# What is the fastest possible shutter speed?

Is there a theoretical maximum at which a shutter cannot go faster (aside from the speed of light :-))?

Is there a camera which has the fastest shutter speed? What is the advantage of this?

• May be of interest Ramesh Raskar work on femto photography: web.media.mit.edu/~raskar//trillionfps – Eliseo Ocampos Aug 27 '13 at 22:39
• Casio Exilim Pro EX-F1 records movies at 1200 frames per second and has maximum shutterspeed of 1/40000 sec. So it can get quite fast already at consumer level without a need to go into special high-price range. – Esa Paulasto Aug 28 '13 at 12:18
• Hey, kids, A colleague of ours (Eleftherios Goulielmakis) at CERN has developed an exposure time of a yactosecond earlier this year. That's an exposure time of 1/10000000000000000000000000 sec. (24 of 'em). – Stan Aug 31 '13 at 20:25

If you are not limiting the question to mechanical shutter, the fastest shutter speed I ever saw in a machine vision camera was 1 micro second, taking pictures at 775.000 frames/s. The advantage is to analyse high speed actions, like grains flying fast in during processing, studying physics, tennis balls hitting rackets, other types of impact. To achive blazing fast FPS you need a shutter to match. 25fps needs a max shutter length below 40ms. 100 fps needs less than 10ms etc. Also looking at the sun, burning things and solder actions, lasers without ND filters could be applications, but then you need to evaluate if it is a problem to use ND filters instead of using a \$100.000 camera.

There is no fastest speed shutter. The fastest theoretically possible would be the time it takes for however many photons you want to capture to hit the sensor. The advantage is that it stops motion. You can see what happened during a very small moment in time and thus a very fast action. The trick is to have sufficient light though. You need sufficient photos to strike the sensor during the exposure in order to be able to make out the details of what you are looking at.

The amount of light you need increases proportionally to the shutter speed with a fixed factor of the sensitivity of the sensor. Each time the speed of the shutter gets twice as fast, you need twice as much light for a given sensor to be able to expose an image. This leads to practical limits with existing technology, but there is no particular physical limitation to shutter speed given enough light and a fast enough sensor.

I'd like to point out that a shutter is not a neat "on," "off" thing. The shutter speed is an indication of the exposure duration, only, from half open to half closed. The "halfway point" is called "half-peak" by some.

In other words, the shutter takes time to get from fully closed to it's fullest opening, remain at it's fullest opening, and time to get the shutter from it's open position, back to it's fully closed position.

Then, there's the question of accuracy, and repeatability to the indicated setting. Apertures can be exact whereas shutter speeds rarely are.

• That really depends on the type of shutter in question, if there is even a mechanical shutter at all. With a two curtain type shutter as is almost universal in DSLR cameras, no part of the film/sensor is exposed longer than any other part as long as the second curtain takes the same amount of time to cross the image plane when covering it back up as the first curtain did when uncovering it. – Michael C Aug 30 '13 at 17:45
• @Michael Clark Yes. I know of no high-speed shutters that use curtains. Segmented wheels, prisms, etc. At some point, traveling slits are not employed. Well, none that I've known about. The slit cameras I've used, the slit was fixed and the film traveled past it at speed. – Stan Aug 30 '13 at 21:04
• @ Michael Clark There's more. In addition to your "as long as the second curtain…" is the acceleration and deceleration of the curtain. There is a measurable hysteresis error for slit exposure in addition to the difficulty of the lag between the beginning and the ending of the exposure. Shutter curtain direction of travel errors make some kinds of illumination and/or motions problematic. High speed linear travel can become distorted with different relative travel direction. – Stan Aug 31 '13 at 8:06