المعاصرة ( أو التزامن ) حين التصوير بالضوء الخاطف .. كتاب آلة التصوير

Contemporary (or synchronization) when flash photography Synchronization

(a) Contemporary use of the Diaphragm Shutter:

We knew before in the course of studying the shutter of Aldia, so it takes a certain time to reach its maximum width, then it continues open for a period consistent with the exposure time that we estimate, and then it starts. Shutter lock movement.

If we link the process of opening the shutter with the process of flashing the flash of light, we find that the arrival of the flashlight energy to the top must be contemporaneous with the time in which the shutter is fully open (Fig. possible.

(b) Contemporary when using the focal plane shutter:

Due to the difference in the characteristics of the focal plane shutter from the characteristics of the diaphragm shutter, whereby exposing the entire sensitive plate when using the first shutter takes much more time than the actual exposure speed (1). Therefore, the characteristics of the flashlight suitable for a focal plane shutter must differ from the characteristics of that suitable for a diaphragm shutter. As an explanation for this, we suppose that the exposure time that we estimated when using the focal plane shutter is less than a second, and that the width of the aperture. Between the two curtains is one centimeter, which means that each name of the film takes an equal amount of time! of a second to expose it to light. If the width of the film or the sensitive plate is ten cm, then with the following equation we can estimate the time it takes to expose the entire sensitive plate.

It takes 1/100 of a second to expose each 1 cm of the photosensitive plate
... 10 cm of the sensitive plate takes a time of x seconds

... 10 x 1/100 over 1 = 10/100 = 1/10th of a second

That is, exposing the entire photosensitive plate needs a time of 1/10 of a second if the focal plane shutter is used, but if the user is a digital diaphragm shutter, the entire sensitive film can be exposed in a time of 1/100 of a second only.

From this comparison, it appears to us that the characteristics of the flashlight lamp must differ when using the DIA shutter, so it differs from its characteristics if it is intended for the focal plane shutter. In order for the flashlight lamp to be suitable for the final shutter, the combustion time of the burning material must be long, so that it takes a time equal to the time it takes to expose the entire sensitive film, which is 1/10 of a second. The appropriate characteristics of the flashlight lamp at that time are:

(a) Light of uniform intensity (i.e. it has no peak). The reason is clear in this, as if the flash had a peak, some areas of the sensitive plate would have been exposed to a greater degree than the neighboring ones, and we would not have obtained equal lighting on the whole film. We show in (Fig. 204) an example of the characteristics of a flashlight lamp suitable for a flat focal shutter.

(b) That the ignition of the material takes a long time commensurate with the time it takes to expose the entire sensitive film.