Does the focus screen affect the focus?

The focus screen is exhausted. If it is autofocus, it will not affect. If it is manual focusing, as long as the focusing screen is not in the focusing area, it will not affect your observation of focusing operation. Don't worry after using it. This may improve your photography skills.

The focusing screen is equivalent to the ideal film plane, that is, the distance from the mirror to the focusing screen is equal to the distance from the mirror to the film plane. Before exposure, the focusing screen replaces the film plane. When the focus is accurate, a clear image will appear on the focus screen. Due to the principle of optical reflection, the picture on the focusing screen is reversed from left to right, and can only be corrected by a five-sided viewfinder.

At present, all focusing screens are frosted glass Fresnel lenses, which have the advantages of bright and uniform brightness. When the focus is not correct, the image on the focused screen is not clear. In order to cooperate with more accurate focusing, image splitting and micro-edge ring devices are generally installed in the center of the focusing screen. When the focus is not correct, the object image in the center of the focused screen is divided into two images. When two segmented images are merged into one, it shows that the focus is accurate.