Although a high-speed camera is defined by its exceptionally high frame rate, there are a few other factors to consider before buying a high-speed camera.
While common video cameras use 24 to 40 frames per second (fps), a high-speed camera uses CCD or CMOS image sensors to capture high-speed objects at frame rate ranging from 500 fps to 1,000,000 fps.
However, there are several other factors to consider while purchasing a high-speed camera, as they might influence the quality of the video captured. Different applications require different specifications, hence, a thorough knowledge of them would help in making the right decision. Here are the different factors of a high-speed camera.
While purchasing a high-speed camera, one must be aware of the potential throughput that the camera can achieve. It can be calculated by multiplying the maximum resolution by the maximum frame rate at that particular resolution.
It is the most important factor to consider while purchasing a high-speed camera, as applications need a combination of both resolution and frame rate.
The growth in the throughput of high-speed cameras exhibits the exponential technological growth of Moore’s law more than in any other single camera specification.
A high-speed camera is, first and foremost, defined by its high frame-rate. Before capturing a high-speed event, the required frame rate is chosen and the resolution is adjusted based around the available options and the region of interest.
Cameras featuring high-frame rate are increasingly entering the realm of consumer-grade electronics like smartphones and consumer cameras. While such cameras only provide frame rates of 120-140 fps, high-speed cameras start around 500 fps and go up to 1,000,000 fps.
According to a report by Allied Market Research, the frame rate of 1,001 – 10,000 fps is poised to grow at the highest CAGR of 8.9% from 2018 to 2025.
The report also estimates that the overall global high-speed camera market would reach $694.8 million by 2025, growing at a CAGR of 7.5%.
The number of pixels available in the camera’s sensor is represented by the camera’s resolution. It determines the detail of the image and the precision with which motion can be calculated.
Most monitors and TV come equipped with 2.1 Megapixels, or 1920 x 1080 (width x height), or 1080p. One can digitally zoom in on an area of interest of a high-resolution image without losing significant details. It also allows for a much wider choice of potential aspect ratio.
Although the resolution is directly linked with the frame rate of the camera, the only fixed values are the number of pixels transferred and the number of pixels on the image sensor. Thus, as long as the horizontal and vertical resolution is not exceeded, the image can be of different sizes.
Shutter speed is also known as “exposure time”, and is calculated by the amount of time a camera shutter is open to expose the camera’s sensor to light. Capturing low-light images require longer shutter speed, while fast-moving objects are best captured by shorter shutter speeds to avoid motion blur.
In applications such as ballistics testing, which require very high frame rates and very little motion blur, shutter speed is an important aspect. Capturing a shot with 500,000 fps and a 4x shutter speed will result in a crisp and un-blurred image than with 1,000,000 fps and 1x shutter speed.
As compared to a monochrome camera, a color camera will generate more colorful, prettier, and interesting shots. However, they come equipped with multiple filters, including Bayer filter, an optical low pass filter, and an IR cut filter.
They block light in some way or form and decreases the quality of the video. However, a black-and-white monochrome imager will not only produce a brighter and crisper image but also one that’s accurate. Hence, it’s advisable to opt for a monochrome camera if your application is leaser based, near-IR based, or low-light based.
Although myriad factors affect the light sensitivity of the camera, a general rule of thumb is that a larger resolution sensor is less sensitive to light than a smaller resolution sensor, as each individual pixel is smaller in size and has fewer photons hitting it at any given time.
While opting for a high-speed camera, it’s advisable to not decide based on the ISO value, an archaic industry standard that hasn’t been updated for modern digital sensors. Instead, comparing the shots of two cameras with similar settings can provide a better objective criterion.
Finally, there are cameras that can offload the video at the same or faster speed than it is captured, and those that capture an entire event first and offloads it later at a much slower speed.
It’s advisable to choose one that meets the requirement, as long-record events and transient events necessitate different capture methods.