سرعة التعريض Exposure Speed المناسبة لكل من حركة الجسم ،وبعده عن العدسة ،واتجاه حركته

(Explanation of Table 27) The appropriate exposure speed for each of the object’s movement, its distance from the lens, and the direction of its movement.

Exposure Speed ​​is the time period during which the image is recorded (it could be 1/2 of a second, 1/50 of a second, 1/100 of a second, etc.). The speed of exposure must be appropriate to the speed of movement of the body. A fast-moving body requires a large exposure speed, and a slow-moving body requires a slower nursing speed.
Unless you do that, the image will look shaky, Blurred. The speed of exposure is not only related to the speed of movement of the body, but also depends on the following factors:
a- The extent of the distance or proximity between the school and the moving body.
B - direction of movement (vertical, horizontal or similar). C - The focal length of the lens, as the short focal length requires an exposure speed that is less than if the lens had a long focal length.

Notes on this table (No. 27 p. 48):

(1) The nursing speed in this table is estimated by assuming that the moving objects run in a horizontal direction with respect to the camera, that is, the objects move perpendicular to the optical axis of the lens.
(2) The nursing period increases by 1/2 1 times if the body is moving in a diagonal direction with respect to the machine, for example if the exposure speed appropriate for the moving body in a horizontal direction = 1/750 of a second, then the same body requires 1/ 750 x 3/2 = 3/1500 = 1/500 of a second if he were running at the same speed in an oblique direction relative to the camera.

(3) The duration of the exposure increases by 3 times if the body is running in a direction perpendicular to the machine (i.e. if the direction of movement of the body is parallel to the optical axis of the pistol) and if the duration of nursing suitable for the moving body in a horizontal direction relative to the machine = 1/750 of a second, This same moving body requires an exposure of 1/750 x 3 = 1/250 of a second if the body is moving in a direction perpendicular to the machine.

(4) Developing this table assuming that the lens used is of medium focal length. If another long focal length lens or a telephoto lens is used, the exposure speed must increase by an amount equivalent to the power of the telephoto lens. For example: if the exposure speed is 1 1/100 of a second If the lens is of medium focal length, the appropriate exposure when using a 2x telephoto lens should be 1/200 of a second.

(Table 28)

Very accurate (not shaky)? ,

Example: A bicycle is running in a race, and the direction of its movement is oblique with respect to the camera and it is 10 meters away from it. What is the appropriate exposure speed to record very accurate images (not shaky)?

Answer: From Table No. 28, we conclude that the movement speed = approximately 50 kilometers per hour, and from Table No. 27, we deduce that the exposure speed = 1/1500 of a second if the bike were running in a horizontal direction relative to the machine.
As for what was mentioned above that the bicycle runs in an oblique direction, therefore, according to Note No. 2 on page 46, this speed must be multiplied by 2/3, meaning that the exposure speed = 1/1500 x 3/2 = 3/3000 = 1/ 1000 of a second.