on one edge or corner of the field while the rest of the stars appear sharp this implies the primary mirror is slightly tilted and not perfectly aligned with the optical axis of the light collimating system this is normally compensated for by adjusting the secondary mirror but with the mirror removed the coma effect is diminished by properly aligning the light collimating system this is done by taking a single short exposure of a star field and then by simply adjusting one set of the push screws 22 and pull screws 20 this will tip one side of the light collimating system outward a second image will reveal if the collimation was successful if no improvement is seen a different pair of push and pull screws should be adjusted it may be necessary to refocus during adjustment to see the best results a variety of cameras will work with the light collimating system but there are some limitations the camera cannot be too large or it will obstruct too much of the telescope aperture thus it follows that larger telescopes can use larger cameras also the size of the sensor that can be fully illuminated by the light collimating system is dependent on the size of the telescope larger scopes allow larger lens elements to be used in the light collimating system allowing bigger sensors to be illuminated imaging with a.