My lovely new 20″ scope appears to need glasses. Seems as though Skywatcher didn’t make the mirror as well as they should have, and there is somewhere around one to two waves of spherical aberration present on the mirror. This is ruining the fine contrast on planets and making the scope a little frustrating to use. Currently working with the vendor to get a replacement mirror.
There is also another issue with the scope, where the primary mirror support structure has enough movement present under the change in altitude, to ensure that the scope cannot maintain collimation. My investigations so far suggest that the movement is present only in the interface between the glass and the central aluminium column that mounts the mirror to the rest of the telescope superstructure, so that’s another reason to require the replacement of the mirror as I cannot easily perform a repair on that interface, and given it’s under warranty I’m not going to touch that one.
The third problem I was having was with the quality of the GoTo computerised drive system. It turns out that one of the core components that supports the telescope “tube” had been bent out of place during a shipping accident, and was interfering with the correct operation of hte altitude portion of the drive. One removal and re-addition later, that component is now in the correct position and I’m now getting the desired target object somewhere in the eyepiece field of view after a slew.
My impressions of the scope are still good, though tempered by the (hopefully) temporary optical and mechanical issues present. There are some things I really like such as the ease of setup and takedown and the subsequent ease of storage that results from that. The drive accuracy once pointed on target means I can do lucky imaging of deepsky objects with some interesting results. The requirement for a small stepladder is not an issue for me on a lawn, but may be an issue on an apartment terrace. Now that I have the best of eyepieces and a Paracorr, I have some pretty low-power views when it is dark, but the high power views definitely have suffered with the aberrations present.
There does exists the capability for this scope to be a fantastic performer, just not yet.