The word “macro photography” usually means photographs taken on a sufficiently large, but still not microscopic scale, i.e. from about 1:10 to 1: 1. Pictures with a scale exceeding 1: 1 are already referred to as microphotographs, and everything smaller than 1:10 is considered just a close-up. The given ranges of scales are very arbitrary, and can serve only as guidelines, and not in any way rigid boundaries between individual genres of photography.
Perhaps the reader does not quite own the concept of scale, and the numbers 1: 1 tell him little about what? There is nothing complicated here. The shooting scale is the ratio of the linear dimensions of the subject to the linear dimensions of its image projected by the lens onto the matrix or film. A 1: 1 scale means full-size shooting, i.e. an object with a size of 10 mm will correspond to an image with a size of 10 mm. A scale of 1: 2 means half the actual size, i.e. the projection of a ten-millimeter object will have a size of 5 mm. If the first digit is larger than the second, then this tells us about the possibility of shooting with an increase. For example, at a 2: 1 scale, an object 10 mm in size will be enlarged to 20 mm. Let me remind you that we are talking about the size of the image projected onto the matrix of the camera. Of course, when viewing photos on a computer monitor or when printing, macro objects will look much larger than they really are.
The technical characteristics of any photographic lens always indicate the maximum shooting scale achievable with the minimum focusing distance for a given lens.
Sometimes, instead of the maximum scale, the so-called lens zoom ratio. For example, a 1 × magnification factor corresponds to a 1: 1 scale, 0.5 × corresponds to 1: 2, and 2 × indicates the possibility of shooting at a 2: 1 scale, i.e. twice the actual size.
Macro lens selection
For amateur macro photography, the presence of a specialized macro lens, although desirable, is still not critical. The standard whale zoom, which amateur cameras are usually equipped with, allows you to achieve a scale of approximately 1: 3 in the telephoto position, and this is quite enough for shooting flowers, butterflies and the like.
However, if you decide to take macro photography seriously, you will most likely need a real macro lens that allows you to shoot on a 1: 1 scale. Nikon calls its macro lenses micro lenses, but this does not change the essence. It is the ability to shoot on a 1: 1 scale (or even larger) that distinguishes a full-fledged macro lens from just a lens with “close focusing ability” or some kind of “macro mode”.
However, even real macro lenses are far from always suitable for serious macro photography, and therefore we should dwell in more detail on some parameters that distinguish different macro lenses from each other.
Focal length is perhaps the most important parameter to consider when choosing a macro lens. In general terms, the larger the focal length, the better. The reason is that the working distance in macro photography directly depends on the focal length of the lens. The working distance is the distance from the front edge of the lens barrel to the subject you are shooting (not to be confused with the focusing distance, which is measured from the camera’s matrix). When shooting at the same scale, a lens with a larger focal length will provide a greater working distance than a lens with a smaller focal length, and the larger the working distance, the more convenient it is for the photographer to work.
The main disadvantage of short macro lenses (like AF-S DX Micro-NIKKOR 40mm f / 2.8G, AF-S Micro NIKKOR 60mm f / 2.8G ED, Canon EF-S 35mm f / 2.8 Macro IS STM, Canon EF 50mm f / 2.5 Compact Macro) is that in order to achieve maximum scale, you have to get close to the subject, so that it is separated by a few centimeters from the lens. This creates a number of problems:
If the object of the shooting is an insect or other small animal, then getting too close to it, you risk scaring it off. By the way, this is why experienced macro photographers prefer to hunt insects at dawn, while they are inactive.
The closer you are to the subject, the higher the probability of blocking the natural light, and for the correct use of flashes or reflectors, you will not have enough space.
A short macro lens, having an image angle too large, captures a lot of extra background elements in the frame and, thus, makes visual isolation of the main object more difficult.
Objects taken point blank acquire an unnatural perspective. This, by the way, is a characteristic feature of most macro shots made using compact soap dishes.
That is why macro lenses with a focal length in the region of 50-60 mm (or equivalent) are unsuitable for serious macro photography, despite its ability to shoot on a 1: 1 scale.