Just supposing I was in the market for a little refractor...

[Ian]

APO or Petzval?

APO - best colour correction, Petzval flat field, cheaper but not quite so well corrected.

or is the key question, what have you got in stock?

[Mike]

Petzval?! Never even heard of it !!

[Rocket Pooch]

What ever you get ensure your happy, my zs66 is still in the box and has only ever been used once, and I happy, yes.

Interestingly I have meet someone with one of the newer skywatcher equinox scopes, he was not impressed with the field curvature and the zs66 has the same issue as well.  So how about, dare i say it an ed80?  Sorry predictable answer.