Have you ever wondered what frame rates really are? While the concept might be tricky, in fact it simple to understand. The answer lies in the fundamental concept of video. Back in the old days instead of video it has been used the denomination “motion picture.” This term tells a lot about what frame rates are. When you are recording video, you are taking in fact a series of pictures that are stitched together.
When you view the pictures at a certain rate it creates the illusion of motion. Our eyes and brain are not able to process this amount of images. Consequently your brain will interpret these images as a real movement.
Based on the facts presented so far we can conclude that frame rate the frequency (rate or speed) at which images are displayed. Frame rates are expressed usually in frame rates per second. There are several frame rates that can be used. Let’s check out which are these.
The 24 fps is a standard frame rate and is widely used. This frame rate is a standard frame rate for the film industry. We associate the 24 fps with the expression “cinematic look”. While not everybody is able to distinguish this frame rate from the other. The vast majority of video cameras will offer you the possibility to shoot 24 fps. In fact the 24 fps is really 23.976 fps. This is due to NTSC video compatibility, but the difference is more for transfer purposes.
Regarding the 25 FPS, there is not much to tell. It is very similar to the 24 FPS and it is a European standard. This derives from the PAL television standard and it is very similar to 24 FPS regarding the cinematic qualities.
The 30 FPS is technically 29.976 NTSC video standard. While the 24/25 FPS is associated with cinematic, this frame rate is NOT considered a cinematic frame rate. The reason lies in the increased number of frames that are displayed. Because of that the image is much more crisp and sharp.
This frame rate is mainly used for broadcasting purposes. Most of the television broadcasts are using this frame rate because you get a much smoother look. Action and movement are much easier to follow at this frame rate.
The are high definition rates of the 24/25 FPS. The double amount of frame rates reduce motion blur and flicker. Videos shot at 48 FPS or 50 FPS tend to appear more lifelike. When working with slow motion these two frame rates can be easily converted to 24 or 24 FPS.
Many actual cameras are able to shoot at 60 FPS (or 59.94) and is becoming more and more popular. It might be the future standard for high end broadcast and television. For many DSLRs, the 60 FPS is the best option when it comes to shoot slow motion.
Many high end video cameras are able to shoot with higher frame rates than 60 FPS. It is not uncommon to see frame rates like 120, 240, 480 FPS or even more. But these require some special video cameras.
Instead modern smartphones are very competitive in this domain. They are able to shoot up to 960 fps, but they are limited in the amount of time they can record. Shooting at this high frame rates can have some real benefits. Not only that it allows for better slow motion, it gives you unimaginable insights. You can capture details which cannot be noticed at 60 FPS.
If you are curious what high speed filming can do, please check out the video below.
Interlaced vs Progressive
You will notice that for modern TVs and monitors there is an additional letter, either “i” or “p”. The letter “i” stands for interlaced, while the letter “p” stands for progressive and not “pro”. The difference in these two is the way images are shown.
The progressive scanning will draw all of the lines in a single frame sequentially so that each frame contains a complete image fills the screen.
The interlaced scanning only every other line is displayed in one frame. This technology is not new. In fact the information can be dated back from the age of CRT television where everyone was watching either 480i or 576i.
Even today you can find 1080i monitors available on the market. While it would be straight forward to display one full image instead of every other line, this has some issues. First of all the technology back in the days of old CRT TV’s did not allow the transmission of the amount of data on coaxial cable. Secondly interlaced scanning saves bandwidth by sending half of the frame at once.
While this sounds good on paper, interlaced scanning has some down sides. It is prone for artifacts.