Optical axis of photographic lens

The optical axis of the camera lens, photography can show the world in one's eyes to others through the fear and technique of death, and can also record many beautiful things. Many people want to learn photography, but they still have a lot of theoretical knowledge about photography. Let's share the optical axis of the camera lens.

The optical axis of the photographic lens is 1, the center line of the beam (column), or the symmetry axis of the optical system. The observation optical axis is located beside the optical axis of the photographic lens and parallel to each other.

Axis shift, as the name implies, means that the optical axis of the lens can move, including the movement of the optical axis and the rotation of the optical axis, thus changing the perspective effect of the picture, including blur and distortion. The original intention of shifting the axis of a large frame is not to shoot creative effects, but to ensure that the camera has a clearer depth of field range and more accurate distortion control in a large frame.

The main feature of axis-shifting camera lens is that the main optical axis of the whole camera lens can be translated, tilted or rotated on the premise that the plane position of the camera body and the film remains unchanged, so as to adjust the perspective relationship of the shot image or focus the whole area.

The reference clear image field of the camera lens with shifting axis is much larger, which is to ensure that the main optical axis of the camera lens can still get a clear image after translation, tilt or rotation.

Extended data

Optical axis classification

1, astigmatism axis

The astigmatism axis represents the axial direction of the lens according to the direction in which your cornea has the greatest curvature and the weakest refractive power. Whether the line in a certain direction seen by the astigmatism eye is clear or fuzzy depends on the axial direction and degree of astigmatism. Generally speaking, the direction of the blurred line on the astigmatism eye surface is the axis direction of the negative lens worn by the eye.

2. Secondary optical axis

Short axis refers to any straight line passing through the curvature center of a single spherical mirror but not through the aperture center (vertex) of the spherical mirror. For a thin lens, when the refractive index of the space where the incident light is located is the same as that of the space where the outgoing light is located, any straight line passing through the optical center but not through the curvature center of the refractive sphere is a secondary optical axis.

3. Main optical axis

The principal axis is also called the "principal optical axis". A straight line passing through the centers of two spherical surfaces of a lens is called. The optical axis of a single spherical mirror is a straight line passing through the center of the spherical surface and perpendicular to the mirror surface; The optical axis of the lens or coaxial optical group is the connecting line of the spherical center of each lens. It should be noted that any straight line passing through the optical center can be called the optical axis of the lens, and they are generally called sub-optical axes.

Optical axis of photographic lens 2 1, what is the optical axis?

Optical axis: Also called "camera axis". Refers to the line between the camera and the subject (the object you shoot) when shooting. As shown in the figure below:

This line is nothing, you need to imagine its existence with your head. It's actually quite simple. What you shoot, the camera and TA are connected into a line, and this line is called the optical axis (camera axis).

When we study all lighting techniques or discuss the lighting mode of photos, we should take the optical axis as the only basis and the optical axis as the most fundamental basis. Otherwise, the so-called light level research cannot be established.

2. Use the scene?

For example, the subject you shoot is a character, and the subject is facing you. At this time, the lights are in the right front and right top of the subject.

Then when we say the position of this light source, we can't use the main body, but the optical axis.

The correct statement should be that this light source is located on the left side of the 45-degree cross section of the optical axis, that is, from top to bottom, as shown below:

In plan view, that is, in longitudinal section view, its height is 30 degrees. As shown in the figure below:

When we study light level, angle refers to the angle between light source and optical axis. Determine the angle between the transverse section and the longitudinal section to determine the position of the light source. Please fill in the picture above. If you can imagine this two-dimensional plane as a three-dimensional space, you will understand. It will be easier to learn lighting in the future.

The optical axis of the photographic lens is 3 1. Learning light level analysis can better understand the photo shooting process and facilitate the imitation of learning progress. Can also better communicate lighting skills with peers;

2. This invisible line between the lens and the subject is called "optical axis" and "central axis";

3. All light level analysis or light level arrangement should be based on the "central axis";

4. Cross-section refers to the range that rotates 360 degrees to the left or right with the central axis as the benchmark and the subject (model) as the center point;

5. The longitudinal section refers to the range that rotates 360 degrees upward or downward with the central axis as the benchmark and the main body (model) as the center point;

6. To judge the position of the light source, two specific angles should be defined, namely the transverse section and the longitudinal section;

7. When the model rotates, if you want the same light and shadow effect, then the light source should also rotate at the same angle;

8. Light level analysis and description that is not based on the central axis are all hooligans ~