As you move onto the more expensive zoom lenses, they maintain a constantaperture.
当你继续研究比较昂贵的变焦镜头时，你会发现它们有着恒定的光圈。
2
By using the aperture synthetic wideband beamforming algorithm, the theory of designing the conventional filter is improved, and a wideband constant beamwidth is reached in the appointed bandwidth.
The projection optics is designed for a constant field angle and entrance pupil. Thus image always fills entrance aperture and view field of the test optical system.