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An intervalometer, also called an interval meter or interval timer, is a device that measures short intervals of time. [1] [2] People commonly use such devices to signal, in accurate time intervals, the operation of some other device. The intervalometer measures the intermittent pulses between a starting pulse signal and an ending pulse signal, before a pulse counter measures the number of pulses released into the appropriate time interval. [3] For instance, an intervalometer might activate something every 30 seconds.
Photographers use intervalometers to trigger exposures. Photographers often do this for a time-lapse series, or to take or begin taking picture after a set delay.
Examples of intervalometer use in aerial photography include delaying the start of picture taking by an unattended camera until some time after takeoff and separating multiple exposures in time, and thus distance as the vehicle containing the camera travels, to obtain the 3D effect (stereoscopy). To obtain the 3D effect each image should have about 60% of the surface in common with either the preceding or following image. The interval is calculated as a function of the altitude and speed of the vehicle; shorter intervals for low altitude and high speed.
Often the purpose of a photographic intervalometer is to reduce the resources required either to take the pictures or post-process them as similar images could be obtained by having the camera continuously take pictures as rapidly as possible. Using an intervalometer permits restricting the pictures taken to only those with the desired content. This reduces the requirements for resources such as power and storage media (e.g. film or memory card space).
Most digital single-lens reflex (DSLR) cameras are limited to 30 second or shorter exposures. An intervalometer can control long (>30 seconds) or very long exposures (minutes or hours) using the "Bulb" setting. Long and very long exposures taken at night can be combined to create time-lapse animations, including star trails. Astrophotographers can use processing techniques with such exposures to create images of deep-sky objects in the night sky, like nebulae and galaxies.
Most modern cameras include the most basic intervalometer functionality, the "self-timer". This delays the shutter release for a short time, allowing the photographer to get into the picture, for example.
In the past, intervalometers were external devices that interfaced to a camera shutter to take a picture, or series of pictures, at a set time. These sometimes used existing remote shutter features on cameras. Later, standalone products commonly referred to as intervalometers added capabilities beyond the basics of just measuring, and signaling, a time interval. One of the first added features was the ability to use an external event to signal the start of the time intervals. The ability to sense an external event is such a common feature of intervalometer products that many people do not distinguish between the sensing of the event and the measuring of time intervals.
What is meant when someone refers to an "intervalometer" must be determined from context. Some possibilities are: time-lapse capability (strictly an intervalometer function), sensing of a remote event, a time delay longer than what most consider the "self-timer" range, etc. Strictly speaking, an intervalometer only measures, and/or signals, time intervals.
Almost all digital cameras have basic intervalometer functions—current and elapsed times. More advanced functions are a matter of what the manufacturer chooses to implement in the camera's firmware. Functions beyond the self-timer are beginning appear in some digital cameras, and often distinguish between similar models in a camera line.
The ALE-39 countermeasures system uses intervalometers manufactured by Ledex Inc. (now part of Johnson Electric) of Dayton, Ohio. The ALE-39 fires flares in a synchronized pattern, rapidly and with great reliability. The intervalometer in the ALE-39 is essentially a solenoid-actuated rotary switch driven by a separate programmer, which gives timing intervals and channel enabling to either of one or two channels. Intervalometers that contain internal interval clocks include the Lau-68, Suu-13 and similar electromechanically sequenced switches. Safety is provided to unfired outputs by maintaining a ground connection to all except the output being selected for firing; i.e., providing an electrical pulse to the firing squib.
Bomber aircraft can release all bombs at once ("salvo") or drop individual bombs at intervals. A bombardier who selects the latter can program an intervalometer to control the rate of bomb release, which determines how far apart they land in the target area.
Common intervalometers in homes include timers that turn lights on and off at set times, or controllers for automatic sprinkler system. People use these devices when they leave home for an extended period, to make it appear the home is occupied. There are also a large number of commercial and industrial applications for even such basic intervalometers.
A camera is an optical instrument used to capture and store images or videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photography and videography, cameras have played a significant role in the progression of visual arts, media, entertainment, surveillance, and scientific research. The invention of the camera dates back to the 19th century and has since evolved with advancements in technology, leading to a vast array of types and models in the 21st century.
A flash is a device used in photography that produces a brief burst of light at a color temperature of about 5500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene. Other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the electronic flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs and flammable powders. Modern cameras often activate flash units automatically.
A waveform monitor is a special type of oscilloscope used in television production applications. It is typically used to measure and display the level, or voltage, of a video signal with respect to time.
In photography, bracketing is the general technique of taking several shots of the same subject using different camera settings, typically with the aim of combining the images in postprocessing. Bracketing is useful and often recommended in situations that make it difficult to obtain a satisfactory image with a single shot, especially when a small variation in exposure parameters has a comparatively large effect on the resulting image. Given the time it takes to accomplish multiple shots, it is typically, but not always, used for static subjects. Autobracketing is a feature of many modern cameras. When set, it will automatically take several bracketed shots, rather than the photographer altering the settings by hand between each shot.
A timer is a specialized type of clock used for measuring specific time intervals.
A camera phone is a mobile phone which is able to capture photographs and often record video using one or more built-in digital cameras. It can also send the resulting image wirelessly and conveniently. The first commercial phone with color camera was the Kyocera Visual Phone VP-210, released in Japan in May 1999.
In photography and cinematography, a multiple exposure is the superimposition of two or more exposures to create a single image, and double exposure has a corresponding meaning in respect of two images. The exposure values may or may not be identical to each other.
The science of photography is the use of chemistry and physics in all aspects of photography. This applies to the camera, its lenses, physical operation of the camera, electronic camera internals, and the process of developing film in order to take and develop pictures properly.
Chronophotography is a photographic technique from the Victorian era which captures a number of phases of movements. The best known chronophotography works were mostly intended for the scientific study of locomotion, to discover practical information for animal handlers and/or as reference material for artists. Although many results were not intended to be exhibited as moving pictures, there is much overlap with the more or less simultaneous quest to register and exhibit photographic motion pictures.
Time-lapse photography is a technique in which the frequency at which film frames are captured is much lower than the frequency used to view the sequence. When played at normal speed, time appears to be moving faster and thus lapsing. For example, an image of a scene may be captured at 1 frame per second but then played back at 30 frames per second; the result is an apparent 30 times speed increase. Similarly, film can also be played at a much lower rate than at which it was captured, which slows down an otherwise fast action, as in slow motion or high-speed photography.
A rotary disc shutter is a type of shutter. It is notably used in motion picture cameras. Rotary shutters are semicircular discs that spin in front of the film gate, alternately allowing light from the lens to strike the film, or blocking it.
When setting photoflash exposures, the guide number (GN) of photoflash devices is a measure photographers can use to calculate either the required f‑stop for any given flash-to-subject distance, or the required distance for any given f‑stop. To solve for either of these two variables, one merely divides a device's guide number by the other.
In photography, a shutter is a device that allows light to pass for a determined period, exposing photographic film or a photosensitive digital sensor to light in order to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as seen in a movie projector or a signal lamp. A shutter of variable speed is used to control exposure time of the film. The shutter is constructed so that it automatically closes after a certain required time interval. The speed of the shutter is controlled either automatically by the camera based on the overall settings of the camera, manually through digital settings, or manually by a ring outside the camera on which various timings are marked.
A self timer is a device on a camera that gives a delay between pressing the shutter release and the shutter's firing. It is most commonly used to let the photographer to take a photo of themselves, hence the name.
Digital photography uses cameras containing arrays of electronic photodetectors interfaced to an analog-to-digital converter (ADC) to produce images focused by a lens, as opposed to an exposure on photographic film. The digitized image is stored as a computer file ready for further digital processing, viewing, electronic publishing, or digital printing. It is a form of digital imaging based on gathering visible light.
Autobracketing is a feature of some more advanced cameras, whether film or digital cameras, particularly single-lens reflex cameras, where the camera will take several successive shots with slightly different settings. The images may be automatically combined, for example into one high-dynamic-range image, or they may be stored separately so the best-looking pictures can be picked later from the batch. When the photographer achieves the same result by changing the camera settings between each shot, this is simply called bracketing.
The Harris shutter is a strip device with three color filters, invented by Robert S. "Bob" Harris of Kodak, for making color photographs with the different primary color layers exposed in separate time intervals in succession. The term Harris shutter is also applied to the technique or effect.
The following outline is provided as an overview of and topical guide to photography:
Most digital cameras support the ability to choose among a number of configurations, or modes for use in various situations. Professional DSLR cameras provide several manual modes; consumer point-and-shoot cameras emphasize automatic modes; amateur prosumer cameras often have a wide variety of both manual and automatic modes.
A star trail is a type of photograph that uses long exposure times to capture diurnal circles, the apparent motion of stars in the night sky due to Earth's rotation. A star-trail photograph shows individual stars as streaks across the image, with longer exposures yielding longer arcs. The term is used for similar photos captured elsewhere, such as on board the International Space Station and on Mars.