Newtonian, dobsonian is it just the mount

[poider]

Gday, Just wondering about the difference between a Newtonian Reflector and a dobsonian.
Is a Dobsonian just a Newtonian reflector on a different mount, if you take a Dobsonian tube and place it on an equatorial mount does it become a Newtonian reflector or is it a dobsonian on an equatorial mount.
If I take my 6 inch Newtonian Reflector and place it on a wooden rotating base doe sit then become a Dobsonian?
Is there a really good website that explains in simplistic terms exactly what each telescope has as advantages and disadvantages, and describes exactly why lenses and telescopes are made the way they are?
I know that a reflector has collimation problems and a refractor has chromatic abberation problems but what about dobs and cassegrains etc???
Peter

[raymo]

The tube assembly is a Newtonian regardless of what type of mount it is on.
The term Dobsonian came into being when an American called John Dobson
put Newts onto the very simple alt/az mount that now bears his name, in
order to make cheap scopes that he and his colleagues called "The Sidewalk
Astronomers" took around the city streets to try and get the general public
into Astronomy.
raymo

[poider]

thank you Raymo, I was on the right track
what about cassegrains?
Peter

[billdan]

Hi Peter,

Cassegrains and the different variations ( SCT, Ritchey Chretian, Gregorian, Dall Kirkham etc) are all reflectors that fold back the light cone so it focuses behind a hole in the primary mirror.

However the secondary mirror cannot be a flat mirror, it must have some magnification or else the focal point would never make it past the primary.

Like Newtonian's they also have to be collimated to perform correctly.

Cheers
Bill

[Wavytone]

Hi Peter, there's a book you might find interesting "Unusual Telescopes" by Peter Manly.