حساب التكبير .. كتاب آلة التصوير

Zoom calculation

In addition to the possibility of calculating the magnification (T) from the ratio between the length of the image and the length of the body, it is also possible to calculate it
(or calculating the transmission scale) by the factors that affect the length of the image, that is, the zoom ratio. These factors are:

(a) The focal length of the lens (p), so the magnification increases with the shortening of the focal length of the lens.

(B) The length of the bellows extension, i.e. the distance between the image and the lens (P). The magnification increases as the length of the bellows extends.

(C) The distance between the lens and the object (Q), so the magnification increases whenever the distance of the object from the lens decreases.

Based on these factors, the “magnification” can be calculated in one of the ways that we explain, as follows:

(a) If we know both: the distance of the object from the lens, and the distance of the image from it (from the following equation No. 1, page 145).

(b) If we know both the distance of the image from the lens and the focal length (from the following equation No. 3, page 146).

(c) If we know both: the distance of the object from the lens, and the focal length (from the following equation No. 6, page 148).