Every camera has a sensor, and one of the biggest differentiators between cameras is the physical size of the sensor. Which size is best? Are there any sizes you need to avoid?

If you’re a beginner to photography and cinematography you’ll be hard-pressed to wrap your head around all the marketing BS and technical jargon. Here’s a quick video of the simplest explanation I can think of:

Exclusive Bonus: Download my free cheatsheet (with examples) of the most used focal lengths in film (PDF file optimized for mobiles and tablets).

The sensor size

A sensor size is always written as the:

Length of the sensor (in mm) x Breadth of the sensor (in mm).

The reason it’s in millimeters is because the sensors are small, and the number in millimeters is easier to remember. Nothing fancy.

Is there a standard sensor size?

There isn’t one. The only standard from film that has survived the digital revolution is the Full frame or 135 format (from photography). The size of this sensor is:

36mm x 24mm

The most expensive DSLRs and mirrorless cameras from Canon, Nikon, Sony, Leica and Pentax have sensors in this size. 35mm film (for photography) was (and is) the same size.

This is why I use this size to calculate my crop factors and the 35mm equivalent.

What about cinema?

Cinema has its own standards, but most of them have changed numerous times over the years and are hard to track down and understand. The only surviving ‘standard’ (in quotes because it’s open to interpretation nowadays) is:

Super 35mm. The length is 24.89mm.

What about the breadth?

It can vary depending on the aspect ratio (click to learn more). Cinema has two ‘popular’ aspect ratios: 1.85:1 and 2.39:1 (Widescreen). Depending on this the height can change.

Which cameras are which?

This is where camera manufacturers propagate FUD to keep you interested. Here’s a table of some cameras and their horizontal sensor sizes:

Camera Horizontal sensor size in mm
IMAX 69.6
Arri Alexa 65 54.12
65mm film (TOD-AO) 52.6
Sony a7S II and a7R II 36
Canon 5D Mark III, 5Ds and 1DX Mark II 36
Nikon D810 and D5 36
Red Epic Dragon 30.7
Red Epic 27.7
Sony FS7 25.5
Blackmagic URSA 4.6K 25.34
Super35mm Film (3-perf/4-perf) 24.89
Sony F55 24
Arri Alexa SXT/Mini 23.76
Nikon APS-C (Typical) 23.6
Red Raven 23.04
Canon APS-C (Typical) 22.2
35mm Academy Film 21.95
Panasonic GH4 and other MFT sensors 17.3
1″ Sensors/Nokia 808 PureView 13.2
2/3″ CCD HDTV broadcast cameras 9.59
1/3″ CCD HDTV and iPhone 6s 4.8

I’m overwhelmed! Which is the best?

I know, if you’re a newcomer you’ll have no clue. It’s my word against the rest at this point. If you really want to know the truth you’ll have to get your hands dirty and get technical.

Here’s my simple suggestion. You can differentiate sensor sizes using this matrix (this is overly simplified, so please realize it’s only for newcomers who don’t want to learn the technology):

At the same resolution Better the Worse the What’s different?
Larger the sensor Light collecting ability (low light ability), shallow depth of field Price, lens size Due to changes in sensor size, lens size and other phenomena, you won’t get the exact same image in practice. Each sensor-lens combination has a unique look.
Smaller the sensor Depth of field, smaller lenses low light performance

In theory (pure geometry) you should be able to recreate the exact same look with large or small sensors given perfect conditions. But it’s never the case. In the real world, you can never match two sensors 100%, and that means:

Each sensor-size and lens combination has its own look. It’s not ‘better’ or ‘worse’, but different. Aesthetically different.

In short, pick a sensor like you would pick a paint brush…or a toothbrush.

Hey then! Why do people keep praising large sensor cameras?

Larger sensors are more expensive to produce, that’s why the cameras are expensive. Have you ever heard of the saying:

You get what you pay for?

Well, camera manufacturers know how to milk that to create uncertainty.

Let’s say you go to the market to buy mangoes. There are two boxes, one with small mangoes and next to it another box with bigger mangoes. Do bigger mangoes always taste better than the smaller mangoes?

You and I know that’s not the case. Small mangoes can taste great too. But the uncertainty here is (especially for newcomers) – does the size have anything to do with it?

You can add various elements to make it even more confusing – change the quality of the box, mangoes are of a different color, one bunch of mangoes have a hologram sticker, the bigger size is from an exotic country, and so on. Soon, you won’t know why the higher-priced mangoes are higher-priced. Because of the popularity of mangoes, we know the most important criterion is taste. But replace mangoes with some other unknown fruit or vegetable or camera-sensor you’ve never heard of before. Now you see, don’t you?

Now, when you compare the specifications of large-sensor DSLRs to small-sensor DSLRs from the same manufacturer, you’ll see the manufacturer cleverly neglects to add features found in the more expensive camera to the smaller-sensor camera.

You have to ask yourself: Why don’t they keep the features the same? If the sensor-size was so obviously important, surely they don’t have to omit their cutting edge technology features like weather protection, faster autofocus, better viewfinder, and so on. They want you to associate image quality with sensor size, when it isn’t. They hope you won’t notice.

Therefore, when you buy big-sensor cameras, you’re not only paying extra for the bigger sensor, but also for additional features in the camera.

Which sensor should I buy?

Here’s the best answer to that question: Don’t bother about the sensor!

See what others have done with the cameras you’re interested in, and then ask yourself:

Can I afford to lose this camera tomorrow (and the money I paid for it?)

If yes, then buy it, and learn to shoot great photographs or videos with it. If you’ve been following news you’ll know people shoot movies even with GoPros and iPhones these days, so stop chasing large sensor cameras with your wallet. It’s not going to make you a better photographer or cinematographer. It’s not going to make your film any better, and it’s not going to make you famous.

Wearing the best running sneakers in the world isn’t going to win you an Olympic medal, nor is it going to make you the fastest human. The same applies to cameras:

Point your expensive camera at crap if you want to, but it won’t make crap look expensive.

An expensive camera will surely empty your wallet, but won’t guarantee production values. Then isn’t it better to spend your money on what will guarantee production values? Things like better actors or models, better sets and wardrobe, traveling, extra hands, and so on?

I hope this simple explanation of sensor sizes has helped you understand it on a gut-level. That was all I intended to accomplish. If you feel it has helped, please let me know!

Exclusive Bonus: Download my free cheatsheet (with examples) of the most used focal lengths in film (PDF file optimized for mobiles and tablets).