Crop factor. What is it and how important it is when choosing a digital camera.

Crop factor is the term that added to the vocabulary of photographic terms the emergence and widespread use of new generation cameras. With the development of modern innovative technologies, more and more SLR digital cameras began to appear on the market with the cost affordable for non-professionals. Such buyers, except for the price, can only distinguish one more category by which they choose the camera - this is the number of megapixels. With megapixels, they have already sorted out something and, vaguely imagining what it really is, still understand that the more of them, the better the device. However, as it turned out, another important characteristic that distinguishes the quality of digital cameras among themselves is the crop factor. Before you buy a camera, it's worthwhile to figure out what it is.

Few amateurs at least once asked themselves the question, why, if the lens and lenses have a circular shape, the frame while they remove the rectangular? There is nothing difficult in answering this question. Projecting a photographed image onto a carrier in a camera, the lens optics simply cut off the "extra" part of the image, giving it a rectangular shape. This is very convenient for the production of photographic film, consisting of a series of rectangular frames, and for making photographs, giving both compactness and versatility.

Due to the long use of film photography, the frame size on the film continues to be used as the reference size. Nobody even thinks of changing it even now, when shooting on film is almost a thing of the past. In our time, with the accession of digital photography, shooting is carried out on a special matrix, which can be conditionally compared with the film.

Matrix, which corresponds to the size of a film frame, is usually called full-format. However, most digital SLR cameras have matrices with a size much smaller. Naturally, on such matrices only the central region of the image is imprinted, which could get on the full-format matrix. Visually it looks as if the frame is photographed with an objective lens that has a much larger focal length.

Hence, a term has arisen that determines the "increase" of the focal length, which in fact does not occur, because here, as in our example with round optics, the outer part of the frame is simply cut off. In English, the word "crop" (krop) is translated as "cut off". Hence the name of the term - the croping factor, which denotes such an artificially increased focal length. This accurately describes at the same time how the shooting process actually takes place, because in the physical sense the focal length of the photo lens has not changed, but only the angle of view has changed.

So, the frame size of a 35-mm film of 24x36 mm was and remains the reference one, with which the crop factor is now connected. For this frame, it equals 1. At the very beginning of the digital photography era, Nikon wisely decided that it was possible to produce digital SLR cameras with the ability to use old optics with them, which was manufactured for decades and often cost more than the cameras themselves.

However, with the implementation of this idea, problems arose. It was too expensive to create a full-format sensor, and in very small sense it did not make sense.

As a result of the research, a sensor was created, which was one and half times smaller than the frame of the 35-millimeter film diagonally. Thus, for such a sensor, 1.5 is its croping factor. Canon, by the way, later found an even more optimal solution. The croping factor of his cells became 1.6.

To somehow distinguish it, Nikon began to call its croping factor DX, and the full-size FX sensor. This encoding continues to exist now. It is used by many other companies, except for Nikon.

Manufacturers of cameras with a crop factor used the fact that the area of their sensors decreased by more than half. This allowed us to save on the manufacture of powerful and expensive optics. Manufacturers began to produce in digital quantities digital cameras available to the widest circle of amateur photographers.