Selecting a Camera for FPV

by | May 24, 2015 | design, FPV | 1 comment

Many parts go into an FPV system:  a video transmitter, a video receiver, a viewing device, an optional on-screen display device, two different power sources, two different electrical systems, and, of course, a camera.  Of all the parts on this list, the most important is probably the camera. The camera you choose basically determines the maximum performance of the system. Sure, you also need a decent quality transmitter and a good viewing device, but the even the very best video transmitters and view screens cannot improve the video signal coming from the camera. The point is, choosing a camera for your FPV system is one of the most important decisions you will make as far as performance is concerned.

That said, FPV cameras are one of those components with an extremely large variation in price. The cheapest FPV cameras run about $15, and the most expensive can cost $500 or more. So you will probably want to keep your budget in mind when choosing an FPV camera, in addition to thinking about quality.

Choosing an FPV Camera

There are a number of different choices you need to make in the process of narrowing down your choice of FPV cameras to one:

As with all other multirotor components, your choice will depend on the design of your aircraft, your personal preferences, and the type of flying you do. It will also be heavily influenced by your budget. Again, the price of different FPV cameras varies widely and you will need to make sacrifices in certain areas to keep the cost of your FPV system in check; but that is fine because unless you are a professional multirotor cinematographer, you don’t actually need a top-of-the -line camera.

Image Sensor Type:  CCD or CMOS

The first decision to make when choosing your FPV camera is the image sensor type. It is not really a decision though because, spoiler alert, CCD technology is much better than CMOS for FPV. I think it is useful to understand why though because it is useful to have a good understanding of the capabilities and limitations of your FPV system.

Camera image sensors are the parts of cameras that take in light and translate it to electronic data, which is in turn translated back to light by some kind of display screen. There are two different types of image sensors found in the vast majority of cameras:  CCD and CMOS. Each of these technologies has its own set of advantages and disadvantages, but we will see that CCD technology is better for FPV work:

CMOS Sensors
  • cheaper
  • a little bit smaller
  • a little bit lighter
  • use less power
CCD Sensors
  • less “jello effect”
  • better performance in extreme lighting conditions
  • greater dynamic range
  • less noise
Advantages of CCD Sensors

CCD sensors have a couple important advantages over CMOS sensors that make them better suited for use in an FPV system. First, because of the way CCD cameras capture images, versus the way CMOS cameras capture images, CCD cameras have less of the infamous “jello effect.” The “jello effect,” more precisely called the “rolling shutter effect,” is a video distortion caused by the intense vibration of the multirotor in flight. The distortion makes the video look all wobbly. Sometimes the rolling shutter effect can be very severe, like in the video below by YouTube user, Raymond Kurr.

The rolling shutter effect happens with CMOS cameras because of the way they capture images. Basically, a CMOS sensor “sweeps” from top to bottom, capturing image data along the way. Because the camera vibrates during flight, it actually moves a tiny bit between the time the camera scans the top of the image and the time it scans the bottom. This tiny shift in the camera’s aim on each video frame causes the rolling shutter effrect.

CCD cameras work differently than CMOS cameras though. Instead of scanning the image, a CCD camera captures the entire frame at once. This is called a “global shutter.” It does not eliminate the jello effect entirely, but it does help a great deal. So, as long as you balance your propellers, and build your multirotor with care, there should be almost no jello effect with a CCD camera.

The second reason CCD cameras are preferable to CMOS cameras for FPV is because they have better performance in extreme lighting conditions. So, for example, with proper settings, a CCD camera can allow the pilot to look directly into the sun and still see the surrounding areas clearly. A CCD camera can also allow pilots to see clearly in low light conditions, like at dusk. The reason CCD cameras perform better in extreme lighting conditions is because they have a higher dynamic range. This basically means that in the images captured by a CCD camera, there is a greater difference between the lightest areas of the image and the darkest than with CMOS cameras.

There are a couple disadvantages to using CCD cameras though. CCD cameras are more complex, and more expensive to build, which means they cost more than CMOS cameras. CCD cameras also use more power; that said the amount of power used by your FPV camera is pretty negligible compared to the amount of power consumed by the motors. CCD cameras are also a bit heavier, and a bit larger, than CMOS cameras. This though is also a negligible difference because FPV cameras with either technology are available in extremely small sizes; the smallest FPV cameras are less than 12mm square.

So, the point of all this is that CCD cameras are clearly superior to CMOS cameras for FPV.

Video encoding standard:  NTSC or PAL

FPV cameras also output in two different formats:  NTSC, and PAL. The decision of which to choose is another non-decision though. Many FPV cameras, and most video transmitters, can accommodate either standard anyway.

There are differences between these two video encoding standards though that you should keep in mind. First, these two standards are used in different parts of the world. NTSC is used in North America, Japan and South Korea. PAL is used in most of Europe, Australia, Africa, and Asia. So you might choose to go with the standard used in your country because other people you work with, other pilots, parts suppliers, competition organizers, clients, and so on, are likely to be more familiar with the regional standard. But, again, most FPV equipment can switch between these two standards, so when you’re picking out parts it really doesn’t matter much.

The more important difference between NTSC and PAL is that PAL offers greater resolution, while NTSC has a higher frame rate:

  • PAL: 720 x 576 @ 25fps
  • NTSC: 720 x 480 @ 30fps

So, if you are more concerned with image quality, you can go with PAL. If you want a more fluid image, NTSC is better.

As mentioned a couple times though, most FPV cameras, transmitters, and displays support both encoding standards. So when you are shopping for FPV equipment, the other factors discussed in this post will have a much greater degree of influence over your decision than video encoding standard.

Field of view (lens focal width)

Now we come to the first real, important decision in the process of choosing a camera for your FPV setup. Field of view basically expresses how big a slice of the world a camera can see. The camera’s field of view is very important because it is a major factor in what you will see in your viewing device of choice (more on that in another article). When shopping for FPV cameras, you will usually have different options for lens focal width, that or you can buy lenses to swap out on your camera that offer different focal widths.

Cameras with different focal widths have different fields of view. You can picture a camera’s field of view as a cone emanating from the camera lens. Cameras with different fields of view will have cones with different angles between the sides.

3.6mm focal width

A lens with a focal width of 3.6mm will give you a field of view of about 90 degrees.

2.8mm focal width

A lens with a focal width of 2.8mm will give you a field of view of about 112 degrees.

The most common focal widths for FPV cameras are 3.6mm and 2.8mm. A camera with a 3.6mm focal width will have a field of view of approximately 90 degrees. Many pilots like this field of view because it is similar to the field of view of the human eye, making the FPV video look very natural. A 2.8mm focal width will give a field of view of about 112 degrees. Some pilots like this wider field of view because it allows them to see more of the area in front of the multirotor. However, a 112 degree field of view can look unnatural, so some pilots dislike it.

It is important to find a camera with a field of view you are comfortable with. The lower the focal length number, the wider the camera’s field of view, so the more of the multirotor’s environment you will be able to see. However, the larger the field of view, the more you will start to notice the “fish eye” effect. Objects in the middle of the view will start to look small and far away while objects at the edges will start to look larger, and curved outward. This, coupled with the fact that large fields of view can look unnatural since the human eye has a field of view of only about 90 degrees, means you will want to strike a balance between seeing more of the surrounding environment and getting a more natural or detailed view.

Fortunately, many FPV cameras have changeable lenses, kind of like DSRL cameras. If you are interested in experimenting with different fields of view, you can pick up one of these cameras, and a couple accessory lenses with different focal widths. Typically, lenses can be easily switched by unscrewing the old lens, and screwing in the new one.

accessory lens

A 3.6mm, screw-in accessory lens.

Camera Resolution

The next very important camera specification to think about is resolution. You are probably familiar with resolution in electronic displays. Resolution determines the detail in an image; it is basically the number of pixels used to represent an image. Higher resolution is what makes a 1080p display look much sharper than a standard-definition display. You are probably familiar with resolution specifications in most cameras as well. Most modern cameras have resolutions specified in megapixels. For example, the Nikon D3100 DSLR camera I use to take many of the photos on this site has a resolution of 14.2 megapixels.

But the resolution of FPV cameras is expressed in units with which you are probably not familiar unless you’ve been shopping for security cameras recently. The resolution of almost all FPV cameras is expressed in “TV lines” (TVL). TVL values measure then number of alternating black and while lines that can be displayed in the image horizontally. The larger the TVL number, the higher the resolution of the camera.

36 TVL

This is about 36 TVL.

108 TVL

This is about 108 TVL.

FPV cameras are available in a wide range of resolutions, from about 300 TVL up to 700 TVL. The reason you don’t see resolutions of TVs or cameras expressed in TV lines at your local electronics retailer is because these units were phased out by high-definition display technology. If you go shopping for TVs now, you will see resolutions expressed as 720p, 1080p, or maybe even 4K. But, these resolutions are, in fact, using TVL units, its just few people realize it. A 1080p TV has 1080 horizontal TV lines. A 4K TV has 3840 TV lines. So you can see that the lowest level of high-definition display technology, 720p, is roughly equivalent to a 700 TVL FPV camera.

Just like with TVs though, the higher the resolution of the FPV camera, the most expensive it will be. So while it might be tempting to go for a top-quality 700 TVL camera, keep in mind that it will cost about six times as much as a 500 TVL camera. That said, your FPV camera is not a bad place to splurge a bit in your multirotor budget. Again, the camera is probably the most important part of your multirotor’s FPV setup in terms of the quality of your FPV experience.

Camera size

The last thing to keep in mind when choosing an FPV camera is the camera’s size. Some multirotor frames or camera gimbals will only accommodate cameras up to a certain size. For example, the Quanum Venture FPV Quad-Copter frame (about which I wrote a build guide recently) will only accommodate a camera up to 30mm square. So you will want to make sure the camera you pick will work with your multirotor frame.

FPV Plus Recording

There is one more thing you might want to consider when choosing a camera for FPV. If you are interested in recording video or taking photographs with your multirotor, there are basically two different setups you can choose.

First, you can do what many people do and put two cameras on your multirotor. You would have one camera for FPV, chosen according to all the above discussion, and a separate camera for recording video. There are, of course, some benefits and some drawbacks to this setup. This setup is good because you will not have lag in your video feed, you can use an FPV camera with a wider field of view than you would want for recording, and you can get a very high quality camera for recording. The downsides include the added cost of buying two separate cameras, the added complexity, the added weight on your multirotor, and the fact that the recording camera will not see exactly what your FPV camera is seeing.

Alternatively, you can get a single camera capable of recording and delivering FPV video feed at the same time. You can use something like a GoPro or Mobius camera for this, coupled with some kind of adapter linking the camera to the video transmitter. Using an action camera as your FPV and recording solution is good because it reduces cost, complexity and weight, but it can also be problematic because, especially on older GoPro cameras, there can be some lag between reality and what you are seeing on your FPV screen. This is because the camera’s processor has to handle capturing video and outputting video.

A way around this lag issue is using a specialized FPV camera designed specifically for multirotor aircraft which is intended for simultaneous FPV transmission and video recording. Probably one of the most popular of these types of cameras is the PilotHD from Fat Shark. Cameras like the PilotHD connect to video transmission equipment on the multirotor without any kind of adapter and are designed specifically to avoid lag in the FPV feed. They are also designed to be small, light weight, and tough so that they can survive a crash. The downside is that the video quality of these cameras is not quite as good as something like a GoPro or Mobius camera. The PilotHD records 720p at 30fps whereas the newest GoPro cameras can record in 4K.