اختلال شكل الأجسام السريعة الحركة عند استخدام غالق المسطح البؤري لتصويرها .

Distortion of fast moving objects when using the focal plane shutter to photograph them:

The previous comparison is of great importance from a practical point of view when photographing with a shutter of this type, as the full exposure of the entire sensitive film took a time equivalent to about ten times the speed needed to freeze movement. In fact, each region took a period of time to be exposed, which is PIP to freeze the movement and not to produce a shaky image, but if we imagine that the body was moving very quickly and at a close distance, such as a car in a race, for example, then there is no doubt that the period that passes between exposing the first region (i.e. one side of the film) ).

Distortion of fast moving objects if shooting with a focal plane shutter:

Replace the direction of the arrow in the picture with the direction of the movement of the two curtains - and the dotted lines symbolize the shutter aperture - and it is noted that the fast movement of the cart is moving from left to right. Thus, the movement direction of the vehicle image on the frosted glass in the camera is opposite to the movement of the vehicle, i.e. from right to left. Case A: the shutter moves in a horizontal movement from left to right, i.e. against the movement direction of the body image, so the length of the vehicle in the image decreases and the round wheels take an oval shape And its length becomes greater than its width.
Case B: In which the metacarpal moves horizontally in the same direction as the movement of the body image, so the image of the chariot appears longer than the reality, and its round magazines take an oval shape, its width is more than a circumference.
Case C: The suspended moves from top to bottom, so the height of its body image increases, in addition to the appearance of wheels in an oval shape inclined in the direction of the movement of the body image.

The end of exposing the other side (i.e. the last region of the film) will be about a second, or about - a second, which is considered a large period for a fast-moving object. This will result in an imbalance in the measurements and shape of the body. Here we repeat that this imbalance did not result from a decrease in the speed of exposure to light, which is a fraction of a second. Rather, it resulted from the passage of a period of time estimated at about a billionth of a second between exposing one end of the film and exposing the other end, and the body had moved in it (Fig. 65).