Then please follow my introduction to return to the basic optical knowledge of junior high school

1. When the object distance is greater than 2 times focal length, the image distance is between 1 times focal length and 2 times focal length, forming an inverted and reduced real image, at this time the image distance is less than the object distance, the image is smaller than the object, and the object and the image are different sides.

Applied to cameras and cameras, the working principle of the human eye is basically the same, but the human eye can zoom

2. When the object distance is equal to 2 times the focal length, the image distance is also at 2 times the focal length, forming an inverted, equal large real image. At this time, the object distance is equal to the image distance, the image and the object are equal in size, and the object image is different.

The imaging principle can be applied to the focal length measurement of our optics

3. When the object distance is less than 2 times the focal length and greater than 1 times the focal length, the image distance is greater than 2 times the focal length, and the inverted and enlarged real image is formed. At this time, the image distance is greater than the object distance, the image is larger than the object, and the object image is different.

The imaging principle can be used in projective imaging instruments such as projector

4. When the object distance is equal to 1 times the focal length, it becomes a upright and enlarged virtual image. At this time, the image distance is greater than the object distance, the image is larger than the object, and the object image is on the same side.

This imaging principle also explains why convex lenses are also called collimating lenses

5. When the object distance is less than 1 times the focal length, it becomes a upright and enlarged virtual image. At this time, the image distance is greater than the object distance, the image is larger than the object, and the object image is on the same side.

The use of the imaging principle is also common, such as a magnifying glass in life