Camera sensors, which one to choose? In the 21st century, the camera market is both more exciting and more confusing than ever. With choices ranging from tiny mirrorless cameras to huge full frame DSLRs and with different sensor sizes in the mix to make things even more complicated you have as many options as you could ever want.
If you don’t fully understand the effect that these different options have on the photos or videos you take, don’t worry.
You’re not alone.
I’ve written this article for you as a guide to understanding the differences and the effects of sensor sizes in modern cameras. I hope that his can help you make an informed decision about what camera to buy.
Why Are There Different Sensor Sizes?
Camera technology is driven by two principal competing desires. On one hand, the image the camera produces should be as clean, sharp, and beautiful as possible. On the other hand, the camera itself should, for most consumers, be reasonably small and affordable.
In the past, the prior impulse motivated larger sizes for the sensors inside of cameras, which traditionally gave the best image quality possible. However, as camera technology has developed over the years, it has become increasingly feasible to satisfy the second impulse of size and affordability by decreasing the size of the sensors.
Consequently, the camera market now encompasses a large range of sensor sizes, from full-frame cameras to the tiny sensors found in phone cameras. But smaller sensors may no longer mean the hit to image quality that you might think. In fact, understanding the properties of different sensor sizes reveals the viability of smaller sensor sizes in today’s market.
Understanding Crop Factor
The idea of crop factor is based around the relation of any sensor size to a 35mm wide film, which was once the standard for professional cameras. A modern full frame camera sensor covers the same overall area as 35mm film, meaning that it has no crop factor. A smaller sensor, however, is often referred to as a crop sensor due to its relation to the size of 35mm film.
Since 35mm is 1.6x bigger than an APS-C sensor, it’s said that APS-C sensors have a 1.6x crop factor.
A micro four thirds sensor, twice as small as 35mm film, has a 2x crop factor.
Field of View, Focal Length and Sensors’ Main Differences
Ultimately, the principal effect of your sensor’s crop factor will be how it affects your camera’s field of view and the focal length of the lenses you use. When taking pictures, the focal length of a lens is critically important in determining the image that’s going to come out of your camera.
For example, a 100mm lens will make the subject of your image appear twice as big as a 50mm on your camera sensor and your resulting picture. This is the fundamental idea behind zoom lenses, which shift from shorter to longer focal lengths as you turn them, and consequentially make the subject of the image appear bigger. Focal lengths do not only affect the size of your subject, however, but also the fundamental appearance. Shorter focal lengths found in wide angle lenses with a large field of view cause a type of distortion in the final image that is usually pleasing for landscape photos but unflattering for portraits. Longer focal lengths found in lenses with smaller field of views aren’t particularly useful for landscape photos but are usually very flattering for portraits.
If you are not yet familiar with the concept of focal length I’ve written an extensive article that explains the role it plays in photography. You can find it here The Ultimate Beginner Guide to Landscape Photography. And feel free to ask questions in the comments section below.
When choosing lenses and considering focal length, your sensor size is as important as the lens itself. With a full frame sensor, there’s no need to account for the crop factor’s effect on the lens and a lens indicated as 50mm will appear exactly as a 50mm lens traditionally would. Accounting for crop factors, however, is quite easy once you know how. The focal length of the lens simply needs to be multiplied by the crop factor.
A 50mm lens on a micro four thirds camera multiplied by the 2x crop factor would be the equivalent of a 100mm lens on a full frame. To achieve the effect of a 50mm lens on a micro four thirds sensor, then, you would use a 25mm lens. With an abundance of lenses in essentially all focal lengths available for modern cameras, the effect of crop factor on focal length is not a particularly limiting factor in camera usage.
Smaller sensors can even be useful in doubling the magnification and field of view of much more expensive lenses. A micro four thirds zoom lens that goes to 300mm can be used like a 600mm lens would be on a full frame camera without the often-exponential accompanying increases in size and cost.
To find a good example you can read my review of the Olympus M. Zuiko 40-150mm f/2.8 which being a lens for micro four thirds sensors produces an image equivalent of a 80-300mm full frame.
Advantages and Disadvantages (of Each Sensor Size)
Outside of allowing you to use lenses as their stated focal lengths, full frame sensors are often praised for their performance in low light and minimization of noise. This is probably the biggest factor to keep in mind when considering a full frame sensor and the importance of low light performance. They can also produce beautiful bokeh, where the background of an image blurs out into aesthetically pleasing round spots of light.
On the other hand, full frame cameras still can’t overcome their biggest downsides. Full frame DSLRs are big, bulky and can be quite expensive. If you choose a full frame mirrorless they will yes be lighter than DSLRs, but you need to take into account that they will mount the same lenses. So weight (and prize) still play a role here.
An APS-C sensor is ultimately the middle ground between a full frame and micro four thirds sensor. It offers great dynamic range and good low light advantages of full frame without quite the same bulk and at a much lower price. If I had to buy an APS-C sensor camera today I wouldn’t think twice about it and go straight to the Sony a6500 mirrorless. It’s small, it allows shooting 4k videos and it has a really fast autofocus system. You can find it here (Amazon link). On a smaller budget is the versatile Sony a6000 you’ll hardly find a more versatile camera body for that price on Amazon.
Micro four thirds sensor cameras instead have the main advantage of being small and portable. Mirrorless micro four thirds cameras can be much smaller and lighter than full frame or even APS-C cameras, an advantage that often extends to the lenses as well.
Many lenses intended for modern full frame or APS-C cameras can be used on mirrorless cameras with micro four thirds sensors with affordable and effective lens mount adapters.
Conclusion: Is a Bigger Sensor Better?
Once upon a time, the answer to the question of size in a camera sensor might have been to go as big as you could potentially afford. But in the modern market, the advantages offered by smaller sensors such as APS-C and Micro Four Thirds means that in a lot of cases they are the best way to go. I am not at all against full frame cameras, but price and weight are major factors you should take into consideration.
Moreover advancements in digital processing of modern cameras mean that a camera with a small sensor from a leading company will usually have processing technology that completely alleviates loss of image quality in low light, so even the low light advantage of full frame sensors has diminished.
If you can spend less on the camera body and put that money towards the wide variety of lenses available to the APS-C or Micro Four Thirds user, you can achieve image quality that rivals any full frame camera without limiting your lens options or breaking the bank. Moreover, you’re much more likely to be able to take your camera wherever you go without bulking up a bag, placing a whole world to photograph more easily at your fingertips.
Of course, every sensor size has its place, and none of them will be going away anytime soon! I hope that this article has helped you clearing up a bit of confusion on camera sensor sizes and as always don’t hesitate to ask me questions in the comments section below. I’ll be happy to reply.
Stefano Caioni is the founder of Pixinfocus. His passion for photography helps him discover new places and live new adventures.