Zoom Lens

Zoom lens is a kind of camera lens that can change the focal length in a certain range. So as to get different width of view angle and different sizes of images. Also, to get different scene ranges. Zoom lens can change the shooting-range by changing the focal length. And also without changing the shooting distance. Therefore, it is very conducive to the picture composition. A zoom lens can also play the role of several fixed focus lenses. When traveling, it not only reduces the number of carrying photographic equipment. At the same time, it also helps to save the time to replace the lens.

Common sense of lens

The size of the aperture f value, f is the transmittance of the lens. The larger the aperture f is (the smaller the f value is), the higher the transmittance of the lens is. If a lens is set with multiple apertures, the larger the value of the aperture, the smaller the aperture. Meanwhile, this means the less the luminous flux.

What I want to show you here is that the f value of lens in the ideal state can reach 1.0. Restricted by manufacturing technology, price and others, f value can never reach 1.0.

For the projector, the lens is the last link in the light path of the projector. It is important for the quality of the lens and whether the aperture value can be minimized. For they are directly related to the brightness. The aperture size is inversely proportional to the f value. The smaller the f value is, the larger the aperture is. And the higher the brightness of the projection image is.

Not necessarily the projector lens is big, its f value is big. It is closely related to the focal length of the lens. For aperture projector, it is possible that the f value of a small lens is smaller than that of a large lens.

Zoom lenses include Zoom in shot, Zoom out shot and The Hitchcock zoom.

Zoom in means that the focal length of a lens changes from small to large. For example, zoom in from 20 mm to 85 mm. Because it is to change the focal length of the lens. Then the view of perspective and perspective relationship of the picture will change accordingly. The focal length changes from small to large. It will shorten the distance between the background and the subject. Otherwise, it will widen the distance between the subject and the background. Changing the focal length will also change the result of virtualization. Under the same iris, the longer the focal length is, the more obvious the effect is.

In this way, zoom in is usually used to highlight the subject / a detail in the picture. Then separate it from the noisy background. Zoom out is usually used to show the environment / atmosphere of the subject.

Zoom shot usually attracts the audience with its changing the perspective of the picture. We should pay close attention to this. Of course, it can also be used as a special artistic effect. Film is an art form that composed of lens, picture and color. Each lens has its own unique charm.

The Hitchcock zoom

Hitchcock is a unique method combining dolly shot and zoom shot. Its main technique is to change the position and focal length at the same time. As to change the perspective of the background with the same size of the main body. This is a very visually striking technique of expression.