Introduction to Camera Sensors.

The Digital Camera Sensor replaced Film as a light-capturing medium.

As much as I love good old-fashioned film and the many great stories recorded on it, I will not be discussing film or videotape in this blog. I highly, highly recommend you research both on your own in order to better appreciate the history of filmmaking, because so many of the standards, processes, techniques, and technologies we will be discussing in the following pages evolved from cameras or projectors that used film or videotape to capture footage, the challenges they had to overcome, and the innovations they led to.

But the reality is that these formats are no longer relevant to someone getting into filmmaking today, and that is the purpose of this book. They’re still very important, they’re still very influential, but they’re no longer viable filmmaking options. 

Let’s talk briefly about Megapixels.

Before we dive into Camera Sensors, I want to have a quick chat about Megapixels. Thanks in large part to the consumer digital camera boom in the early 2000s and the smartphone craze that followed soon after, people have a very poor and skewed understanding of what Megapixels are, what advantages and disadvantages they offer, and what they mean for your image or image quality.

A Megapixel is simply a million pixels, and is used as shorthand to describe the number of Sensor elements in a digital camera or display. A 12 Megapixel camera has around 12,000,000 Sensor elements, or pixels.

Let’s get this out of the way up front: more Megapixels does not necessarily mean a better camera. Additionally: two cameras with the same number of Megapixels are not necessarily equal. 

There are a lot of factors that go into the quality of a camera and the images it’s able to produce, such as: sensor size, lens quality, filter quality, processor, color science, available settings and functions, and yes, the number (and size and quality) of Megapixels. So the number of Megapixels is a factor, but it’s only one of many factors.

For instance, let’s say we have two Sensors that are the exact same size, but one has 36 Megapixels and the other has 12 Megapixels. Because the Megapixels on each of these Sensors must fit into the same space, the camera with 12 Megapixels is going to perform much better in low light situations because the individual pixels are larger, and each one can collect more light information. However, if you are taking a photo that needs to be blown up into a very large print, the camera with 36 Megapixels will likely be a better choice, as there is more fine detail information stored in those additional pixels. Neither is inherently good or bad, just different. It all depends on what you need from your gear.

Additionally, just because your smartphone camera has the same number of Megapixels as a professional camera, that doesn’t mean it will perform as well or produce the same quality of images. Those pixels in your smartphone camera are crammed onto a Sensor that is about the size of a grain of rice, which offers little surface area for light to land on. The Sensor on the professional camera is about twice the size of a postage stamp, so its pixels are much larger and therefore able to collect more light. And the more light you’re able to collect, the better your images will be–because light information = images.

The basics: What is a Sensor?

Think of the Sensor as the engine of your camera. It will determine what size images you’re able to produce, the resolution, the low light performance, the frame rate capabilities, the size of your camera, the amount of power your camera requires, and much, much more. There are many things that contribute to the kinds of images you’re able to achieve with your camera, but it begins and ends with the Sensor.

Digital sensors are complicated pieces of technology, and there is a lot of science behind them that I am not going to cover in great detail here. This is partially because you don’t need to understand the science in order to understand how your sensor performs, and partially because I only have a vague grasp on the science myself (quantum physics, and photons, and charged electrons, and depletion layers, and P-N Junction Diodes–it all kind of makes my head hurt).

But I absolutely encourage you to seek out this information once you get a handle on the basics, because not only is it interesting, it will give you a better understanding of what your camera is actually doing when you press Record. It will also help ease the pain of spending your hard-earned money on a new camera when you realize just how extraordinary the technology inside really is.

That said, we will be discussing a bit of the science in order to prepare you for some of the Sensor-specific problems you may encounter, and hopefully help you understand why they happen and how to mitigate them.

Note: Don’t expect to understand everything right away. This technology took decades to develop and refine, and I’m only going to give you a simplified overview of how things work so you can begin Practicing Productively. Everything covered in this blog will make more sense when you start practicing with cameras and experimenting with different settings hands-on. 

Understanding these things takes time, and just like you don’t need to be a computer programmer to know how to use an app on your smartphone, you don’t need to be an imaging scientist to know how to get the most out of your camera’s Sensor. I’ve been working with cameras for over ten years, and I’m just now feeling like I can wrap my head around it. But the goal of this blog is to give you a headstart, an extra leg up in your learning, so we’re going to dig a little deeper than you might otherwise.

So, what is a Camera Sensor?

A Camera Sensor is a Solid State Device, or SSD, that captures light and converts it into electricity, which your camera’s computer measures and turns into a digital image. The sensor is the digital equivalent of a frame of film.

There are two main types of Sensors: CCD and CMOS. Understanding each and their unique benefits and drawbacks will help you make more informed decisions as to what cameras you should buy, as well as make it easier for you to pick up a camera and have a basic understanding of how it delivers images.  

CCD: Charged Coupled Device.

The CCD was developed in 1969, and was the first effective digital Sensor. The CCD solved many of the problems with early digital imaging processes by doing away with the wired grids containing several photoelectric diodes, and replacing them with a single piece of silicon and one big photoelectric diode

Here’s an overview of how a CCD works:

1. Your camera shutter opens, letting in light to expose the image

2. Light hits the CCD, and electrons in the silicon react to the light

3. The shutter closes

4. The CCD holds the charge of those electrons in place on a pixel grid (made up of insulated channel stops and strips of charged aluminum)

5. The CCD then shifts the electrons from the pixels of that exposure, row by row, off the sensor to be read and processed

6. The processor measures the charge of each pixel and converts it to Binary, which becomes a digital image

7. The shutter cannot open again to expose a new frame until that information is cleared

Don’t worry if that didn’t make much sense, the important thing to know is that this process has a few specific benefits and drawbacks for you as a filmmaker:

CCD Benefits

• Simpler design with fewer wires, pieces, and parts

• Clean images with little digital image noise (or grain)

• Greater light sensitivity

• Good Dynamic Range (the range between the brightest light and darkest shadow)

CCD Drawbacks

• Slight loss of voltage each time a row of electrons is shifted off the sensor, leading to some quality loss not suitable for higher resolution video

• Shutter must remain closed until all information is unloaded from the sensor to the memory, a relatively slow process that limits frame rate and burst rate capabilities

• Requires lots of power and drains batteries more quickly

The CCD reigned supreme in digital video cameras for a couple of decades. But there was another type of digital Sensor being developed around the same time as the CCD, one that wouldn’t become widely available until much later, when manufacturing processes finally caught up to technological requirements.

CMOS: Complementary Metal-Oxide-Semiconductor

If you’ve shopped for cameras in the past few years, you probably recognize the term CMOS Sensor. CMOS Sensors started showing up in commercially available cameras in the 1990s. Like the CCD, CMOS Sensors are comprised of a single piece of silicon with one big photoelectric diode. But instead of capturing light information in one single exposure, CMOS Sensors expose an image sequentially, line-by-line, from top to bottom.

Here’s how the CMOS Sensor works:

1. Each pixel on a CMOS Sensor grid is equipped with a Capacitor (battery) and Signal Amplifier (voltage booster), and hooked up to a tiny wire that leads to the processor

2. When exposed to light, the amplified voltage of each pixel travels down the wire to be processed and stored

3. This happens line-by-line, beginning with the first line of pixels at the top of the Sensor, and working its way down to the last line of pixels at the bottom of the Sensor, much like the scan lines on TVs and computer monitors

4. Whereas a CCD Sensor exposes the entire image at the same time, a CMOS Sensor exposes the image a line at a time, meaning it captures the top of the image a fraction of a second before it captures the middle of the image, which is captured a fraction of a second before it captures the bottom of the image

Again, all you need to know is that this process means the following for you as a filmmaker::

CMOS Benefits

• Works more efficiently and requires less power, as it doesn’t have to hold charges and shift electrons with each exposure

• Able to capture images faster since image data is being processed even during exposure, leading to increased frame rate and burst rate capabilities

• More built-in functionality

CMOS Drawbacks

• More digital image noise due to fluctuations in individual pixel amplifiers

• Decreased light sensitivity caused by each pixel having a transistor next to it; some of the light photons end up hitting the transistors instead of the photoelectric diode

• Capturing and sending pixels to the processor line-by-line causes Rolling Shutter

Rolling Shutter is a problem you will encounter sooner or later with a CMOS Sensor. It may be a small problem or a big problem, depending on the camera you’re using and what you’re using it for.

Because CMOS Sensors capture images line-by-line, the top is captured before the middle, which is captured before the bottom. This isn’t usually a problem if you have the camera locked down on a tripod, but what happens when you start to move the camera? This causes Rolling Shutter, or the Jello Effect as it’s sometimes called. As you move the camera from side to side, the camera is in a different place when the last line of the image is captured than it was when the first line was captured. This leads to footage that looks unnaturally wobbly or bendy.

Editing software can help with Rolling Shutter, but it can’t completely fix it. Faster camera processors can also reduce the problem by reading the Sensor data fast enough to compensate for some movement, but the problem will still exist. If your camera is especially prone to Rolling Shutter, you will need to plan your shoots accordingly, doing what you can to minimize or slow down camera movement as much as possible. If your work requires a lot of camera movement, such as sports or some wildlife videography, you will want to research which cameras have little to no Rolling Shutter, and a CCD or smaller Sensor may be your best option.

Sensor Sizes

Digital sensors come in a variety of sizes and even shapes, from extra large Medium Format Sensors to very small smartphone camera Sensors. But there are four main sizes you’ll likely be dealing with as you’re purchasing and using cameras for video:

• Full Frame (35mm equivalent)

• APS-C (Crop Sensor)

• Four Thirds (or Micro 4/3)

• 1-inch

Full Frame: 36×24 mm

The Full Frame Sensor is the largest Sensor option for most professional video gear. It is the standard against which all other Sensor sizes are measured, particularly when it comes to lenses.

The Full Frame Sensor is roughly the size of a traditional 35mm frame of film. Though not the most common Sensor size, due to cameras with smaller sensors generally being more compact and affordable, many professional videographers choose cameras with Full Frame Sensors for their work.

Because the Full Frame Sensor is the largest used for video, it has the potential for capturing the most light. (I say potential because there are many other factors that determine how much light will reach your sensor; lens, aperture, filters, etc.) Thanks to their ability to capture more light, Full Frame Sensors tend to perform better than smaller sensors in low light situations. Circling back to our conversation about Megapixels, the Megapixels on Full Frame sensors are also able to be larger than those on smaller Sensors, simply because there is more space to fill. And the larger the pixels, the more opportunity for light to find them (light information = images).

Full Frame Sensors also allow for better Dynamic Range, more shallow Depth of Field, and wider Fields of View than smaller sensors; all of which we will discuss in more detail in a later post, and all of which are benefits of being able to collect more light.

Full Frame Sensor Benefits

• Work better than smaller sensors in low light situations

• Larger pixels mean better signal to noise ratio and cleaner images

• Can achieve more shallow Depth of Field

• Better Dynamic Range due to larger pixels with less noise

• No change in Effective Focal Range for lenses (see APS-C section below)

Full Frame Sensor Neutral

• Require larger camera bodies in order to house the Sensor and processors 

• Can capture widest Fields of View

Full Frame Sensor Drawbacks

• More expensive to make (and therefore buy): sometimes as much as twenty times more expensive to manufacture than the next Sensor size down

• Require bigger, heavier, and more expensive lenses

• Issues like Rolling Shutter can be exaggerated due to increased Sensor size

• More limited selection of lenses, as only Full Frame lenses will work properly with Full Frame Sensors

APS-C (Crop Sensor): 23.6×15.7 (Sony, Nikon, Fuji), 22.2×14.8 (Canon)

Before we continue, you’ll notice that this Sensor size varies slightly between brands; more specifically between Canon and every other brand. It’s not a big difference, but it is a difference. As we discuss Crop Factor below, keep in mind that most APS-C Sensors have a 1.5x Crop, while Canon’s APS-C Sensors have a 1.6x Crop.

A 1.5x Crop means that you would have to zoom in 1.5 times on a Full Frame Sensor to match the size of an APS-C Sensor.

This is an important thing to remember, especially as you’re choosing lenses for your APS-C camera.

We will talk about lenses in greater detail in a later post, but know that the Field of View, or area a lens will exhibit, is determined by the lens’s Focal Length. The Focal Length is listed in millimeters (30mm), or a range of millimeters if the lens is capable of zooming (24mm-50mm).

Anytime you’re using a camera with a Sensor that is smaller than Full Frame, you must apply its Crop Factor to the Focal Length of whatever lens you’re using, in order to account for the smaller Sensor size.

For example: if you buy a 30mm lens for your APS-C camera, the Crop Factor is 1.5. You must apply this Crop Factor to your lens (30 * 1.5 = 45) to find the Effective Focal Length, or 45mm. Therefore, on your APS-C camera, your 30mm lens will have the Effective Field of View of a 45mm lens on a Full Frame camera.

But why does this matter? It matters because you will learn to use different Focal Lengths and Fields of View to achieve different effects for telling stories. Certain Focal Lengths simulate human vision, while others can offer unique and unnatural perspectives that you as a filmmaker can take advantage of or make sure to avoid, like the popular Fisheye or Peephole effect of very wide lenses. So if you’re using an APS-C camera, and you want to use a 24mm Field of View for an establishing shot to open your scene, you’ll need to use a 16mm lens.

So an APS-C Sensor is smaller than a Full Frame Sensor, that means it’s not as good, right? Not necessarily. It’s true that it isn’t able to capture as much light and that it will generally have smaller pixels, but Crop Sensors have their advantages, too. For instance, if your work requires you to frequently zoom in on far away subjects, Crop Sensors will give you added reach with every lens. Remember, a 200mm lens (a telephoto, or very zoomed in lens) will effectively be a 300mm lens (an even more zoomed in lens) on an APS-C camera. This added reach can come in handy if you’re filming airplanes at an air show, horses on the opposite side of a racetrack, or wildlife far off in the distance.

Because APS-C Sensors are smaller, this also allows for the camera bodies themselves to be smaller and lighter. More compact cameras are easier to pack and carry on long trips, can fit into spaces that larger cameras can’t, and can often be used with more lightweight and affordable tripods and gimbals.

APS-C Sensors are much cheaper to manufacture, as are the smaller camera bodies they’re housed in. Therefore APS-C cameras and lenses tend to be more affordable, and this is a big part of why they’re the most popular size of Sensor overall.

APS-C Sensor Benefits

• Still a fairly large Sensor, despite being smaller than Full Frame

• Cheaper to manufacture, more affordable

• Larger selection of lenses, as they can use both APS-C and Full Frame lenses (with a crop)

• Telephoto lenses can be smaller and more compact due to Crop Factor

• Relatively good Dynamic Range and Depth of Field

APS-C Sensor Neutral

• Can be housed in more compact camera bodies

• Crop Sensor increases Effective Focal Length

APS-C Sensor Drawbacks

• Not as good in low light

• Not suitable for super wide angles 

Four Thirds (Micro 4/3): 17.3×13 mm

The Four Thirds Sensor has seen an uptick in popularity among filmmakers in recent years, thanks in large part to Panasonic releasing a number of affordable, high-quality, videocentric Micro Four Thirds cameras.

Four Thirds Sensors are about 30-40% smaller than APS-C Sensors. Whereas the APS-C sensor has a 1.5x Crop Factor, the Four Thirds Sensor has about a 2x Crop Factor. A 50mm Full Frame lens on a Four Thirds camera would have a 100mm Effective Focal Length. For this reason, Four Thirds cameras have an even greater advantage when filming far off subjects, thanks to the added reach from the 2x Crop. A 300mm lens effectively becomes a 600mm lens, but in a much smaller package than most 600mm lenses.

Four Thirds Sensors use a different Aspect Ratio than the other Sensors on our list.

A square is as wide as it is tall, so its Aspect Ratio is 1:1. The Aspect Ratio of most modern TVs is 16:9. The Aspect Ratio of Full Frame and APS-C sensors is 3:2. The Aspect Ratio of Four Thirds Sensors is–drumroll please–4:3. However, just because the Aspect Ratio of the Sensor is different, this doesn’t mean it isn’t capable of filming in 3:2 or a variety of other Aspect Ratios. Most modern Four Thirds Sensors have options for filming with similar settings to other Sensors.

The further we move away from Full Frame, the smaller our pixels must be, and the more our low light performance, Depth of Field, and Dynamic Range begin to suffer. Less light is being collected, and therefore we have less information to work with. And while Sensor technology is constantly improving, these improvements benefit the larger Sensors just as much as the smaller ones, so the gap in performance remains much the same even as overall performance improves.

Four Thirds Sensor Benefits

• Cheaper to manufacture, more affordable

• Telephoto lenses can be smaller and more compact due to increased Crop Factor

Four Thirds Sensor Neutral

• Can be housed in more compact camera bodies

• Smaller Sensor further increases Effective Focal Length

APS-C Sensor Drawbacks

• Not as good in low light

• Greater likelihood for digital image noise

• Fewer native lens options

• Decreased Depth of Field and Dynamic Range

• Not suitable for super wide angles 

1-inch

The further hough not the smallest Sensor available in professional video cameras, it is increasingly becoming the smallest most professionals are willing to work with. As Sensor technology advances and manufacturing becomes cheaper, most camera companies are relegating Sensors smaller than 1-inch to consumer cameras only.

While the Crop Factor for APS-C is 1.5, and for Four Thirds is 2x, the Crop Factor for 1-inch Sensors is a whopping 2.7x. However, there are very few Interchangeable Lens Cameras that use a 1-inch Sensor, so you will likely be applying the Crop Factor to a Fixed Lens, or one that is built into the camera.

This isn’t necessarily a bad thing. Many modern 1-inch Sensor cameras are able to achieve HD and even 4K resolutions, and for those looking to get into filmmaking on a budget, being able to buy a camera and lens combo for less than the price of an entry level APS-C camera body alone isn’t a bad option.

That said, all of the drawbacks we talked about with APS-C and Four Thirds Sensors become even more pronounced with 1-inch Sensors. Low light capabilities are poor, Depth of Field is limited, and Dynamic Range is greatly reduced.

However, there is one area in which 1-inch Sensors are increasingly finding a niche: drones. Because drones need to be small and light, they use very small cameras with very small sensors. For most drones on the market, a 1-inch Sensor is actually quite a big step up, and newer drones are starting to include cameras with 1-inch Sensors to push drone photo and video capabilities to the next level. 1-inch Sensors are also a good fit for drones because things like low light performance and shallow Depth of Field aren’t as important, and the added reach of the smaller Sensor often proves advantageous from the air.

Overall, 1-inch Sensors offer an affordable way to get into professional filmmaking, but require a good understanding of their limitations and how to compensate for them. 

1-inch Sensor Benefits

• More affordable

• Good for drones

1-inch Sensor Neutral

• Can be housed in more compact camera bodies

• Smaller Sensor increases Effective Focal Length

• Usually comes with a fixed lens

1-inch Sensor Drawbacks

• Not good in low light

• Greatest likelihood for digital image noise

• Virtually no lens options beyond what comes on your camera

• Greatly reduced Depth of Field and Dynamic Range capabilities

What camera should you buy?

Well…it’s complicated.

This is the most common question I’m asked, and it is also among the most impossible to answer–though for reasons you may not expect. That said, there are some ways you can go about determining what kind of camera gear you need. 

First things first: You need more than a camera.

When people think of video production, they tend to think of someone working a camera. Certainly this is one (important) aspect of it, but when was the last time you watched a video that didn’t have any sound? Or that was so dark you could barely see the person speaking? Or where the camera was shaking and moving around so much that you couldn’t watch more than a few seconds without getting vertigo?

If you plan on learning and working in video production, you will need three main pieces of gear, and ideally four:

(*This list assumes you already have a computer to edit on. If not, add a computer to the very top of the list, because the best footage in the world is useless if you can’t edit it.)

Necessary

1. Camera (including lens)

2. Microphone

3. Tripod

Optional but recommended

4. Light (with light stand) 

There are exceptions to this list, and there are dozens of other important pieces of gear that you’ll eventually want for your filmmaking endeavors. But these are the essential items you will need to begin learning the craft and producing complete, watchable videos. I started my professional video career with just those first three things.

Start thinking about it this way: if you have $1,000 to spend on a camera but you don’t have any of those other pieces of equipment, you shouldn’t be shopping for $1,000 cameras. If you are just starting out, are working with limited funds, and don’t have any video gear whatsoever, here is a guideline for how you should budget for gear:

• 50-60% on a camera and lens

• 20-30% on a quality microphone

• 10-15% on a tripod (a good tripod can last you forever, so do your research and invest in something that will allow you to grow)

• 5-10% on a light*

If you have a larger budget, I would add lenses (plural) and secondary cameras to the camera budget, I would add audio recorders and boom stands and secondary mics to the microphone budget, sliders and gimbals to the tripod budget, and multiple lights to the lighting. But generally, the breakdown holds. Investing in a wide assortment of gear gives you flexibility and, crucially, redundancy.

*You can get by without a light if you know what you’re doing and are willing to put a little more time and care into planning your setups to use natural light from windows or reflecting room lighting using things like poster board. But with the advent of LED lighting technology, video lights are becoming more affordable and easy to use by the day. Even a $50 LED panel can make your life much easier and your work noticeably more professional. 

Next consideration: What are your needs and goals?

What kinds of videos do you plan on making? The type of camera and supplementary equipment you need will depend largely on what kind of work you want to do.

If you want to produce narrative films, you might want something that records in higher bitrates for color correction, can be built out into a filming rig with follow focus controls, shoulder mounts, and matte boxes, and can work with a wide variety of lenses. You will likely want a larger, sturdier tripod that won’t be easily knocked over on set, and either a shotgun microphone and boom arm or a lavalier microphone for miking your talent. 

If you want to produce documentary films, you might be better off going with something lightweight and compact that can be carried easily, set up and torn down quickly, and will allow you to work in a variety of different spaces, like cars and doctor offices. A portable but sturdy tripod would probably serve you best, while shotgun mic and boom pole will give you flexibility for shooting static interviews as well as run-and-gun audio. 

Maybe you aspire to make travel and adventure films, in which case you’ll want something rugged, durable, and weather-sealed for when you’re hiking up the side of a mountain or kayaking to get your next shot. Having a lightweight tripod will be essential for carrying on long hikes–but don’t skimp. Taking a timelapse from a windy mountain overlook requires rock solid stabilization. An on-camera shotgun mic or a lavalier that plugs into your phone and can be stored away in a waterproof bag when not in use may suit your needs.

Or perhaps you’re wanting to start your own vlog, and you need something portable and lightweight to keep up with your fast-paced life and filming style. 

Always start by figuring out what your production needs are, what you want to produce, and what you hope to accomplish. This will steer you toward or away from this camera or that one. Some things to consider:

• What will you be filming? (interviews, narrative films, vlogs, presentations, products, commercials, etc.)

• Where will you be filming? (a studio, your house, client sites like offices and manufacturing facilities, outdoors, indoors, controlled environments, unknown environments, etc.)

• How will you be filming? (will you plan out and storyboard each shot, will you be filming events you can’t plan for, will you be doing most of your work on a tripod or handheld, will you be by yourself or working with a team, etc.)

• Why will you be filming? (do you plan on being hired by others or producing your own projects)

• Where and how will your work be delivered? (TV, DVDs, presentations, internet, intranet, etc.)

As you begin going through this list, you will start to get a sense of what you need from your gear. Allow these criteria to guide you–even if they take you in the opposite direction of whatever camera or microphone you’ve had your heart set on.

I’ve never known another filmmaker whose needs were the same as mine, and I’ve never met another filmmaker who used the same gear I do. We choose our equipment to suit our needs, and it is important that you begin thinking in these terms. We live in an incredible time where we have many different camera companies producing many excellent camera options. What’s right for me may be completely wrong for you–and that’s okay.  

Finally, leave yourself room to grow.

You may be a novice today, but hopefully you will stick with it, and six months or a year from now you’ll be much more advanced and ready to tackle bigger filmmaking challenges. But video gear isn’t cheap, and it’s not always easy to constantly upgrade your equipment every few months. So as you determine what you need to get started, think about where you want to be a year from now and make sure you’re investing in something that will not only get you started, but also allow you to grow in your work.