Determining if Parabolic or Sperical mirror

[Astro78]

Hi Guys,

Just looking at a few 2nd hand Newts and wondering if there was an easy way to tell if they have a parabolic or spherical mirror?

Would prefer parabolic but some of these scopes are older than 5 years and their owners genuinely don't know...

Trav
:)

[Starkler]

Cheap newts of f8 or slower are very likely to be spherical as it doesnt matter as much as it does for faster newts.

There is a Synta made 130mm f7 newt which is known to be spherical and I would avoid that one. Cheap unknown brands I would avoid like the plague unless given the opportunity to test under the stars.

Apart from researching online, the only other practical way would be a star test.