Understanding Slow Motion Video

Matches burn after we strike the side of a matchbox or the side of our scruffy beards. However, this giant match was lit by a torch and it was captured at 4,000 frames per second. If you want to learn about the amazing chemical reaction taking place go here. But if you want to learn a out how they managed to capture it burning in slow motion, you've come to the right place. 

They said that they used 2,000 watts of light at 4 inches plus mirrors and reflectors in order to capture the burning flame in slow motion. Isn't that going to overexpose the match and flame? Isn't the flame itself going to be a sufficient amount of light anyway? Nope.

Even though the flame is producing a seemingly sufficient amount of light, it's not enough to be captured at 4,000 frames per second. As you increase framerate, the amount of light that is required to capture a subject is also increased. If the framerate were reduced to a standard of 24 fps or 30 fps, 2,000 watts of light at 4 in would be overkill and completely overexpose the subject because the frequency at which an image is being captured has decreased.

Another factor is shutter speed. As a general rule, shutter speed is "double" that of a given frame rate to produce a decent looking shot. This is of course completely subjective. A shot captured in 24 fps would then have a shutter speed of 1/48 and a shot captured in 30 fps will have a shuttle speed of 1/60. If they shot at 4,000 fps then they may not have set their shutter speed to a high number. Most of the time it's electronically controlled on a high speed camera. Shutter speed ultimately decreases the amount of light that is captured as the fraction of the shutter speed decreases. Technical mumbo-jumbo aside, it's really cool to watch things in slow motion.

Via: Inscider
By: Alex Zarnoski | @ajazz16 | Ajazz Tech