Is there a limit to the frame rate achievable with a high-speed camera?

A high-speed camera is a device used for recording fast- moving objects as a photographic image(s) onto a storage medium.

A normal motion picture is filmed and played back at 24 frames per second, while television uses 25 frames/s (PAL) or 29.97 frames/s (NTSC). High-speed film cameras can film up to a quarter of a million frames per second by running the film over a rotating prism or mirror instead of using a shutter, thus reducing the need for stopping and starting the film behind a shutter which would tear the film stock at such speeds.

Is it possible for a high-speed camera to shoot video at a speed of 299792458 FPS?

• Speeds are not measured in frames per second. A frame rate of 299792458 1/s has absolutely nothing to do with speed of light. – Johannes Sep 20 '14 at 18:18
• – lemon Sep 20 '14 at 18:29
• @lemon - I am old enough to remember the time that SCIAM was considered a quality pop science journal. How times have changed! That is the worst title imaginable for the content discussed. – Johannes Sep 20 '14 at 18:40
• @Achmed - would it be an idea to reword the title? I guess your intention is to ask if frame rates are achievable that allow recording the propagation of a light pulse? Or did you literally have in mind to ask about the feasibility of a 0.3 billion FPS? – Johannes Sep 20 '14 at 19:34
• @Johannes infact I want to know about limits of HSC (High Speed Camera). for example, How fast a HSC can Shoot? – Achmed Sep 20 '14 at 23:08

5 Answers

Is it possible for a high-speed camera to shoot video at a speed of 299,792,458 FPS?

No, not in any practical sense. The mechanics of keeping the frame rate constant to within 9 significant digits or about 0.0033 ppm (parts per million) in your case is out of reach of anyone that has to ask.

3.3 ppb? Really? What is the need for such extreme accuracy?

Is it possible for a high-speed camera to shoot video at 299,792,458 FPS?

A rate of 299,792,458 frames per second would create a movie in which, between subsequent frames, light illuminating the scene happens to propagate one meter. So nothing really special occurs at this particular frame rate, and no laws of physics prohibit a camera shooting at this rate. In fact, recordings at a thousand times higher frame rate have been achieved, allowing the researchers to closely follow the propagation of a light flash over a tabletop scene.

Is there then no limit whatsoever on frame rates that can be achieved? One should note that for visible light a frame rate of 500 trillion per second (a thousand times higher than currently achieved) would correspond to a single optical cycle. In other words, one would need to accommodate UV and higher frequency electromagnetic radiation to pass the petaframe-per-second limit.

As an aside: femtosecond 'camera flashes' (generating light flashes of no more than a few optical cycles) already exist.

• That link to the "recordings at a thousand times ..." is to work that is done with multiple exposures with slightly varying shutter offset on each subsequent exposure and NOT actually being run at that frame rate. Much like Doc Edgerton and his fast strobe movies. – placeholder Oct 26 '14 at 15:58
• Even so it is a really cool idea. – mmesser314 May 15 '15 at 13:35

The fastest high speed camera that I am aware of is the Hadland Imacon 200. This camera is capable of recording 16 sequential frames at a rate of (approximately) 200 Mfps. That means it takes one picture every 5 ns - during which time light only travels 1.5 m! This is a "true" camera in the sense that it can acquire a burst of 2D images; not to be confused with the sampling cameras that require accurately pulsed laser sources to build up an image of a repeating event, this is the kind of camera that will record a one-time event, like a bullet hitting a target. Note that a fast bullet (2000 m/s) will travel 10 µm in 5 ns - less than the width of a human hair. It is indeed about as fast as you ever need to go to film macroscopic one-time phenomena.

I found the following blurb on the Photonics Spectra website

The Imacon 200 offers a simultaneous framing and streak recording option for analysis of complex, ultrafast transient events such as laser ablation. This digital imaging system from DRS Hadland Ltd. has a patented multichannel beamsplitter and a retriggerable CCD chip that extends the number of discrete images captured to 16. One or two streak channels can be incorporated into the camera. The Imacon 200 is capable of data acquisition rates of up to 200 million fps when it is referenced to a 200-MHz quartz crystal clock.

A more detailed description can be found on the vision-systems.com website

The key to this system is the image intensifier that amplifies the signal: for such short frame rates, it is hard to get sufficient light from the sample. One typically uses a flash gun that is triggered just before the event of interest, then fires the camera during the event. It is mind boggling to think that a 1 µs flash (extremely fast... most consumer flash guns are 1/1000 to 1/20,000 of a second, so 50 - 1000x slower) has to be "turned on, then wait a bit, then take the pictures". It reminds you how crazy fast this is.

A slightly older series of Imacon cameras had a single phosphor, and the electrons from this were accelerated and deflected electronically. But such phosphors are not fast enough at these rates, which is why they have gone to the optical beamsplitter followed by image intensifiers (MCP - multi-channel plates).

(image from the above-linked article on vision-systems.com)

Older, slower film cameras with stationary film (like the C4 used to image the first atomic bomb tests) use a rotating mirror with a pair of relay lenses (one per frame) to get to their frame rate.

The insides of such a camera had to be evacuated (or at least depressurized) in order to get the mirror up to speed and prevent pressure waves from distorting the image. You can see a description here - this is also the source of the above picture. The film used in these cameras is not "off the shelf", because it has a slight curve in it in order to accommodate the optical path. It therefore was cut from huge rolls of (ordinary, wide) film used for aerial photography - the only film stock wide enough to permit the cutting of an arced segment. After a single shot exposure, you had to develop the film... and had to hope all the triggering happened in the right sequence!

Simply, no. We can not get film to travel near the speed of light. That said, you could record a packet of light, thus "record" light, using another technique. If I understand it right, they re-expose the "film" over and over again. They do this some thousand times and each exposure adds more brightness until the images becomes visable. I do believe the first guys to do this recorded it digitally.

Frames per second and meters per second are fundamentally different units, and comparing their numbers is a textbook example of comparing apples to oranges.

What if I measure light in miles per second: $186{,}000\ \mathrm{miles/sec}$? Or centimeters per second: $3\times10^{10}\ \mathrm{cm/s}$? Which framerate do you take correspond to the "speed of light": $3\times10^8$, $186{,}000$, or $3\times10^{10}$? There is no answer because the question doesn't make sense. It is akin to asking how much distance is in a frame.

There is no hard upper limit on the framerate of a camera.

By the way, there are some popular videos and Nobel prizes given out to recording things at extremely high framerates (billions of times per second or faster), but these are cheating. They don't take that many frames in any given second. Rather, they repeat the scene billions or more times, each time taking an image with a (very precisely known) delay after the start of the scene. They then string all this data together as though each image were taken one right after another.