Optically: It takes years of searching to find a commercial SCT with exceptional optics. This is one such scope! Star test are excellent and Planetry performance is exceptional. Star testing shows no astigmatism,no zonal defects, minimal spherical aberration and what impressed me the most,a very smooth optical surface. The focus snap test is exceptional coming to focus at precisely one point.
Mirror Shift: Mirror shift in this scope is a good as it gets. I estimate 5-10 arc seconds at most and it's not even noticeable with low powers. At 400X's with a narrow feild 5mm Ortho image shift is not a problem. This is great for plantery webcam imaging where your subject can lterally go off the chip while focusing.