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Aperture is an exposure meter

One of the most important controls in any camera is the lens aperture, and it is worth here to take full advantage of the possibility of the camera discovering how the aperture works As well as mentioning the designations of copier models that are characterized by complexity. And enable cameras that enjoy automatic exposure these days to disregard their technical qualities, however, good pictures are taken, and despite that, the numbers remain, and to benefit greatly from the camera, it is enough for one to be able to understand what these numbers mean.

What do the numbers mean? It appears that the lens numbers are the most tyrannical numbers of them all. They fall around the lens barrel, such as No. 2, 2, 80, 5,604, 80, 110, 16, etc... At first glance, they seem illogical, meaning that there is no need for them - they are not clearly sequenced. Because it involves Western numbers such as 208 and 5.6. However, there is a reasonable reason for choosing it, and the most important thing is that it is a distinctive set of numbers. So, a photographer who chooses a new camera or lens can recognize what it is, which reduces the risk of confusing it with an anisotrometer, for example, a lens. Most of the lenses that are used in photography have a variable aperture that is controlled by the iris membrane, which has become a symbol of photography, and the numbers show the numbers - - the diameter of the aperture, indicating the aperture of the lens in various joyful situations. For example, by just a few millimeters, so that the small aperture of light to enter the film is enlarged, compared to the scale of the F-numbers, which fall in an inverse way, confusing or confusing »at 3 mm, and the large aperture may be 25 mm - the scale is larger The problem is that we are not very concerned The amount of light that passes through the lens as the actual brilliance of the image because it depends not only on the scale of the aperture through which the light passes but on the focal length
For the lens that is also used, and the focal length of the lens, which is generally the distance from the lens to the film, gives an indication to the photographer about measuring the image of the target that will appear on the film. Conversely, a short focal length lens is born, which is a wide angle lens. The focal length of the lens is engraved in millimeters on the front barrel, which indicates the distance that the lens glass must focus on away from the film to form an image of remote targets. For this reason, the close-up lens is longer than standard lenses, so the lens elements must be moved away from the film, and since the image The image formed by the long-dispersion lens is larger than the image formed by the standard lens, so the light emitted from a part of the subject spreads over a wide area when using a lens.
Long and second contrast, and therefore very existing, which means that if the two lenses have an aperture of equal width, then the long contrast lens forms a larger image, but it is less brilliant.

Calculating the numbers Photographers, because of the above, use an f-number scale, because it takes into account the focal length so that the brilliance of the image of any subject is the same at any specific f-number, just its focal length divided by its aperture, for example, the f-number is A lens whose focal length is only 50 mm with an aperture of 25 mm is the F-Number and it says: F2 and you only have to move the iris cap until it reduces the aperture to about 16 F and when you use the lens, the scale that works to help judge changes by a factor From two - that is, by doubling or splitting the brilliance of the image into two halves, and this aperture to 1205 mm. The lens works with an aperture of F4 and also stops it on the number 3 to get
It means doubling the pure field of the lens into two halves, and because the distance changes with the squared diameter of the lens, the F-numbers are the square roots of the numbers in the two doubled lists. Take the numbers 201 08040 16 320 and 64 and calculate their square roots to get 10000. ... 2,8280 20 1,414 5,657 11,314080 and 16
These numbers have been rounded to give a common sequence, except to say so strictly that 5.657 is closer to 5.7 than to 5.6. The series then implies a logical understanding - every position or calibration of the previous position or calibration is cut into two halves, and it is a pity that the series is inscribed in reverse . And it has a great value that is divided into its area or its spaciousness, and its numbers appear to be tyrannical, but they are universal and distinctive.
1) Adjusting the aperture The iris membrane works on the first membrane showing the lens with its wide aperture of about 12.8, but by reducing the aperture. Reducing the effective aperture narrows the conical-path of light, and when the lens has an aperture of f/16, it forms a very straight image.

2) Adjusting the exposure Opening (or widening the film) doubles the aperture area by one stop and allows a double amount of light to reach the film, and the published image shows the effect of this on the exposure.