تعريض الفيلم .. كتاب التصوير علم وفن

Chapter Three Exposing the movie

By that, we mean introducing the exact amount of light into the camera to fall on the film, giving us a negative with an exact density and gradient shades of gray, or colors that align with the natural colors of the subject.

Basically, the weaker the prevailing light, the slower the sensitivity of the film

The higher the exposure

How to determine the exact exposure: 1 - This can be determined using the exposure tables found in the instruction sheet attached to each film, and they are correct for photographing ordinary subjects.

Under normal and specific lighting conditions. The exposure scale can be used in all of the above-mentioned types. 3- As for guessing the exposure, it generally leads to failure, because the human eye adapts quickly and automatically to minor changes in the intensity of lighting. The eye does not perceive such minor differences, but the film, especially the color film, responds strongly and immediately to such changes. Therefore, we find that the negative and the image has become more or less exposed than required. .

We will come back to that after explaining how exposure is:
How to regulate exposure:

The exposure is done by two things, each of which performs two functions: 1- The pupillary aperture: this regulates: a- The size of the light falling on the film. B - the depth of the acute area (depth of field).

2- Shutter speed: This regulates: a- The time taken for exposure to light.

b - Image sharpness for moving objects.

We can liken the pupil aperture to the opening of a water tap and the shutter speed to the time it takes for the tap to fill a cup of water (the amount of light needed for a good exposure). A short time (fast shutter speed) or open a small aperture (narrow pupillary aperture)

And then we will need a long time (slow shutter speed) to fill the glass (the same amount of light). It is noted that the pupillary aperture passes twice the amount of light that the aperture passes

previous to it:

As well as shutter speeds, each speed is twice the speed of the previous one, thus passing half the amount of light for the previous speed.

We notice that the amount of light entering the film is the same in the three cases, and we find that beginners always use a speed such as 1/125 to prevent camera shake during exposure, and choose the appropriate aperture for the prevailing light according to the exposure scale. As for the experienced photographer, he knows that he has many options. Aperture 16, for example, gives it a large depth of field, but it may need to stabilize the camera to prevent vibration, and aperture 4 gives it a shallow depth of field, but the high spe it to stabilize and freeze movement. In all cases, the amount of light falling on the film is the same in terms of illumination.
Translate colors or shadows.