How can SLR shoot the effect of near reality and far virtual or far reality and near virtual?

This belongs to the depth of field effect.

The so-called depth of field is the range that can still be clearly seen before and after when the focus is on a certain point. It can decide whether to blur the background to highlight the subject or shoot a clear background.

In the photos of flowers, insects, etc., the background is often blurred (called small depth of field). However, when taking commemorative photos, group photos, scenery and other photos, the background is generally as clear as the subject (called large depth of field).

Photographs taken with a large aperture (small F value) will have a shallow depth of field, while photographs taken with a small aperture (large F value) will have a deep depth of field. For example, photos taken with f/2.8 aperture must have a shallower depth of field than those taken with f/8.

Aperture, the distance between the lens and the subject are important factors affecting the depth of field;

1, the larger the aperture, the smaller the depth of field, and the smaller the aperture, the greater the depth of field.

2. The longer the focal length of the lens, the smaller the depth of field; Conversely, the greater the depth of field.

3. The closer the subject is, the smaller the depth of field is, and the farther the subject is, the greater the depth of field is.