It is a special photographic lens, which can be used for macro or close-up photography without installing close-up accessories such as close-up lens, close-up ring and close-up track leather cavity. It is a special photographic lens, which is used to shoot tiny objects or re-create small pictures. The resolution of this lens is quite high, the distortion aberration is quite small, and the contrast is high, and the color reproduction is very real.

Fixed focus lens:

The focal length is fixed, and a lens with the same focal length is called a fixed-focus lens, which cannot bring the scene closer or farther. The advantages of fixed focus compared with zoom are better imaging quality and easier aperture enlargement. The disadvantage is that you can't zoom, and you can only compose the picture by the photographer's action. For example, the commonly used 50mm lens is a fixed focus lens.

Focal length refers to the position where parallel light illuminates the lens and focuses on the image. For the lens with Dan Toujing structure, it is a fixed focus lens.

The pearls in the picture are measured in units of 100 microns, and can be photographed with a small aperture.

I hope I can help you.