# The size of the matrix does matter.

One of the most important and basic parameters of any photographic equipment is the size of the photosensitive sensor of the camera. And this is not about megapixels, but about the real physical area of the photosensitive element.

Previously, most photographers were shooting on film cameras, which used the so-called 35mm film (standard film from the distant 1930s). These were quite old times, and somewhere since 2000, digital mirror cameras (CCP) became very popular, the principle of operation of which remained the same as in film cameras, but instead of CCP film they began to use an electronic photosensitive matrix, which forms the image .

That’s just the price for the manufacture of such a matrix is hundreds of times more expensive than a conventional film. Due to the huge price for the manufacture of an analogue of 35mm film and the overall complexity of manufacturing a huge matrix with millions of transistors, a number of manufacturers began to produce cameras with a sprinkled matrix. The concept of ‘sprinkled matrix’ means that it is a smaller matrix for a standard 35mm film size.

Crop factor (Crop – from English “cut”) is an indicator for sprinkled matrices, it measures the ratios of the diagonal of a standard frame of 35mm film to the diagonal of the spritted matrix. The most popular cropping factors among CPC are K = 1.3, 1.5, 1.6, 2.0. For example, K = 1.6 means that the diagonal of the camera matrix is 1.6 times less for the diagonal of a full-frame matrix or for a diagonal of 35mm film.

In fact, not all CCPs are equipped with a sprinkled matrix, now there are a lot of cameras that have a matrix size equal to the size of the 35mm film, and K = 1.0. Cameras that have a matrix-sized 35mm classic film are called full-frame digital mirror cameras.

Breezy cameras are usually APS-C cameras with K = 1.5-1.6, or APS-H cameras with K = 1.3. Full-frame cameras are usually called Full Frame. For example, Nikon APS-C cropped cameras are called Nikon DX, and full frame cameras are called Nikon FX.

DX (spud camera, APS-C type, K = 1.5) has a matrix with dimensions of approximately 23.6 by 15.8 mm, the area of such a matrix will be 372.88 sq. M.

The FX (full-frame camera, K = 1.0) has a matrix with dimensions of approximately 36 by 23.9 mm, the area of such a matrix will be 860.4 square meters

Now we divide the areas of the matrices and obtain that the DX matrix is 2.25 times smaller than the full-frame matrix. To quickly calculate the real difference in the physical size of a full-frame and sprinkled camera, it is enough to square the spacing factor. So, DX cameras use the krop factor K = 1.5, we find that the areas of the DX and FX cameras differ by 1.5 * 1.5 = 2.25 times.

If we install a standard (for an example) lens with a focal length of 50mm on a cropped camera and look through the viewfinder, we will see that the viewing angle has become narrower than with the same lens on a full-frame camera. Do not worry, everything is in order with the lens, simply because the matrix of the sprinkled camera is smaller, it “cuts out” only the central area of the frame, as shown in the example below.

The difference between a cropped and full-frame camera. The first picture was taken on a full-frame camera and a 50mm lens, the second picture was taken on a sprinkled camera and the same lens. The viewing angle on the sprinkled camera has become smaller.

At the same time, many people have the impression that the focal length of the lens is changing – but this is just an illusion. In fact, the viewing angle that a person observes in the viewfinder changes, the focal length of the lens does not change. The focal length is the physical size of the lens and it will remain the same on any camera. But because of such an illusion, it is convenient to say that the visible picture on a sprinkled camera is similar to a 75mm lens (50mm * 1.5 = 75mm) when used on a full-frame matrix. That is, if you take two tripods and two cameras – one full-frame, the other is cropped and screw the lens to the full-frame with a focal length of 75mm, and the lens with a focal length of 50mm – then eventually we will see an identical picture, because the viewing angles from them will be the same.

The recalculated focal length is called Equivalent Focal Distance, abbreviated EGF. EGF is recalculated even for cropped lenses such as the Nikon DX and Canon EF-S.

And an example of the same image taken from the same distance, without changing the settings, but only in the cropped mode:

Crop

Snapshot on full-frame camera in DX mode. Visible difference in viewing angle. DX mode, or DX camera as if cutting from the original image, which gives the lens, only the central region.

In fact, when using lenses from Full frame cameras on sprinkled cameras, we get some significant advantages:

The viewing angle decreases, making a telephoto from a standard lens, and a super telephoto from a telephoto.