الفترة الزمنية الفاصلة بين كل صورة والتالية لها حين التصويرالسينمائي على فترات متقطعة

- (Explanation of Tables No. 37 - Part One and Two) (and No. 38 - Part One and Two)

The time interval between each image and the next while intermittent cinematography
Time-Lapse-Cinematography

Intermittent cinematography is the means by which the long period that a certain movement takes in nature can be compressed to appear on the screen into a shorter period that may take seconds or minutes.

And this process depends on what we know that if the camera has 24 images per second, and the projector runs at the same speed, then the apparent speed of movement of the objects on the screen must be equal to their movement in nature. But if the number of images recorded by the camera per second is less than 24 images per second, while the projector speed remains at 24 images per second, then there is no doubt that the apparent movement on the screen will appear faster than it does in nature. The rate of apparent movement speed on the screen increases whenever the number of images recorded by the camera per second decreases.

Thus, it was found that it is possible to compress the time of movements that take long periods of time in nature (may be days) to appear on the screen in a few seconds or minutes, if one image is recorded every specified period of time (may be seconds or minutes). The time pressure rate depends on the following factors:

(a) The period it takes for movement in nature (estimated in hours or days).
(b) Projection duration in which we ask to watch the film representing the compressed movement.
(C) The speed of the projector (estimated by the number of images per second). We have assumed in the following tables No. 37 and 38 that the projector will run at a speed of 24 images per second).

The table (No. 37, part one and two) differs from table (No. 38 - part one and two) in that the first table, No. 37, in its two parts, is concerned with cases in which the duration of the show is estimated in “minutes.” As for the second table, No. 38, with its two parts, it is concerned with cases that The duration of the presentation shall be in “seconds”.

Example: It was decided to photograph the growth of a seed of a certain plant placed in a glass container, and it takes 3 days for it to grow in nature until it becomes a plant. We want to see on the monitor screen the movement of growth, so that this snapshot takes only fifteen seconds (when the projector runs at a speed of 74 images per second), so what should be the time period that separates each image from the next when shooting? .

Answer: From the table (No. 38, Part 1, pg. 77), we find that it is obligatory to record one image every 12 minutes.

Note: Kindly, Mr. Mohamed Ibrahim Adel Al-Maeed at the Higher Institute of Cinema calculated and prepared all the data contained in these four tables, and the parts of the second were rounded to one decimal number.