What are the specifications for the grid?

The second point that the grid needs to pay attention to. Note that the distance between the focus and the cassette is referred to as the focal length.

The focal length should correspond to the focal length of the grid. However, it is difficult to make the two opposite each other due to the difference in the position and position of the actual shooting. At this time, a range value should be specified. The range of the focal length of the specified range cannot be greater than or less than 25% of the focal length, or the edge portion of the effective area of the grid must have a pass rate of less than 40%. value.

Author：Alina