Fix lenses are lenses that have only one focal length (or usually also called a prime lens). This means that this type of lens only has one field of view (100 ° yes 100 ° only, 80 ° yes 80 ° only), and cannot be replaced. When you use this lens, as long as you do not move forward or backward, you cannot make your photo object appear larger or smaller in the frame.
The only way to make the subject of a photo seem bigger is to go a few steps, and the only way to make it look small is to try to back out.
Fix lenses have only one size of focal length, for example 50mm. Many variations in focal lengths on fix lenses, ranging from fisheye to telephoto. Example: Canon 800mm f / 5.6L IS, Sigma 35mm f / 1.4.
