مقياس النقل .. كتاب آلة التصوير

Transfer scale

As a result of the object approaching the lens, the relative area occupied by its image on the sensitive plate, film, or frosted glass increases. The ratio between the length of the image and the length of the object is expressed as the Reproduction scale or the Magnification ratio. If the length of the body in nature is -90 cm, and the length of its form = 9 cm, then the measure of transmission is then 9/90, i.e. 1/10. If the length of the image is equal to the length of the object, then the transmission scale becomes 1:1.

All English and American references have used the two words (Image Size, i.e. the size of the image), and (Object Site, i.e. the size of the body, as a basis for estimating the measure of transmission, but these two words lack complete accuracy, because if it is permissible to say the size of the body »Weiss, it is permissible to say (image size) The word size means that the body has three dimensions (length, width, and depth).

And just as the expression with the word (volume) is not an accurate expression, it is also not right to replace it with the word (size with the word area), so if the length of the surface is 50 cm, its width is 30 cm, the length of its image is 5 cm and its width is 3 cm, then the surface area = 1500 cm and the area of ​​its image is 15 poison . It is wrong to say that the transmission scale in this case = 15:1500, as it is in fact equal to either of the two ratios 5/50 or 3/30, i.e. 1/10 in both cases. Hence it is considered in the rule of the correct naming to say that

Transmission scale = width of the image over the width of the object or the length of the image over the length of the object

It is also considered a correct expression to say that the transmission measure =
The chord of the image on the chord of the body (Fig. 94).

Therefore, in order to prevent confusion, we see that we agree on the following formula that we will follow in this book, which is! Transmission scale = image length along the body.

It also expresses the ratio of the length of the image to the length of the body
It is = Magnification and is symbolized by the symbol (T).

And given that in all cases of standard, usual images, the ratio between the length of the image to the length of the body is less than one whole, so carefulness in the expression necessitated that we call it the ratio of reduction, not the ratio of enlargement, provided that it is limited to
The last designation only refers to the case where the image length is greater than the object length (ie if the object is located at a distance from the lens less than twice its focal length).

However, it is customary for the expression (the zoom ratio) to be applied to the ratio between the length of the image to the length of the body, whether the length of the image is greater or less than the length of the body. Even assuming that the length of the image is smaller than the length of the body, the expression of this relationship as (the ratio of zoom) is still a correct expression as well, since the magnification at that time is less than one correct, and therefore we will proceed to use the word “zoom” in either of the two cases and to estimate the degree of Reduction is mathematically defined as 1 magnification / magnification.