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N3ptune

Dobson or newtonian on a dobson mount?

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There is something not quite right..

The dobsonian telescope is it more a dobson/dobsonian or a newtonian reflector on a dobsonian mount. (Or else)

What do you think? (there seems to be some kind of conflict between who invented what)

SUzBPbN.jpg

 

Edited by N3ptune

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HI there.

A 'Dobsonian' is a Newtonian Reflector telescope mounted on a Dobsonian base, designed in the `50s by  John Dobson.

Edited by Charic
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That's 1 for dobsonian

But what about the credits for Isaac Newton? If I say a Dobsonian, i am speaking about the whole, the tube and mount. If I choose to say Dobsonian then it seems I am giving credits to John Dobson exclusively where the Newtonian telescope is becoming a Dobsonian telescope.That's where I am uncertain

 

 

Edited by N3ptune

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You can mount a newtonian telescope on any type of mount - equatorial, fork, dobsonian, alt/az, etc. A dobsonian is a specific type of mount that can handle larger newtonian telescopes. There's no reason why you can't mount a refractor on a dobsonian mount - it's just a rocker box on a turntable. :)

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Dobson devised a simple altazimuth box and not the Newtonian telescope that it carries. To call the telescope a Dobsonian is an insult to the instrument and its inventor. There is no such instrument as a Dobsonian! Dobson's claim to fame lies merely in that he knocked together a cheap and cheerful mount out of scrap, and which had appeal to ATMers. The Dobson mount is cheaply constructed and transported, and so is popular with scope manufacturers. The term Dobsonian is nothing but an americanism which has caught on!

Prior to Dobson's simple mount design Newtonian reflectors were often found mounted on altazimuth forks, many of which used slow motion controls in both axes and stood on a pier or tripod. The Dobson style mount was easier to transport and so became popular with amateurs on the move. Dobson devised a cheap, simple mount and nothing more! Newton takes credit for the telescope!

Mike

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A dobsonian is most usually a Newtonian telescope invented by Isaac Newton, on a dobsonian mount invented by John Dobson, simples :) 

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To my mind, the defining feature of the Dobsonian is the very large altitude bearings which sit on their carriers.

There are plenty of telescopes that are, in my opinion, wrongly called Dobsonians presumably to cash in on the prestige that comes from many true Dobs being quite large or very large. :mad:

In my opinion, the telescope shown above is not a Dob.

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Some people even say the large bearing truss designs should be called 'Kriegian" :)

Newton is the genius who made the most important inventive step with reflector optics imho.

Screenshot_2016-12-24-08-59-50.png

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How about calling them Newtdobs, combining the names Newton & Dobson together? ;) 

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must be the poor weather that sparks these threads :hiding:

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35 minutes ago, Knighty2112 said:

How about calling them Newtdobs, combining the names Newton & Dobson together? ;) 

Doesn't flow somehow - how about Dobtonian?

Doug.

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I most remember John Dobson for sharing the Universe with as many people as possible. I suspect thats how he would like to be remembered rather than have folks quibbling over the naming conventions of telescopes. They were just tools to achive the outreach for him.

One of his sayings went along the lines of it does not matter what scope you have, how big it is and how good it's quality is, what matters is how many other people get to look though it.

 

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To further confuse the issue, Newton didn't invent the reflecting telescope. That honour goes to Scottish mathematician James Gregory. A few years later Newton built his own telescope which improved and simplified Gregorys' design, and then got all the credit for it.

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37 minutes ago, BritAngler said:

To further confuse the issue, Newton didn't invent the reflecting telescope. That honour goes to Scottish mathematician James Gregory. A few years later Newton built his own telescope which improved and simplified Gregorys' design, and then got all the credit for it.

The Gregorian reflector was a theoretical design which was not successfully built until five years after Newton's own reflector. And there were other theoretical designs for reflectors about thirty years earlier than James Gregory's. The Newtonian was the first practical reflecting telescope.

 

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As far as I know original Dobson telescopes had small alt bearings and he made large aperture observing accessible to the masses either through freely sharing designs and ideas or allowing people to look through his scopes;  this legacy lives on today.

Whilst the Dobson mount may may not be shiny or glamorous, if well constructed, it is more stable  for it's portability than any other mount for large apertures.

I never met John Dobson but he appears to be a generous and innovative astronomer with no obvious hunger for fame..  Just because he is American doesn't negate his achievements.

As with Newton's design things have naturally moved on as people put their twist on things but In the Dobson tpeople are usually happy to pass on design tips.

The mount is the Dobsonian element the scope could be any design; both mount and scope are complimentary if you want to see anything :icon_biggrin:

images.jpeg

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Some folk in the past have asked which is better, the  Newtonian or Dobsonian, thinking there was a difference?
If someone is buying a Dobsonian, its  in reference to the type of mount that the scope is fitted too, but as Brantuk mentions, its possible to attach any scope to a Dobsonian mount with a little forethought,  and a Dobsonian, with its cheaper,  simple to operate mount makes for  a cheaper option, for example,  take the Sky-watcher Explorer and Skyliner, both have 200mm  8" apertures, but you'll pay more for the scope with the EQ system!  ( EQ £469  Dobsonian £285 )

Edited by Charic
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7 hours ago, Stu said:

A dobsonian is most usually a Newtonian telescope invented by Isaac Newton, on a dobsonian mount invented by John Dobson, simples :) 

Nice one Stu, made me smile :happy11:

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John Dobson himself called it a "sidewalk telescope" not a Dobsonian ;) 

 

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I am starting to understand the meaning of Dob mob right now.

:happy6:

Edited by N3ptune
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If we are to be factual about this, the late John Dobson didn't  invent the alt-az mount that currently carries his name. There are several instances of the design pre-Dobson. What John Dobson did, to his credit, was to apply it to large Newtonian telescopes and popularise its use though his and others "Sidewalk" astronomy, his association and the use of his name is well deserved. I had the pleasure of meeting John in San Francisco in 1989 and the UK in 2002.  :icon_biggrin:

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Whatever they are called....still better than a Frac....:hiding:

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