are some of the most popular cameras today, with people enjoying the retro styling, ergonomics, and quality the cameras produce. But they are one of the few camera companies still focusing on the APS-C sensor style.
So APS-C sensors have many of the advantages and disadvantages of four-thirds, but not as severely limited because the sensor is bigger.
Full Frame Sensor
Full-frame sensors are based on 35mm film equivalents. They are the industry standard for how focal length makes an image look and how a lens functions in practice. They are also the industry standard for how the depth of field is and for being the go-to for most professional photographers today.
Full frame cameras today are being offered in incredibly small packages with amazing specs. Sigma just released the worldès smallest and lightest full-frame camera that rivals the size of a micro four-thirds camera, and about a year ago, Canon unveiled the Canon RP. This tiny and lightweight full-frame camera introduced the full-frame sensor to the interested masses.
These introductions of cost-effective and lightweight full-frame camera options are making full-frame cameras much more appealing for people who do not make their living from photography. There is also an appeal to those beautiful creamy backgrounds and the quality of glass that you can purchase.
So the advantages are pretty clear, you get the most advanced tech and amazing glass as well as most commons primary focus for their R&D.
But there are some pretty clear disadvantages as well. They come in the price factor for many of the top-end lenses and the top end bodies. To put together a standard kit with a good wide-angle, medium telephoto, one prime and a body, you can quickly spend over $10,000. They also come in what you are giving up to purchase a lower-end full-frame camera, as companies need to remove features and put in a lower quality sensor to compensate for the lower price point.
Size and weight also become a factor when you are looking at fast and big glass, as fast and long lenses are hefty and bulky.
Working professionals, those who demand the very best low light performance and those with a need for high dynamic range in each photo, will benefit significantly from using a full-frame sensor. Others may be better looking towards other systems that offer slightly lighter weight and slightly smaller bodies.
Medium Format Sensor
Medium format is the big sibling of all of these lenses. It can come in with double the sensor area of a full-frame sensor (although they can vary a bit in total size). These sensors offer fantastic detail and resolution, and their picture quality is excellent. They are based on the idea of medium format film, although they are not as big as medium format film is. These cameras offer some of the very best resolutions, image detail, and just pure quality.
There are many disadvantages to medium format, however. Today, it primarily comes in shooting speed. Medium format cameras typically only shoot 2 or 3 frames a second, not nearly fast enough to freeze action. And quite slow for recording everyday detail.
They also have traditionally been quite large, and though their size is going down thanks to companies like Hasselblad and Fujifilm creating mirrorless versions, they are still fairly large. The other disadvantage to these systems is the price, as entry-level cameras in medium format currently cost $5,000 and go up from there, and the lenses aren’t accessible either. True high-end medium format can get into the $20,000 and up range.
Medium format is going to be most interesting to those who shoot landscapes, fine art, fashion and commercial work, where they demand the very best in detail and precision and can sculpt a scene to their needs. And where prints will need to be reproduced in a variety of formats, including possibly on the sides of buildings.
To put all of these sensor sizes in comparison, I want to mention one more thing before we sum this up. The iPhone sensor measures at about 1/36th the size of a full-frame sensor. That’s very, very tiny. And as you would expect, it has all the same problems and advantages of smaller sensors. This is one of the reasons that many phones do terribly in low light situations and when you start trying to create large-scale prints with them. This isn’t to say they can’t do a fabulous job, as phone photos have graced newspapers, magazines and billboards around the world. You just have to be very deliberate with your creation. Phones try to keep up through something called computational photography, which is where programs an AI are used to make photos look better or to actively stitch images together to create better photos (like in Night Shot photos on the Google Pixel). This is how the portrait modes work as well.
What Camera Sensor will Suit You?
What do you want to photograph, and what is your budget.
Micro four-thirds systems tend to be some of the most price-conscious and work amazingly well as travel-based cameras.
APS-C today is represented primarily by Fujifilm’s X-series (although Sony does still have some APS-C cameras). The X-series is seen as some of the most fun cameras to shoot with today and are frequently touted as having amazing image quality and lenses. They are a great place to learn photography at a more intuitive level because it brings back a dial-focused system.
Full frame cameras are where most companies are investing their R&D and are where we have seen considerable advancements in the last few years. These cameras offer a great combination of resolution, image quality, light-gathering, and shooting speed. They can be quite big and bulky to carry around, however (depending on the type of lenses you want to shoot with).
Finally, medium format is the goto for detail and resolution. These sensors are commonly seen on the sets of high-end fashion shoots and in the hands of dedicated fine art landscape photographers. They are a bit big and relatively expensive, but while worth it if that is your field.
As I said off the start, a good photographer who understands composition, exposure, light and all that stuff will be able to take fantastic images no matter what camera they are using. Different sensors just offer different capabilities. So put some thought into the type of photography you want to do, your budget, and what is important to you before investing in your next camera system.