[Starkler (Geoff)]

I just gave my 20mm gso superview a very quick first light, comparing it to the 20mm plossl originally supplied with my GS 250mm dobsonian.

The night was cloudy and I was able to peer through a gap long enough to do a quick test viewing of the cluster M7 in Scorpio.

Now for what everyone wants to know, how good is it?

It has a wider field than a 20mm plossl. Im not able to quantify this without doing a star drift test, but as a guess its something like 60-65 degrees.
On axis it appears to perform well , focussing sharply, but the bad news is that the extra field over the plossl comes with a cost of distortion and astigmatism, manifesting itself as classic "seaguls" in the outer 20% or so of the view.

As a person used to using pentax xl's and teleview panoptics, I cant say that the GSO comes close in performance at f5, but at $69 one cant complain too much.
When the moon comes back I'll see how it goes for ghosting and internal reflections.

Strengths :

Well made, fully multicoated, lens subassembly comes out for easy cleaning, great price for the build quality.

Weaknesses:

Eye relief about the same as an equivalent focal length plossl, with "seaguls" present in the extra FOV you get over a plossl at f5.

Conclusion:

Great value for money in the budget price range and possibly wont be beaten by anything costing less than six times as much.

In slow scopes I would recommend this eyepiece without reservation, but at f5 if you want stars to look sharp right across the field, I'm sorry to say that there is no alternative to spending a lot of money for a premium eyepiece.

Geoff