The space enclosed by the MTF curve, the horizontal axis and the vertical axis, the larger the area, the better, and the better the lens imaging performance. The flatter the MTF curve, the better. The flatness indicates the imaging uniformity of the edge and center of the lens. 2. The closer the sagittal curve and the meridian curve, the better, and the more consistent the imaging in different directions. 3. The low frequency curve represents the contrast characteristics of the lens, and the high frequency curve represents the resolution characteristics of the lens.