Why do people recommend the Dobsonian? Let me explain because I think it may not be clear.
There are 3 parts to the thing we call a telescope.
- The optical tube assembly, OTA which is the part that gathers the light. Typically this is a Newtonian reflector, a refractor or a catadioptic (SCT, Mak or other) which is a combination of reflector and lenses.
- The eyepiece, the part that focuses and magnifies the image
- The mount which holds the OTA.
When we talk about a Dobsonian we are not talking about the OTA, we are talking about the mount that was developed by
John Dobson . It is an altAz type mount that sits on the ground on a turntable. It is inexpensive to make and very stable. Those two characteristics are what make it so popular.
The fact that most, but not all dobsonian systems are based on the Newtonian OTA can lead people to think that Dobsonian means a Newtonian telescope, but that is incorrect.
You can find refractors on Dobsonian mounts too. These are mostly table top units, but they share the same benefit of being very stable and inexpensive because the mount is cheap to make but very stable. And there is no reason you could not put an SCT or a Mak on a dob mount.
One of the downfalls of inexpensive telescope systems is that the mounts are weak or overloaded, to keep the cost down. They wobble and shake and don't aim well because of it. So you put a very good OTA on a poor mount and you have a bad telescope. Often this is the issue with the "department store" telescopes.
A common Dob might consist of an 8" 1200 mm FL Newtonian OTA weighing 20 pounds/9 Kg. This is a great OTA and can be put on a dobsonian base fairly inexpensively. Put that same OTA on a tripod mount of similar stability and the cost could double. Same OTA but different mount.
The OTA that you are looking at is a 750 mm reflector. Why the shorter FL? Partly because putting a 1200 mm reflector on a tripod altaz or equatorial or even a GoTo would mean that that mount would need to handle a lot more weight and therefore be much more expensive.
There are optical and physical reasons one might want to work with a shorter FL Newtonian but the fact that a 750 is lighter than a 1200 is certainly part of the reason.
I hope that helps.
So, as you decide what you want as your first telescope I would suggest the following points of consideration.
- Where will you store it and how will you move it to the observation location? If it is too much trouble to set-up you won't use it.
- How much weight can you comfortably handle? I selected my 8" Dob at 42 pound vs. a 10" at 60 pounds strictly based on the weight and I am very pleased with my decision.
- What are you light pollution conditions? Will you be able to view from home or will you need to load your scope in the car to use it? How big is your car?
- How will you find your targets? Are you looking forward to working with charts and such to plan out star hops or will you want a Goto or a Pushto system? Do you use a GPS in the car or do you plan out your trips with paper maps?
- What do you want to see? Everything of course!
- What is your budget? Discussing telescopes without a budget in mind is useless. What constitutes a beginner scope is driven by budget, not technology.
After you answer these, then look at the technologies that will give you what you want within the budget you can afford. You can get a lot more aperture for your dollar on a dobsonian mount than any other mount and that is why they are so popular. But that might not be the right choice for you.
That is how I approach these things and how I recommend you approach it. Telling you to get an 8" dob without knowing the answer to these questions is a disservice to you. I have an 8" Dob, but it was not my first telescope. My first scope was an 80 mm refractor on a Goto mount. And my 8" Dob is also computer assisted.
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