Why is Nikon F mount called AI mount? Can't we just call F port? What exactly does AI mean?

Nikon’s SLR mount has always been called F-mount. As for the term "AI port", it is not strict. A more colloquial term refers to AI-type lenses. AI is actually a type of lens, not a mount. The F mount can use A, AI, AI-S, AF and other types of lenses.

Explain the meaning in detail: The name of the F mount comes from the name of the first SLR produced by Nikon in 1959 (Nikon F). Its mechanical structure has basically not changed for more than 50 years, so 50 years ago The lenses can also be used on modern digital SLRs. As for why that SLR is called Nikon F, it’s really hard to test. It’s probably the abbreviation of Foto.

AI is the abbreviation of Automatic Indexing. The common Chinese translation of this phrase is "maximum aperture transmission technology". I think this translation is very difficult to pronounce and difficult to understand. In fact, it is a technology that allows you to use the camera body to control the lens aperture. With this technology, no matter what the aperture is set to, the maximum aperture can always be maintained during normal viewing. Only when the shutter is pressed, the aperture changes to the set value.

Extended information:

Nikon advantages:

1. Close-range correction system:

By moving several lens groups independently This method can effectively correct this kind of field curvature, and you can get a smooth picture even when shooting at close range.

2. Internal focusing:

This focusing method divides the lenses into the front group, the middle group and the rear group. Only the middle group of lenses moves to achieve focus.

3. Nanocrystalline coating:

Nikkor’s nanocrystalline coating originally came from Nikon’s achievements in the field of semiconductor manufacturing technology. It is an anti-reflective coating. A coating with a lower refractive index is used, and its main feature is its fine nano* crystalline particles. These crystalline particles effectively prevent reflection of all visible light waves in the lens (380nm to 780nm), working in a way that goes beyond traditional anti-reflective coatings.

4. VR (Vibration Reduction):

In the NIKKOR Vibration Reduction System, the VR sensor in the VR lens unit automatically detects camera shake information. This sensor is inside the lens. Continuous motion aligns the optical axis with the camera's imaging sensor, thereby reducing image blur. The system's effect is equivalent to increasing shutter speed by up to 4.5 stops*, helping photographers achieve clear shots when shooting sports scenes and low-light landscapes, as well as when shooting handheld.

5. Low dispersion (ED) lenses:

The low dispersion (ED) lenses developed by Nikon can greatly reduce the dispersion caused by prisms. The low dispersion properties of these low dispersion (ED) lenses significantly reduce the secondary spectrum. For lenses using ordinary optical lenses, the longer the focal length, the more difficult it is to correct the chromatic aberration that causes chromatic aberration rough edges.