High-speed photography is the science of taking pictures of very fast phenomena. In 1948, the Society of Motion Picture and Television Engineers (SMPTE) defined high-speed photography as any set of photographs captured by a camera capable of 128 frames per second or greater, and of at least three consecutive frames. High-speed photography can be considered to be the opposite of time-lapse photography.
In common usage, high-speed photography may refer to either or both of the following meanings. The first is that the photograph itself may be taken in a way as to appear to freeze the motion, especially to reducemotion blur. The second is that a series of photographs may be taken at a high sampling frequency or frame rate. The first requires a sensor with good sensitivity and either a very good shuttering system or a very fast strobe light. The second requires some means of capturing successive frames, either with a mechanical device or by moving data off electronic sensors very quickly.
Other considerations for high-speed photographers are record length, reciprocity breakdown, and spatial resolution.
The first practical application of high-speed photography was Eadweard Muybridge's 1878 investigation into whether horses' feet were actually all off the ground at once during a gallop. The first photograph of a supersonic flying bullet was taken by the Austrian physicist Peter Salcher in Rijeka in 1886, a technique that was later used by Ernst Mach in his studies of supersonic motion.[1] German weapons scientists applied the techniques in 1916.[2]
Bell Telephone Laboratories was one of the first customers for a camera developed by Eastman Kodak in the early 1930s.[3] Bell used the system, which ran 16 mm filmat 1000 frame/s and had a 100-foot (30 m) load capacity, to study relay bounce. When Kodak declined to develop a higher-speed version, Bell Labs developed it themselves, calling it the Fastax. The Fastax was capable of 5,000 frame/s. Bell eventually sold the camera design to Western Electric, who in turn sold it to theWollensak Optical Company. Wollensak further improved the design to achieve 10,000 frame/s.
Redlake Laboratories introduced another 16 mm rotating prism camera, the Hycam, in the early 1960s.[4] Photo-Sonics developed several models of rotating prism camera capable of running 35 mm and 70 mm film in the 1960s.Visible Solutions introduced the Photec IV 16 mm camera in the 1980s.
In 1940, a patent was filed by Cearcy D. Miller for the rotating mirror camera, theoretically capable of one million frames per second. The first practical application of this idea was during the Manhattan Project, when Berlin Brixner, the photographic technician on the project, built the first known fully functional rotating mirror camera. This camera was used to photograph early prototypes of the first nuclear bomb, and resolved a key technical issue about the shape and speed of the implosion,[which?] that had been the source of an active dispute between the explosives engineers and the physics theoreticians.
The D. B. Milliken company developed an intermittent, pin-registered, 16 mm camera for speeds of 400 frame/s in 1957.[4]Mitchell, Redlake Laboratories, and Photo-Sonics eventually followed in the 1960s with a variety of 16, 35, and 70 mm intermittent cameras.
Harold Edgerton is generally credited with pioneering the use of the stroboscope to freeze fast motion.[5][6] He eventually helped found EG&G, which used some of Edgerton's methods to capture the physics of explosions required to detonate nuclear weapons. One such device was the EG&G Microflash 549,[7] which is an air-gap flash. Also see the photograph of an explosion using a Rapatronic camera.
Advancing the idea of the stroboscope, researchers began using lasers to stop high-speed motion. Recent advances include the use of High Harmonic Generationto capture images of molecular dynamics down to the scale of the attosecond (10−18 s).[8][9]
There are three types of high-speed film camera;
- Intermittent motion cameras, which are a speed-up version of the standard motion picture camera using a sewing machine type mechanism to advance the film intermittently to a fixed exposure point behind the objective lens,
2.Rotating prism cameras, which pull a long reel of film continuously past an exposure point and use a rotating prism between the objective lens and the film to impart motion to the image which matches the film motion, thereby canceling it out, and
3.Rotating mirror cameras, which relay the image through a rotating mirror to an arc of film, and can only work in a burst mode.[10]
Intermittent motion cameras are capable of hundreds of frames per second. Rotating prism cameras are capable of thousands of frames per second. Rotating mirror cameras are capable of millions of frames per second.
As film and mechanical transports improved, the high-speed film camera became available for scientific research. Kodak eventually shifted its film from acetate base to Estar (Kodak's name for a Mylar-equivalent plastic), which enhanced the strength and allowed it to be pulled faster. The Estar was also more stable than acetate allowing more accurate measurement, and it was not as prone to fire.
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