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How is exposure determined for flash?

Exposures with flash bulbs must be calculated using a pilot numbering system and based on the film speed used a pilot number is given for each individual flash. This number is divided by the distance from the flash to the object to be photographed, and the resulting result represents the practical aperture that the lens must be set to (Fig. 37).

Most flashes and many simple cameras contain a calculator (Fig. 38) to convert pilot numbers directly into common values ​​made up of

Distance value and aperture value

What are the focal plane flash bulbs?

An ordinary flash bulb lights up and fades quickly in less time than it takes the closed shutter in the focal plane to pass through the film. Thus, at relatively high shutter speeds, only a portion of the image frame will be exposed. Lamps in the focal plane (FP) burn more slowly so that their output remains reasonably even over the entire time the shutter is open. Thus (with the correct synchronization contacts) the lamps can be used in any

A - The correct exposure for a normal flash is related to the distance that extends from the flash to the subject to be photographed and the aperture used. B - The correct aperture is determined by dividing the guide number of the film by the distance extending from the flash to the subject to be photographed.

shutter speed, but the greater the speed, the smaller the guide number to be used. FP bulbs are hard to come

Dial included to calculate flash exposure.

What is electronic flash?

The electronic flash contains a complex set of electrical circuits, and it is often considered heavy when compared to the bulb device. In any case, its operating costs are considered insignificant (mostly the number of flashes ranges from 50-200 flashes per set of low-voltage batteries) and it is in fact instantaneous. It only takes a very short period of time. These last two factors in particular make electronic flash ideal for synchronization at high shutter speeds and for freezing the effect of moving objects (Fig. 39).

Some electronic flash guns contain a sensitive device
You turn off

Adjust the position of the shutter speed button for the electronic flash

The flash automatically when a sufficient amount of light reaches the subject to be photographed by measuring the light reflected from the photographed subject until a certain limit is reached. Non-automatic flash guns are used with a system of guide numbers

Some electronic flashguns include an output of a flash bulb without the need to use bulky, expensive kits. However, with modern high-speed films using large apertures, this is rarely considered a disadvantage, and in fact there is a growing trend towards the use of electronic flashguns. Especially in non-reflexive cameras.

Why are most flash bulbs painted blue?

At a certain time, flash bulbs appeared in three different colors - transparent, blue and yellow - and transparent flash bulbs used white film with
With black and blue flash bulbs have been used with color films to equalize daylight, and yellow bulbs are for color films to balance with studio light or artificial light. In fact, it was possible to buy liquids to paint the transparent bulbs in the colored works. The interruption of demand soon led to the cessation of the yellow bulbs, and most people prefer to use films in daylight for all their work, either with blue flash bulbs or with a blue filter for indoor use.

The demand for transparent bulbs. It quickly decreased due to the increasing popularity of color films and due to the fact that blue lamps can be used with black and white films. Blue flash lamps send light almost equal in color temperature to normal daylight. Ideal for color slide films used in daylight, they can also be used indoors with color negatives or any slight imbalances can be corrected at the printing stage.