One of the most important and basic parameters of any photographic equipment is value of the photosensitive camera sensor. And this is not about about megapixels, but about the real physical area of the photosensitive element.
Previously, most photographers shot on film cameras that used the so-called 35mm film (film standard from the distant 1930s). Those were quite old times, and somewhere since 2000, digital-SLR cameras (DSC) became very popular, the principle of operation of which remained the same as in film cameras, but instead of the DSC film, they began to use an electronic photosensitive matrix, which forms the image ...
That's just the price of making such a matrix hundreds of times more expensive than ordinary film. Due to the huge price of manufacturing an analogue of 35mm film and the general complexity of manufacturing a huge matrix with millions of transistors, a number of manufacturers began to produce sprinkled cameras... Concept 'cropped matrix 'meansthat we are talking about a smaller matrix for a standard size of 35mm film.
Crop factor (Crop - from English "cut") Is an indicator for cropped matrices, it measures the ratio of the diagonal of a standard 35mm film frame to the diagonal of the cropped matrix. The most popular crop factors among CPCs are K = 1.3, 1.5, 1.6, 2.0. For example, K = 1.6 means that the diagonal of the camera sensor is 1.6 times smaller for the diagonal of a full-frame sensor or for a 35mm film diagonal.
In fact, not all central control centers are equipped with a cropped matrix, now there are a lot of cameras in which the matrix size is equal to the size of a 35 mm film, and K = 1.0. Cameras in which there is a matrix the size of a classic 35mm film, are called full-frame digital SLR cameras.
Cropped cameras are usually APS-C cameras with K = 1.5-1.6, or APS-H cameras with K = 1.3. Full-frame cameras are commonly called Full Frame. For example, Nikon's cropped APS-C cameras are called Nikon DX, while full-frame cameras are called Nikon FX.
DX (cropped camera, APS-C type, K = 1.5) has a matrix with dimensions of approximately 23.6 to 15.8 mm, the area of such a matrix is equal to 372,88 sq. Mm.
FX (full-frame camera, K = 1.0) has a matrix with dimensions of approximately 36 to 23.9 mm, the area of such a matrix is equal to 860,4 sq. Mm
Now we divide the area of the matrices and we find that the DX matrix is smaller than the full-frame matrix in 2,25 times. To quickly calculate the real difference in the physical dimensions of a full-frame and a cropped camera, it is enough to square the crop factor. So, DX cameras use crop factor K = 1.5, we get that the areas of DX and FX cameras differ by 1.5 * 1.5 = 2.25 times.
If we install a standard (for example) lens with a focal length of 50mm per cropped camera and look into the viewfinder, we will see that the viewing angle is 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 cropped camera is smaller, it “cuts out” only the central region of the frame, as shown in the example below.
At the same time, many people have the opinion that the focal length of the lens is changing - but this is just an illusion. In fact, the angle of view that a person observes in the viewfinder is changing, the focal length of the lens does not change. Focal length is the physical size of the lens and will remain the same on any camera. But because of this illusion, it is convenient to say that on a cropped camera, the visible picture is similar to a 75mm lens (50mm * 1,5 = 75mm) when used on a full-frame sensor. That is, if we take two tripods and two cameras - one full-frame, the other cropped and screw a lens with a focal length of 75mm on a full-frame one, and on a cropped one with a focal length of 50mm - then in the end we will see an identical picture, since they have will be the same.
And an example of the same picture taken from the same distance, without changing the settings, but only in cropped mode:
In fact, when using lenses from Full frame cameras on cropped cameras, we get some significant advantages:
- Reduced viewing anglemaking a telephoto from a standard lens, and a super telephoto from a telephoto. So using a 300mm telephoto, we get a viewing angle the same as in a 450mm lens on a 35mm film. This is a pretty great opportunity to buy a cheap zoom telephoto for less money and due to the crop factor, get a large EGF.
- Due to the fact that full-frame lenses work only in the central area on cropped cameras, you can get rid of such image defects like vignetting, a drop in resolution at the edges of the frame, part of the distortion. Usually in the central region of the frame, image quality is maximum.
Also, using lenses from cropped matrices, we get lenses cheaper. Although there are downsides. Lenses from cropped cameras need to cover a smaller area of the photosensitive element, which means you can use less expensive glass, make less weight, etc. At the same time, when buying lenses for cropped matrices and with the subsequent transition to full frame, you will have to additionally buy new lenses for a full frame. I advise you to read the related article - Nikon lens differences, and - Features of cropped cameras and lenses
Cropped cameras (cropped matrices) are simply smaller matrices, and in order to understand the amount of matrix reduction, the concept of crop factor is used. The crop factor is convenient to use to obtain EGF lenses when using them on cropped cameras. To obtain EGF of any lens, when using it on a cropped camera, it is enough to multiply the value of the focal length of this lens by the crop factor of the camera.
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