What is the movement of the lens group during the adjustment of the focal length of the lens and the

Typical examples are the VOIGTLANDER Zoomar 36-82, the SOM 16mm cinema camera PAN Cinor 20-60, etc., and you can see that the movement of the front and rear lenses changes the focal length while the focus remains on the negative. It depends on how you understand the difference in mechanical compensation, because there is also mechanical motion here. Mechanical compensation, in my understanding, is that each group has basically corrected the aberration, which is nothing more than the difference in distance affects the size of the image, and optical compensation is the change of the overall optical path, in which various aberrations are constantly changing between the lens groups.

Of course, this is not necessarily true, after all, Kingslake didn't say it, and I'm actually engaged in translation, not optics) In fact, the focus of this type of lens is "repeatedly" drifting around the focal plane while zooming, and it is not 100% fixed. By adding a powerful fixed focal lens group, the effect of this drift can be reduced. In short, there are not many such lenses, but the movement of this lens is unidirectional (although the distance of movement and the focal length change disproportionately) because it is an overall movement.

The prime head focal length is fixed, which is the most basic. The image of the plane where you shoot will be clearly displayed on the corresponding focal plane, and you have to move the negative (sensor) back and forth to the place that coincides with the focal plane in order to image, this process is called focusing. Different planes correspond to different focal planes, so it is necessary to focus on objects at different distances.

The reciprocal of the object distance plus the reciprocal of the image distance is equal to the focal length. Finally, "When focusing, it is recommended to focus on the telephoto end first and adjust it to the appropriate focal length, so that the focal plane will not change in the process?" "I think you have the answer.

For lenses that are 100% zoom-proof, the telephoto end "zooms in" the image to focus more accurately, and then zoom, and the focus is not shifted, so it can shoot directly. - For lenses that can't achieve 100% zoom, the focus shifts after zooming, which is not advisable. <>

No, lenses whose focal length can be changed during use are called zoom lenses.

A zoom lens is a field of view that can be changed within a certain range to obtain different widths and narrownesses.

The number of camera lenses of different sizes and different areas of view. The zoom lens can change the shooting range by changing the focal length without changing the shooting distance, so it is very beneficial for image composition.

Focal length is a measure of the concentration or divergence of light in an optical system, and refers to the distance from the center of the lens to the focal point of light concentration when collimated light is incident [1]. Optical systems with short focal lengths, such as slag head telephoto.

The optical system has the ability to concentrate light more than the bridge. In simple terms, focal length is the distance between the focal point and the center point of the mask. In the camera, the focal length f and image distance < 2f to image.

Prime Lens (Prime Lens

Refers to a lens that has only one fixed focal length and no focal length.

One said, or only one vision. Fixed focal length lenses do not have a zoom function.

The design of the prime lens is much simpler than that of the zoom lens, but the general zoom lens will have an impact on the imaging during the zoom process, and the biggest advantage of the prime lens over the zoom machine is that the focusing speed is fast and the image quality is stable.

Quite a few digital cameras have prime lenses.

The images of moving objects are sharp and stable, the focus is very accurate, the image is fine, the graininess is very light, and the metering is accurate.

Tilt-shift lenses refer to lenses that can move the optical axis. The lens can swing to change the perspective effect of the special lens.

Shift-focus photography refers to shooting in which the background is completely blurred to make the subject stand out, often with a large-aperture lens and a completely open aperture for shooting, or using a telephoto lens. The opposite method of shooting with focus shift is called pan focus, and it is often used in ** where the sense of distance and proximity is emphasized.

Tilt-shift lenses.

There are lenses in the lens that can change the focal plane, and the ** in the same focus plane can be shot with the upper and lower half clear or the left and right half clear**, which is generally used in professional fields, such as advertising, architecture, etc.!

Adjusting the distance between the lens and the focal plane so that the shooting can get () is the function of the focus adjustment before the setting.

a.Color-saturated scenes.

b.Right**.

c.Hui Hui Hui with the right tone to accept the image.

d.Crisp images.

Correct answer: Clear image of Shitong.

Adjusting the distance between the lens and the film plane so that the film spike can be touched () is the function of the focusing device.

a.A scene full of color.

b.That's right**.

c.Images with the right tone.

d.Clear image (positive pants smart answers).

The zoom lens can easily shoot targets at different distances, so why do you have to move the camera back and forth so often when shooting?

Although the zoom lens can easily shoot targets at different distances, there are two points that are clearly stated: first, the angle of view at the telephoto end is small, and the angle of view at the wide-angle end is large; Second, the depth of field at the telephoto end of the lens is small, and the depth of field at the wide-angle end is large. For example:

If you need a large angle of view and a small depth of field when shooting, you need to notice the telephoto end shooting button, so that the lead camera position of the manuscript needs to be moved back; If you need a large angle of view and a large depth of field, you need to shoot with a wide-angle end, so that the camera needs to be moved forward. Another point is that the zoom range of the zoom lens is sometimes not sufficient when shooting on location, and the camera needs to be moved.