FPV cameras are small, lightweight and cheap, and are mounted onto your aircraft to send real-time video back down to you via a video transmitter. FPV stands for First Person Viewing. An FPV camera must provide a live analog video feed to the pilot such that the pilot can maneuver his drone. The video feed from this FPV camera is going to help the pilot to fly. FPV camera’s come in all shapes and sizes.
In order to make your task easy, I will discuss all the things you need to care about when choosing, and using FPV camera
1. Imaging Sensor- CCD or CMOS
2. Form Factor
3. Aspect Ratio
4. Latency
5. Input Voltage
6. Field of View
7. Video Encoding Format- NTSC or PAL
8. TVL- Camera Resolution
9. Wide Dynamic Ranging (WDR)
1. Imaging Sensor- CCD or CMOS
CCD (charge-coupled device) and CMOS (complementary metal oxide semiconductor) sensors are the 2 types of image sensors used in FPV cameras where they mostly vary by how the image is captured by the sensor placed in the FPV camera. FPV cameras convert light signals into electrical signals so that they can be transmitted by the analog video transmitters.
Both CCD and CMOS image sensors start by capturing the image and converting the image into digital signals. The next step is to read the value (electrons or charge accumulated by the camera). This is where the similarities between the two end. The major difference is how the electrical signal is processed and outputted.
In a CCD image sensor, the electrical signal is transported across the chip and are read at one of the corners of the array. The electrical charge from the line of pixels is transferred to the next until all the pixel lines have completed outputting.
Unlike the CCD, CMOS sensors read the electrical signals at each individual pixel (A pixel is a tiny dot or square that is part of a digital image). CMOS sensors have individual transistors for individual pixels compared to a few transistors in a CCD sensor.
Another major disadvantage of the CMOS sensors is how they capture the image. CCD sensors use global shutter (captures the image instantaneously) and CMOS sensors use rolling shutter (rolling shutter- capture the image line by line). As CMOS sensor’s output the image line by line, any vibrations may cause the image to distort. This distortion is known as JELLO effect.
If you didn’t understand any of the technical stuff above, know this: CCD image sensor’s creates high quality images and are less susceptible to electrical noise. CMOS tend to have lower light sensitivity while consuming significantly lower power than a CCD image sensor. CMOS also have a lower image quality, but with constant improvements CMOS sensors are trying to catch up with CCD sensors.
2. Form FactorThere are 4 major camera sizes- Standard, Mini, Micro and Nano size. These cameras are categorized based on the mounting holes that help to mount the camera to the frame. Each drone frame is different and support particular camera sizes. Hence it is important to take note the camera size before buying the camera and rather have an incompatible camera that is too large or too small to be used on the frame you intend to use.
1.Standard
The standard size was decided by the Runcam Swift when it was launched back in 2017 with mounting holes 28mm apart. They fit all the larger frames and some medium sized frames as well. They are also used in RC airplane FPV.
2. Mini
Mini sized cameras have 21mm mounting holes that usually fit medium sized frames. Mini sized cameras have become popular these days as they are converted into FPV/HD cameras.
3. Micro
Micro sized cameras are used with ultra-light racing drone frames where saving every gram of weight becomes essential. But don’t be fooled by the size as it can perform as well as the standard sized camera. The mounting holes are 19mm apart.
4. Nano
Nano cameras have no particular mounting options in. They don’t normally come with hard cases such as the standard sized cameras. They are mostly used on 2” or under, sized quads.
3. Aspect RatioThe aspect ratio refers to the image size that is being displayed on a monitor or screen. A 16x9 image format will have a wider and shorter image than a 4x3. The 4x3 image format may appear to be taller. There are FPV pilots who prefer both the 16x9 and 4x3. But it is widely accepted that a 4x3 image format helps in flying better because of the taller image.
But aspect ratio may also depend on the camera and the camera lens. Some FPV cameras support both 16x9 and 4x3 image format. Most CMOS cameras support 16x9 natively, for a CMOS camera to display 4x3 image format, the sides may appear to be chopped from the 16x9 to form a 4x3 image.
4. LatencyFPV cameras require time to capture and process the image. This time taken by the camera to convert an image into electrical signals is known as latency. Lower the latency the better.
Latency may not just be attributed to the camera itself. Video transmitters and the LCD screens in the FPV goggles may also add to the latency.
If you are flying slow and closer to you latency does not pose a major concern for the buyer. But when flying a race quad at 100mph with a 100ms delay from the FPV camera, the drone is 4m ahead giving you no time to react and correct on your inputs.
That’s the theory, most modern FPV cameras have as little as 10ms delay time. With constant improvements cameras such as the Foxeer Predator V3 have as little as 4ms latency.
5. Input VoltageInput voltage refers to the range of voltages that can be safely supplied for the safe operation of the camera. A well built FPV camera will support a wide range of voltages with most modern cameras having voltage supports of up to 35v. The camera’s have an in built linear BEC that steps down the voltage to 3.3v (the internal working voltage of the electronics inside the cam is 3.3v).
Input voltage refers to the range of voltages that can be safely supplied for the safe operation of the camera. A well built FPV camera will support a wide range of voltages with most modern cameras having voltage supports of up to 35v. The camera’s have an in built linear BEC that steps down the voltage to 3.3v (the internal working voltage of the electronics inside the cam is 3.3v).
It is not recommended to supply a large voltage for the camera as it has a lower operating voltage internally. Higher the input voltage harder the BEC works to step down that voltage. Supplying a lower voltage also keeps the camera cooler comparatively.
So it is recommended to supply a lower input voltage. Most modern FC’s have filtered voltage supplies dedicated for FPV camera, so it is worth taking a look at the FC you are going to be using. Voltages within 12v is considered nominal.
6. Field of ViewField of view (FOV) refers to the observable area captured by the camera. The camera’s lens size determines the FOV. Smaller the camera lens, larger the FOV.
Larger FOV allows you to see more but that may not necessarily be a good thing. With larger FOV it becomes difficult to observe the minute details such as branches of trees. With our limited vTx’s it becomes much worse. A FOV between 130–150° is considered ideal with a considerable amount of view and exceptional details. The below diagram illustrates a narrow and wide FOV camera.
Video encoding is the process of converting video signals (in our case electrons from the FPV cam) into a format that can be read by monitors (FPV monitors or goggles). This is usually taken care by the FPV camera. The most commonly used video formats are NTSC (National Television System Committee or PAL (Phase Alternating Line).
The main difference between NTSC and PAL is, NTSC has a 720x480 resolution at 30fps and PAL has a 720x576 resolution at 25fps.
NTSC with its higher frame rates allows for a smooth video playback. PAL with its slightly better resolution allows for sharper texts from OSD. But it’s based on your personal preference. Pick a video format that works for you. Since most FPV camera’s support both formats, it’ll be easier for one switch back and forth and pick one that works.
8. TVL- Camera ResolutionTVL stands for TV Lines. TVL is the measure of resolution of analog cameras. A 1000TVL camera can capture 500 Black and 500 White alternating lines in one frame.
Wide dynamic ranging is the fancy word referring to the camera’s ability to capture the bright and dark parts of an image. Dynamic range is the difference between the darkest and the brightest parts of an image.
WDR comes into picture when you fly outdoors where the sun casts shadows and becomes less of a factor when flying on cloudy days. An Overexposed image is where the brighter parts of the image is blownout and an underexposed image is where the darker parts of the image appears even darker.
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