What are "open focus" and "soft focus"

When shooting, using a soft-focus lens or adding a soft-focus filter in front of the lens can make the image receive a delicate and soft effect, which is called soft-focus photography.

In the design of general photographic lens, various technical means are often used to solve the problems of aberration and chromatic aberration to ensure clear and sharp imaging. However, in order to pursue special soft-focus effect and create a soft picture atmosphere, there are specially designed soft-focus lenses. For example, designing a soft-focus portrait lens and consciously increasing the residual value of some aberrations can make the image clear and soft, thus covering up the facial defects of the characters and increasing the artistic effect of the photos.

In pursuit of soft focus effect, there are two common methods besides using soft focus lens: one is to add soft focus filter or tulle in front of the lens when shooting. The second is to add a soft focus filter or tulle in front of the lens of the magnifying glass when enlarging the photo.

The soft-focus effect of soft-focus lens is completely different from that of ordinary lens. In essence, soft-focus lens produces ghost, clear real image and out-of-focus virtual image, which overlap.

The most important feature of soft light photographic lens is that a porous metal sheet perpendicular to the main optical axis is set in the perspective optical path of the lens. When the light of the subject enters the lens, it will spread through the small holes in the metal plate, so that the final image on the film plane will be softer.