Flash

Flash

Making a Flash
A basic camera flash system, like you would find in a point-and-shoot camera, has three major parts.
A small battery, which serves as the power supply
A gas discharge tube, which actually produces the flash

A circuit (made up of a number of electrical components), which connects the power supply to the discharge tube
The two components on the ends of the system are very simple. When you hook up a battery's two terminals to a circuit, the battery forces electrons to flow through the circ

uit from one terminal to the other. The moving electrons, or current, provides energy to the various things connected to the circuit (see How Batteries Work for more information).

The discharge tube is a lot like a neon light or fluorescent lamp. It consists of a tube filled with xenon gas, with electrodes on either end and a metal trigger plate at the middle of the tube.

This is the metal trigger plate's job. If you briefly apply a high positive voltage (electromotive force) to this plate, it will exert a strong attraction on the negatively charged electrons in the atoms. If this attraction is strong enough, it will pull the electrons free from the atoms. The process of removing an atom's electrons is called ionization.

The free electrons have a negative charge, so once they are free, they will move toward the positively charged terminal and away from the negatively charged terminal. As the electrons move, they collide with other atoms, causing these atoms to lose electrons as well, further ionizing the gas. The speeding electrons collide with xenon atoms, which become energized and generate light (see How Fluorescent Lamps Work for more information).


To accomplish this, you need relatively high voltage (electrical "pressure"). It takes a couple hundred volts to move electrons between the two electrodes, and you need a few thousand volts to introduce enough free electrons to make the gas conductive.

A typical camera battery only offers 1.5 volts, so the flash circuit needs to boost the voltage substantially. In the next section, we'll find out how it does this.

Telephoto lens

In photography and cinematography, a telephoto lens is a specific construction of a long focal length photographic lens in which the physical length of the lens is shorter than the focal length. In these lenses the optical centre lies outside of its physical construction, such that the entire lens assembly is between the optical centre and the focal plane. A regular lens of a focal length that is longer than what is considered a normal lens is not necessarily a telephoto lens. A telephoto lens has to incorporate a special lens group known as a telephoto group (see below); nevertheless, non-telephoto lenses of long focal length are often informally referred to as telephoto lenses. The angle of view created by a telephoto lens is the same as that created by an ordinary lens of thesame specified focal length.

canon telephoto lens

nikon 70-200 vr

wide angle lens

From a design perspective, a wide angle lens is one that projects a substantially larger image circle than would be typical for a standard design lens of the same focal length; this enables either large tilt & shift movements with a view camera, or lenses with wide fields of view.

More informally, in photography and cinematography, a wide-angle lens refers to a lens whose focal length is substantially shorter than the focal length of a normal lens for the image size produced by the camera, whether this is dictated by the dimensions of the image frame at the film plane for film cameras (film format)[1] or dimensions of the photosensor for digital cameras.

By convention, in still photography, the normal lens for a particular format has a focal length approximately equal to the length of the diagonal of the image frame or digital photosensor. In cinematography, a somewhat longer lens is considered "normal".[2]

There is an easy formula for calculating the angle of view for any lens that produces a rectilinear image. In addition to giving a wider angle of view, the image produced by a wide-angle lens is more susceptible to perspective distortion than that produced by a normal lens, because they tend to be used much closer to the subject.

Canon EF 16-35mm f/2.8L II USM Ultra Wide Angle Zoom Lens

10-20mm F4-5.6 EX DC HSM

Olympus ZUIKO 7-14mm

Nikon 14-24mm AFS f/2.8 G ED

part of camera

Lens - It draws the light into the camera and focuses it on the film plane.

Shutter - It open and closes to control the length of time light strikes the film. There are two types of shutters: a leaf shutter, located between or just behind the lens elements, and a focal plane shutter, located in front of the film plane.

Shutter Release - The button that releases or "trips" the shutter mechanism.
Film Advance Lever or Knob - It transports the film from one frame to the next on the roll of film.

Aperture - It dilates and contracts to control the diameter of the hole that the light passes though, to let in more or less light. It is controlled by the f-stop ring.

Viewfinder - The "window" through which you look to frame your picture. Film Rewind KnobThis knob rewinds the film back into the film cassette.

Camera Body - The casing of the camera which holds the encloses the camera pats.

Flash Shoe - This is the point at which the flash or flash cube is mounted or attached.
Self-Timer - This mechanism trips the shutter after a short delay - usually 7 to 10 seconds - allowing everyone to be in the photograph.