Lens optical axis test

lens optical axis test

lens optical axis test, photography is commonly used in our lives, photography has many skills and many lenses, and many people may not know much about lenses. So, what is the lens optical axis test? There may be many people who don't know it. Take a look. Lens optical axis test 1

1. Since the axis-shifting lens is to be used, the lens must be installed first. After the axis-shifting lens is firmly installed on the fuselage, it is necessary to confirm that the offset and inclination functions are the default settings. In addition, when keeping the lens, the inclination angle and offset position should be restored.

2. After the lens is installed, try to use a tripod when taking pictures. Because you have to adjust the direction and angle when using this lens, the effect and operability of having a tripod are completely different.

3. In order to grasp the shape of the subject more closely when shooting, you can select "Grid Line Display" from the real-time setting menu. Set the grid line, which is convenient for users to accurately control the viewing range. Especially when using shift lens, this setting will make your shooting more controllable.

4. Adjust the shape of the subject by shifting, and adjust the shape of the subject by manually focusing and then shifting. In the process of shooting, try to keep the horizontal position relationship between the lens and the subject, and at the same time compensate the shape of the subject.

5. Control the focal plane by adjusting the tilt angle

Adjust the shape of the subject before the tilt angle operation. In the case of small depth of field, in order to make the subject focus as a whole, a focal plane can be imagined. The key to setting this imaginary focal plane is to make the required depth of field as small as possible. In this way, even if the aperture value is small, it is easier to focus on the whole subject. The inclination angle can also effectively prevent the resolution reduction caused by diffraction phenomenon caused by too small aperture shrinkage. The figure shows the depth of field and imaginary focal plane considered when shooting. Lens optical axis test 2

1. Adjust the platform and the flat plate: firstly, place a flat plate with good flatness on the platform, adjust the platform to make the plane of the flat plate in a horizontal state, and place a prism on the flat plate;

2. Adjust the platform and collimator: adjust the platform so that the parallel light emitted by the collimator on the platform is reflected by the prism and then self-collimated, so that the optical axis of the collimator is parallel to the plane of the flat plate;

3. Adjust the platform and collimator: remove the prism and adjust the collimator on the platform. The reticle on the focal plane of the collimator is imaged on the focal plane of the collimator, so that the reticle on the focal plane of the collimator coincides with the reticle of the collimator, and the optical axis of the collimator is parallel to the plane of the flat plate. At this time, the optical axis of the collimator is parallel to the optical axis of the collimator and the plane of the flat plate.

4. Measure the parallelism between the optical axis of the optical system to be measured and the base surface of the flat plate: place the optical system to be measured on the flat plate of the platform, and aim the lens of the optical system to the collimator, so that the image formed by the reticle on the focal plane of the collimator is displayed on the display, and the electric reticle image of the display is displayed in the center of the display; When the optical axis of the measured optical system is parallel to the base plane of the flat plate, the two reticle images are completely coincident; When the optical axis of the optical system to be measured is not parallel to the base plane of the flat plate, the two cross-shaped line images are not coincident, the optical axis of the collimator is made parallel to the optical axis of the optical system to be measured by adjusting the platform, and the image formed by the reticle on the focal plane of the collimator through the optical system to be measured on the display is coincident with the image of the electric crosshead; Then take down the optical system to be tested. At this time, the optical axis of the collimator is not parallel to the optical axis of the collimator, and the cross line of the collimator is no longer coincident with the cross image of the collimator imaged on its focal plane. The deviation angle between the collimator and the two optical axes is measured by using the reading drum of the collimator, and the parallelism of the optical axis of the optical system and its installation base surface is completed. Lens optical axis test 3

Zoom in and focus manually. If it is clear, it is out of focus.

The optical axis deviation is generally caused by the lens being violently bumped. Of course, some cheap lenses use plastic lens barrels, which will also cause the optical axis deviation due to wear and deformation after long-term use. But it doesn't mean that the new lens will be fine. There are so many lenses in a lens, even if one of them is installed a few tenths of a millimeter, it may cause serious image defects. Therefore, if you can afford it, try to buy high-end lenses, or at least assemble them more carefully.

The influence of optical axis deviation on the image is that the imaging of local area is not clear. For example, the clarity of one of the four corners of a photo is obviously poor, which is basically caused by the deviation of the optical axis. Or, half of the images are unclear, which is also the optical axis deviation (or the camera cmos itself is biased).

If a photo is not clear near the edge, strictly speaking, the range of a circle radiated from the center of the photo is not clear. This is not a fault, but a phase field bending or weakened edge resolution, which belongs to the choice in lens design. Phase field bending and edge resolution weakening are common in wide-angle lenses, and even some top-level lenses can't escape this column.