What you have described is a common issue reported by many who start collimating with both a laser collimator and a collimation cap. Think about it: The laser beam hits a tiny area on the secondary mirror and does not interact with the secondary mirror edge. Why would you expect a single laser beam to center/round the secondary mirror under the focuser? The secondary mirror alignment consists of two completely different and independent alignments. This is the cause of confusion. The single lase