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The effect of the focal length of the lens on the magnification ratio in the conditions of close-up photography or macro photography and photography

We noticed in examples 3 and 4 that the image enlargement ratio increases whenever the focal length of the lens decreases, assuming that the length of the bellows remains the same in both cases (300 mm). When the focal length of the lens was 25 millimeters (in example No. 3), we found that the degree of magnification = 11: 1, and we also saw that when the focal length was increased to 75 millimeters (in example No. 4), the degree of magnification became only 3: 1. There is no doubt that the contemplator In the previous result, he will be shocked when he sees it as a violation of the general rules that we have previously mentioned regarding the usual standard photographs (Nornal Standard Photographs), that is, those images in which the distance of the object from the lens is more than ten times the focal length of the lens, as we have previously mentioned that if the running body Photographing it far from the lens as if it were in infinity, it is better to use lenses with a long focal length or telephoto lenses in order for the image of the object to appear relatively large on the frosted glass Round Class or on the negative image, as we know that if we use a lens with a short focal length or obtuse angle, the The body image appears relatively small on the sensitive plate. However, this rule does not apply in the case of macrophotography (1) or in the case of close up photography. Rather, the opposite becomes true, as the magnification ratio increases with the shortening of the focal length of the lens (Fig. 96), whether the shortening of the focal length is a result of adding Positive lens to the original lens, or was the focal length of the original lens short in nature, as we concluded from the two previous examples No. 3 and 4. (p. 149) Therefore, we find that there is no place for using lenses with a long focal length in photographic transmission conditions when the photographer wants to increase the magnification ratio (i.e., increase the transmission scale). Rather, it is better then to use lenses with a very short focal length (i.e. with an obtuse angle). In view of the optical defects of the additional lenses, special lenses with a very short focal length corrected for shooting at very close distances were made, usually called Micro Lenses or Macro Lenses, through which a high degree of magnification can be obtained to increase the transmission scale (1). The maximum and minimum magnification depend on both the focal length of the lens and the length of the bellows extension. In the following table, we see an example of the effect of these two factors in determining the limits of the magnification ratio. We also conclude from it that the percentage of magnification increases greatly as the focal length of the lens decreases.