You are right Jon,

I stil have two others Newton scopes. A 12,5 inches Dob and a 8 inches EQ. The
two are at F6. I want a scope for widefield at low power and perhaps
terrestrial viewing. I think that Orion (or Skywatcher) 120 F5 wil be the berst
for me.


Jon Isaacs wrote:

An important issue here is what does one want to do with the scope and how does
it fit in with ones other scopes.

Orions 80mm ED refractor is certainly a nice scope but it is 600mm FL and a 24
inch scope. The 100mm F6 and the 120mm F5 scopes are about the same length and
yet provide significanly more aperture. So if one already has a scope which is
better suited for higher power work, then it maybe that the short focal length
Achromats were chosen for widefield work where the aperture is more important
than the color correction.

Given the focal ratio of the 80ED, if Orion does comeout with 100mm, 120mm and
150 mm ED refractors and assuming the same glass, they will need to be slower
focal ratio which will make the tubes quite long.

Having owned the 120mm F8.3 scope for a year or so, I know that the 40 inch OTA
is quite a different bird than a 20 or 24 inch tube of a faster 100mm scope.

Lots of variables to consider....

jon