Wonders of active optics: letters

The video sequence shows the real images, now with several stars in the field. The integration time was 0.8 seconds. This is longer than the time scale of atmospheric turbulence and the additional deformation of the stellar images due to the seeing is practically the same for all of the images. If a shorter integration time would have been used, the images may have looked more different, especially those that are farthest apart. This is because of the relatively small size of the air cells that cause the seeing effect, and whereby the light from different stars in the field is subject to different atmospheric disturbances.