الإضاءة بالفلاش .. اختيار واستخدام المواد .. كتاب التصوير الضوئي

Flash Lighting .. Choosing and Using Materials .. Book of Photography

Choosing and Using Materials
Flash Lighting

All modern photographic equipment can be used with flash, of which there are various types. Flashes and cubes now have a blue cover, which allows them to be used in color with daylight film.

- Flashes (burning):

Large-scale machines use a cube, which is four small flashes mounted on a single rotating base and connected to the top of the machine.

After each flash shot, the cube rotates 900 degrees and a new light appears in front of the subject. Some cubes operate on batteries, while others operate automatically and do not require a battery. You must choose the model of cube that suits the technique. If the opening of the screen wall is not changeable, we can only use the cube for a very limited area, usually between 1.80 and 3 meters.

As for the independent flashes, they are available in different sizes. The smallest ones without a bottom are the most common and the least expensive. Large bulbs (about the size of a household light bulb) give an enormous amount of light and are used by professionals. Some bulbs are also slow-burning, which allows them to be used with a curtained shutter at all speeds: they are on the way to extinction. The flash bulbs are placed in a box with a reflector and a battery is necessary to ensure their ignition. There are now bulbs mounted side by side on either end of a plate with small reflectors. This method allows pictures to be taken in sequence, i.e. without having to change the bulb after each shot.

All incandescent lamps are built on the same principle: a glass case protected from explosion by a plastic jacket containing a wire covered with an explosive paste and a coil of combustible wire of magnesium, aluminium or zirconium in an oxygen atmosphere. When the current passes through the wire, the explosive paste causes the metal to burn instantly.

- Electronic flash:

The flash time of the electronic flash is very short and therefore there is no risk of the image being moved, whether by the photographer or by the moving subject, provided that the level of surrounding light is weak. Small flashes are attached directly to the machine on the nail carrying the extra parts, while large flashes are mounted on the case by a small elongated alloy. The matching of the flash ignition time with the time of taking the picture is achieved either by a small rope or by the nail carrying the extra parts if it is a timer.

- Flash and shutter synchronization:

The simplest machines are synchronized with flash lamps and cubes for an instantaneous speed close to 1/30 second. The more perfect machines can be synchronized with the flash lamp (M or FP) and with the electronic flash (X-timer). It is very important to set the flash on the appropriate timing contact because the different types of flash do not reach their maximum luminous output with the same delay. The flash lamps are noticeably delayed, while the electronic flash reaches its maximum luminous output immediately. By declaring the correct speed you are at the same time ensuring that the shutter will be at its maximum aperture at the time the flash is emitted: if this condition is not respected there will be no picture or the picture will be incomplete (burning shutter). Look at the drawing: if you use the M calibre with a flash lamp the shutter will be at its maximum aperture when the flash is emitted. If you use the same M calibre with an electronic flash the flash will be emitted before the shutter has time to open. Conversely, in X-synchronization, the flash will be fired after the shutter is activated, while the electronic flash will reach its maximum at the time specified for the maximum shutter opening.

- Electronic flash: The small models are one-piece and are powered by batteries. The synchronization with the shutter is ensured by the nail holding the timer parts in the box or by a small synchronization cord. On the back there is a battery indicator and a calculation dial.

The flashes with greater power (reportage) are usually made up of two parts, on the one hand the torch which can be fixed to the machine by a metal alloy and on the other hand the power which is carried on the shoulder.

- This box allows the simultaneous ignition of a large number of flashlights. It is powered by a set of batteries.

- Flashlights: There are different shapes and sizes of boxes and reflectors. Some are foldable and the battery is often placed inside the box. There are small and large flashlights, the choice of which depends on the amount of light needed to illuminate the subject. The powerful flashlights have a truncated bottom, while the small ones are bottomless. The desk flash has four bulbs, each with its own reflector.