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What is the purpose of the depth of field preview button?

Depressing this button (or switch) locks any auto diaphragm lens to its pre-selected aperture. This displays the depth of field on the viewing screen and, while this is not entirely representative of the final image, gives a good impression of the expected sharpness and blur. Of course The screen becomes dark at the same time and it is difficult to see the image in very small apertures.

What is the wide angle lens?

The wide angle lens is . A lens that includes specifications that are much larger than what is included in the standard lens (Fig. 25), as it has a shorter focal length, and a 28 or 35 mm lens is often chosen for the 35 mm camera, but lenses with a much wider angle are available, and we find that the widest measurement is 13 mm. The wide-angle lens has many characteristics in the image and each part is recorded in a smaller size, and this has two effects: it emphasizes the front of the image and requires a tight viewpoint if any part of the image is to be large, and this point of view, with uh the large depth of field available, can give an impression Unusual depth in the picture The high perspective drawing often looks distorted, especially in the picture of the masses of people.

What is a long focal length lens?

Captures distant details while enlarging them to the size of the full image area Figure (27) A lens whose focal length is twice the normal focal length is very useful when taking head and shoulder portraits and for capturing fine details of landscapes.

Many 110mm cameras have a lens of this type at the flick of a switch, and the 110mm is a popular choice for 35mm interchangeable-lens cameras. The reduced depth of field makes it very easy to throw a stunning background or ground out of focus. Users of a 35 mm 676 cm SLR camera can choose from a wide range of lenses, mirrorless or all-glass combination, to extend photographs out to a great distance. This is essential for some forms of sports and wilderness photography. The reflex viewfinder ensures the correctness of the vision image regardless of the type of lens installed. There are a number of old models showing some of the viewfinder being cut off with very long focal lengths, and this is due to the fact that the reflective mirror is not large enough to reflect the whole picture. With the exception of simple Exa models, we find that this does not affect the process of taking pictures.

4 Do all lenses have the same structural structure?

Ordinary lenses can contain the same optical structural structure, regardless of its focal length, and the longer the focal length, the longer the lenses are mounted farther from the film. Thus, for example, a 500 mm lens should be at the end of a half-meter tube, while it should be The center of the lens measures 15 mm away by only 15, and in both cases we find that this is not appropriate, and therefore most modern wide-angle lenses and focal lengths are modified shapes to change their natural size without affecting their length or long mm. focal length
Eating and pregnancy. Inverted telephoto lenses are longer than their focal length, and this structure is used to secure space for the reflective mirror in wide-angle lenses for SLR cameras. Some older, ultra-wide formats use a locked camera mirror with a separate viewfinder. As for the standard lenses for SLR cameras, they are also one of the lenses for many inverted telephoto lenses for telephoto photography, and this allows the installation of lenses with much wider apertures without interfering with the mirror box.