Johnsonian Telescope???

Has anyone in this news group tried one of those Johnsonian pop-up
telescopes? They look great for travel but I was not sure if there would be
another downside.
I.e.
How stable they are. With the flexible carbon-fibre braces do they tend to
move with a slight wind or ground shaking or they as table as any other
scope?

Secondly does one have to collimate each time you get them out since the
secondary mirror is not held in position relative to the primary when
compressed down to their little bucket for travel?

thanks


Chameleon

Actually, you need to plan on re-collimating any dobsonian when you
reassemble it. In the case of the Johnsonian(15"/18"/22"), collimation
of the primary is achieved at the eyepiece using the motors on the back
of the primary. As far as I know, that's a first for amateur
telescopes.

Dennis Dickerson

Yes, the Johnsonian designs seem to be very innovative. I doubt I could come
up with the funds for one of the larger scopes you mentioned but for the
price the 10" or 12" are very enticing.


Chameleon


wrote in message
oups.com...
Actually, you need to plan on re-collimating any dobsonian when you
reassemble it. In the case of the Johnsonian(15"/18"/22"), collimation
of the primary is achieved at the eyepiece using the motors on the back
of the primary. As far as I know, that's a first for amateur
telescopes.

Dennis Dickerson