Help with Star Testing My SVP120

I recently got an Orion Sky View Pro 120 achromat and it does a good job on planets, the primary reason I got it. But the star test shows zone errors. Is it reasonable to think that another one would perform better? I am attaching the star test (inside focus on left, outside focus on right). This was shot through a green filter.

I am trying to learn to evaluate star tests. I am getting the Suiter book.

Any comments apprecitated!
Bob

Attached Image:

You will not get a hand corrected lens at the price point of this telescope. These lenses are all manufactured in high production using machine polishing on high speed plastic laps. The lenses are not made with pitch with any kind of final figuring. Typically some tweaking of overall correction is made by adjusting the thickness of the airspace. If the set is undercorrected, the lens cannot usually be nulled beyond a certain point. If overcorrected, then incresing the spacer thickness will allow spherical nulling, but will also change the color correction a small amount.

The images you posted are a bit out of focus to determine the amount of spherical error, but I would guess the lens is somewhere around 1/2 wave or worse.

When you take out-of focus images, take 5 sets. Two images far out like the ones you did - these will show zones. Two closer to focus with perhaps 2-3 Fresnel rings showing - these will show spherical error and whether astigmatism and coma are present. Finally, one at focus to show any residual scatter, color error and other defects that occur at actual focus.

Rolando