“FNo. 2.0” means that the aperture value (F-number) of the lens is 2.0, which is the core parameter for measuring the light intake capacity and depth of field range of the lens. The following is a detailed analysis from the aspects of definition, function, and application scenarios:

1. Definition of aperture value (F-number)

Formula:FNo.=D/f

f: focal length of the lens (unit: millimeter, such as 50mm).

D: actual physical diameter of the aperture (unit: millimeter).

Example: If the focal length is 50mm and the aperture diameter is 25mm, then FNo.=25/50=2.0.

Physical meaning:

FNo. 2.0 means that the aperture opening size of the lens is 1/2 of the focal length. The smaller the value, the larger the aperture and the more light intake.

2. The core function of FNo. 2.0

Light intake control:

The larger the aperture (the smaller the FNo.), the more light enters, which is suitable for low-light environments (such as night scenes, indoors).

The aperture of FNo. 2.0 is two stops larger than that of FNo. 4.0, and the amount of light entering is 4 times that of FNo. 4.0 (each aperture difference is √2 times, and the amount of light entering is 2 times different).

Depth of field adjustment:

The larger the aperture, the shallower the depth of field (the stronger the background blur effect), which is suitable for portrait and close-up photography.

FNo. 2.0 can create a strong background blur and highlight the subject.

Shutter speed and ISO:

A large aperture (FNo. 2.0) allows the use of faster shutter speeds (reduce shake) or lower ISO (reduce noise).

3. Practical application scenarios

Portrait photography:

FNo. 2.0 can achieve a shallow depth of field, blur the background, and highlight the subject.

Night scene and low light shooting:

A large aperture increases the amount of light entering, lowers ISO or increases shutter speed, reduces noise and blur.

Video shooting:

A shallow depth of field can enhance the film feel of the picture, suitable for narrative videos.

Macro photography:

A large aperture can compensate for the light loss during macro shooting, while controlling the depth of field.Recommended Reading:5MP fisheye S-mount mini lens.

4. Relationship with other parameters

Relationship with focal length:

Under the same FNo., the longer the focal length, the larger the aperture diameter (such as the aperture diameter of 50mm F2.0 is 25mm, while the aperture diameter of 85mm F2.0 is 42.5mm).

The longer the focal length, the shallower the depth of field (even if the FNo. is the same).

Trade-off with lens design:

Large aperture lenses (such as FNo. 1.2, 1.4) are usually larger and more expensive, and may have problems such as reduced edge image quality and chromatic aberration.

FNo. 2.0 strikes a good balance between aperture size, cost and image quality.

5. FAQ

Q: Is FNo. 2.0 suitable for all scenes?

A: It is not suitable for scenes that require a large depth of field (such as landscapes and buildings). In this case, the aperture needs to be reduced (such as FNo. 8-16).

Q: Is a lens with FNo. 2.0 necessarily more expensive than a lens with FNo. 4.0?

A: It is usually more expensive, but it needs to be judged comprehensively based on factors such as focal length, brand, and image quality.

Q: How to calculate the difference in light intake between different FNo.s?

A: Each aperture differs by 2 times the amount of light intake. For example, FNo. 2.0 is 2 times that of FNo. 2.8 and 4 times that of FNo. 4.0.

6. Summary

FNo. 2.0 means that the lens aperture is larger and is suitable for scenes that require a shallow depth of field, such as low light, portraits, and videos.

Selection suggestions:

If you need a strong background blur or low-light shooting, give priority to lenses with FNo. 2.0 or smaller.

If you need a large depth of field or portability, you can choose a lens with FNo. 4.0 or larger.

By understanding the meaning of FNo. 2.0, users can choose the right lens according to their needs and optimize the shooting effect.