So I got this TSA102 last year off of AM. I have done several upgrades to it to include the starlight FTF3035B A Feathertouch 3.0" dual speed focuser with 3.5" draw tube. It replaced the Tak draw tube and starlight micro focuser. The tak draw tube had been used by the previous owner for binovewing and had taken a toll on the functionality of the focuser. I was able to pick up the SL draw tube focuser and finder used from a nice gentlemen from Australia. In addition I was lucky to Paul Leuba locally and had him do a bench test on the scope. Here is the summary of the bench test.
There are no real zones to speak of and I saw no polishing artifacts. The lens is slightly under-corrected this could be caused by the lens being at a different temperature then the surrounding air. Usually a lens will show marked undercorrection as it reaches thermal equilibrium.
Here is the breakdown by color:
White its slightly undercorrected.
Green very slightly undercorrected.
Red its slightly undercorrected
Blue is slightly overcorrected.
The red and the blue are almost always opposite with one being undercorrected and the other being overcorrected. Its done this way to balance the ends of the spectrum. Best correction is always in green. And your scope is no different.
There is no turned edge and the optic is very smooth.
Summary: The lens is overall quite good; really good; high contrast etc.