Объектив + два зеркала + корректор + диагональ...
А вот, что сам автор про юстировку пишет на клаудях:
As for collimation, the correction lenses are mounted on a precision machined rail, and are aligned to within 10 microns in each cell. Final alignment is by tweaking the large fold flat, but as I use strong springs, it doesn't move unless really provoked.
Visually, there is absolutely no chromatic aberration at any power, and objects such as M42 are just breathtaking. Stars are tiny pin points. If you are going to do imaging, I would suggest RGB as CCD's are not as forgiving as the human eye.
These designs are critical, but not impossible to make. The collimation didn't move one iota after a 150 mile drive in the back of my old 944 Porsche. This is one big refractor that can go anywhere.