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Thanks for stopping by. I hope you find the experience worthwhile. This blog post has been written from my own 'beginner perspective' after doing lots of reading on the topic below. In getting my head around it all, I may have got odd bits slightly wrong; but, like you, I am on a leaning journey, so please forgive any unintentional errors. Meanwhile, clear skies to you. Take care and thanks for visiting Steve aka PlymouthAstroBoy
Today’s post: a
beginners guide to telescope mounts.
If, as a beginner to astronomy, you are thinking of buying
your first telescope then you might find it useful to read these blog posts
first:
Done your research? Got some ideas about what type of
telescope you might want to get? Then your next decision is to consider what
mount to support it on.
One of the first things I learned from local astronomers and
astrophotographers was that the choice of mount is one of the most crucial
decisions you will make in assembling your astronomy/astrophotography rig.
“How so?” I hear you all ask.
Well, point your new telescope to your chosen deep sky object
spot in the sky and you will be wanting it to track this object smoothly. The tripod
and mount head will help determine ‘how smooth’ this tracking will be!! At high
magnifications every wobble, every wiggle, every vibration is amplified
immensely; so much so that your object becomes almost completely unviewable. Remember
a deep sky object will be moving very fast above you – well it isn’t – it’s the
earth’s rotation below your feet – that makes it LOOK as if the DSO is rotating
(when in fact it isn’t). try keeping that DSO centred in the field of view of
your eyepiece when the slightest touch causes it to go into a mass meltdown
vibration!! Remember, depending on the mount type you purchase, you may need to
be fine tuning adjustment knobs and wheels frequently in very small amounts! Can
you imagine the frustration experienced if the telescope then takes a minute or
two to return to non-movement after an adjustment – by which time your DSO has
moved out of view once more! Eek!
So – rock solid tripod. Rock solid mount!
Fortunately, if you are buying your equipment from a
reputable dealer, it is likely that your chosen telescope will come as a
package – with an appropriate mount and tripod included. Note the emphasis here
on ‘reputable dealer’!
So, lets talk an overview of mounts! Typically there
are four types – Dobsonian, Alt Azimuth, Equatorial and Computerised.
Each have advantages and disadvantages as you would expect.
Alt-Azimuth
A mount type which allows a telescope to move up -down and
left-right. It is the oldest and simplest mount design to manually adjust and they
require very little set up. Great for small telescopes because the mount is
small, light and compact. Many have slow motion controls to change the
telescopes altitude (up/down) and azimuth (left/right) position. Cheap, quick
set up, easy to master – remember that these mounts require more adjustments to
track objects. The wooden based Dobsonian telescopes are a type of “alt-Az”
mount. They too are easy to use and reasonably priced; easy to transport
(because they can be split into two parts) and are based on Newtonian telescope
optics. Not so great for astrophotography I am told.
Remember – the Azimuth, the mount spins horizontally
clockwise and anticlockwise in a full 360 degree circle.
And, Altitude – the mount allows your telescope to be
elevated in the vertical towards an upright position from horizontal (0
degrees) to vertical (90 degrees)
One last point – you can get alt-az mounts as GOTO – single arm
mounts with ports for connecting a GOTO hand controller and external power
supply. Some will have AA battery compartments as well. Some can even be controlled
wirelessly from your mobile smartphone using an app. See below for further
points about computerised GOTO systems. (Some manufacturers produce equatorial
wedges for their Altaz mounts which turn them into equatorial mounts (see
below) and some mounts are dual fork mounts where a larger aperture telescope
is supported between two arms, thereby spreading the weight of the tube more
evenly between them).
Some further reading: https://www.skyatnightmagazine.com/advice/skills/get-to-grips-with-altaz-mounts
Equatorial Mounts
These mounts track deep sky objects by turning on one axis –
the polar or RA axis which is parallel to the Earth’s rotational axis (and
therefore aligned to the rotation of the celestial sphere). The telescope can
then track the apparent movement of the stars across the ‘celestial sphere’
night sky in an arc following the rotation of the sky.
Celestron Advanced VX (AVX) telescope mount
Image copyright: Rother Valley Optics
EQ mounts are very popular. Why?
Because astronomers need to track a deep sky object and keep
it within the eyepiece field of view, then they need to rotate the polar axis
at the same rate as the earth rotates – manually or by using a motor driven
mount.
A good overview of how to set up an EQ mount can be found
here https://www.skyatnightmagazine.com/advice/equatorial-mounts-an-astronomers-guide/
Computerised mounts
These mounts are very expensive but probably once set up,
the easiest to use. Marmite mounts – loved and hated equally I suspect! Computerised
GOTO mounts have small motors and use a keypad and/or app to control the
tracking. They require a simple alignment process on three of the brightest
stars in the sky. And once done, the mount will track and locate any deep space
object in the database. Some say they are game changers! A big time saver when
it comes to setting up for the evening. You don’t need any prior ‘star’ knowledge;
objects are tracked for you and they are absolutely fantastic if you wish to
delve into astrophotography. They are very good for quickly locating very faint
deep space objects (which normally take considerable skill and practice to
locate).
Downsides? Collimation, expense, weight, having to do the
alignment procedure at the start of every session, and of course, they need a
robust power station to power them.
Some further reading on GOTO mounts? https://www.skyatnightmagazine.com/advice/go-to-telescope-mounts
A final emphasis then – whatever mount you choose - a stable
smoothly moving tracking mount is essential for a good observing or
astrophotography experience. No vibrations or wiggles for minutes after you touch
it doing adjustments!
So, a summary guide - as a beginner new to astronomy, "how should
you go about choosing a mount for your new telescope?"
1.
Go to a reputable dealer and seek their advice, and
2.
find a local astronomy club and see if they have
a public liaison officer who can offer advice as well
3.
If you buy your telescope from a good dealer it
will normally come packaged with a mount and a tripod; if it doesn’t, a good
dealer will recommend a series of appropriate mounts and tripods for the
telescope you have bought
4.
The kind of observing and celestial objects you
wish to view may help you decide on an appropriate mount. If you aim to do
mainly visualisation of faint objects, go for a simple, less expensive mount
design (such as an Altaz or Dobsonian) and save the money for better quality
optics.
5.
Think about how portable you need your mount to
be - the bigger and heavier the mount, the more difficult it will be to get it
to a viewing site
6.
Similarly, try to think ahead as to what your
requirements might be in the future. Can the mount be adapted for
astrophotography? If you buy a new telescope in the future, will it fit the
mount you have?
Further reading: https://www.skyatnightmagazine.com/advice/a-basic-guide-to-telescope-mounts and https://astroforumspace.com/best-beginner-telescope-mounts-for-astrophotography/
Footnote: As is the case for all websites and any suppliers or equipment manufacturers I mention - I am not gaining in anyway - not financially, not in gaining page views, not in gaining equipment to test. Nothing! I do not blog to gain in any way.
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