Astronomy

What is a Good Dobsonian Telescope



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"What is a Good Dobsonian Telescope"
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Ever since I can remember I have been passionate about space, although I despised science at school. Perhaps it's the English Literature student in me who is drawn to the romantic, the unobtainable beauty of the cosmos.
Let's start with some stuff that might be useful to anyone considering buying this scope before going on to what everyone always asks when discussing telescopes, what can you see?

Firstly this telescope is a Dobsonian, this refers to the base on which the actual tube is mounted. The mount is a simple wooden structure made from cheap wood, it rotates 360 degrees and is the easiest of all mounts to operate. The actual telescope is of Newtonian design, it is a reflector. Reflecting telescopes have a large primary mirror which bounces light onto a smaller secondary mirror whose job it is to reflect the light into the ultimate optical system, your eye! To keep from getting boring I won't go into extreme detail (as it can get a little dull) instead I'll do some pros and cons of the Dobsonian that a potential buyer will want to know:

Pros
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-Cheapest telescope per inch of aperture (Width of mirror)
-Easy to operate (No polar aligning that is synonymous with equatorial mounts)

Cons
-

-Big (unless you buy collapsible Dob which comes with its own set of pros and cons)
-Bigger sizes are hard to transport
-No tracking (cannot follow objects through the sky as easily as equatorial mounts)
-The cheaper Dobsonians can be stiff (mine is) and therefore jerky, this can be incredibly frustrating when trying to follow deep space objects (DSO'S)
-Does require regular collimation (adjustment of the primary and secondary mirrors to ensure the telescope operates at full function)


Now, I know that the Cons outnumber the Pros but my own personal opinion is that a Dobsonian makes a brilliant telescope. It is true that the stiffness in moving the scope is at times incredibly frustrating, but this is more than made up for in size of mirror, enabling you to see much deeper into space.

This particular model is one of the cheaper Dobsonaians available, with a 12 inch (300mm) mirror it set me back £600, If I had the money I would have gone for a light bridge made by Meade, but alas I am poor so the Sky-watcher was the clear choice.

This particular scope is ideal for getting the most aperture for the least amount of money.

Now onto the interesting bit, what can you see? For reference I am in a fairly light polluted suburb of London, bortle class 7, with a NELM of 4.8 towards the south east of the zenith, for those who don't speak nerd that just means my skies are pretty bright but could be worse.


Here are a handful of the best of the hundreds of objects I have observed with my trusty Sky-watcher.

-the beautifully bright nucleus of the Andromeda galaxy (our closest galactic neighbour at around 2.9 million light years, one light year is very roughly six thousand billion miles) just for fun, that makes the galaxy this many miles away....17,400,000,000,000,000,000

-the satellite galaxies of Andromeda, m32 and m110. These smaller galaxies are bound by Andromeda's gravitational pull.

-the marvellous galaxy pairs of m65, m66 and m81,m82. These are galaxies that are so close to eachother that they appear in the same field of view.

-NGC 5194 and NGC 5195 (also known as M51, the whirlpool galaxy). These are two galaxies that are in the process of smashing together and coalescing.

-M13 and M3. These are globular clusters, thousands upon thousands of stars, condensed down into an area of space that appears about a third the size of the full moon (although in reality the clusters are much bigger than this, just much further away on the fringes of our galaxy). Globular clusters are arguably the most beautiful objects in the sky. Think of spilling a large handful of tiny diamonds onto a black velvety cloth.

-M57 (The ring nebula) is the remnants of an exploded star known as a planetary nebula. The name is misleading as they've nothing to do with planets except early astronomers thought they looked like planets. In my sky-watcher you see a little smoky ring of bright mist with a clear darkening towards the center. Planetary nebula can be very pleasing with m57 being perhaps my favourite of the more well known PN's. Aesthetically M57 is beautiful, but sometimes the joy of looking through a telescope comes from the sheer distance of what you're looking at, subjects like IC351 and IC2003.

I have observed around 100 object which would take forever to go into, if I could get my scope to darker skies then many more hundreds of objects would become visible as well as becoming more defined. But even if you live in pretty light polluted skies like me, with a bit of patience, the Sky-watcher 300 parabolic dobsonian will show many, many deep sky treats as well as provide wonderful views of the moon, planets of the solar system and even distant moons such as the wonderful orange hue of Saturn's Titan (the only moon in the solar system to have a substantial atmosphere).

In conclusion, optically this scope will enable you to see many stuning objects, the down side being the frustration that can sometimes arise when the telescope is too stiff to move gently and precisely. If you want the biggest aperture for £600, this scope is the clear choice.


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