Do the four lenses of the cat's eye need distance?

Need distance. Because this will make the imaging clearer, the distance between the objective lens and the eyepiece is about 3cm, and there are two plane concave mirror in the middle. The installation steps are as follows:

1, first unscrew the cat's eye equipped with the property. The eyepiece is placed inside the door and the objective lens is placed outside the door.

2. Unscrew the lens part, and you will find that there are four lenses: the largest is the objective lens (concave lens), the plane concave lens 1, the plane concave lens 2 and the eyepiece (convex lens).

3. Lens installation sequence: the eyepiece is at the innermost part of the lens barrel, then the plane concave lens 1 (concave facing the objective lens), the plane concave lens 2 (concave facing the objective lens), and the objective lens. After assembly, install it.