Equatorial Mount

I've been stargazing for not quite a year and have a small reflector on
an equatorial mount. In the next few months I am thinking of upgrading
to a larger scope (6" or 8", most likely the 8"). With that decision,
obviously comes the choice of a mount.

I've only used a dobsonian mount once, and really didn't care for it too
much. I think my primary complaint was having to manually slew the
scope while tracking versus using the slow motion dials on my current
mount.

So I'm leaning toward another equatorial mount, but have one question
that I've never come across an answer for. With the equatorial, the
scope ends up in some odd positions and I find myself untightening the
ring clamps and rotating the tube so the eyepiece is in a usable
location. This just seems wrong that I have to do this. On my small
(4.5") telescope it is no problem but with a much larger tube I see this
being a more difficult maneuver. Am I doing something completely wrong
with my current mount/tripod? Should I never find myself rotating the
tube to get a better position for the eyepiece?

Please advise!

EJ

In the next few months I am thinking of upgrading
to a larger scope (6" or 8", most likely the 8")...
I've only used a dobsonian mount once, and really didn't care for it too
much.
I'm leaning toward another equatorial mount.
With the equatorial, the
scope ends up in some odd positions and I find myself untightening the
ring clamps and rotating the tube so the eyepiece is in a usable
location. This just seems wrong that I have to do this...

Consider a fork-mount (EQ) SCT.
No counterweights, no tube rotations, no gymnastic
observing positions.
Observe seated comfortably, east to west, horizon
to zenith.

SSX

SaberScorpX wrote:
Consider a fork-mount (EQ) SCT.
No counterweights, no tube rotations, no gymnastic
observing positions.
Observe seated comfortably, east to west, horizon
to zenith.

Except the pole. It's not so much observing there as it is finding
targets there with a finder (either optical or Telrad).

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Consider a fork-mount (EQ) SCT.
No counterweights, no tube rotations, no gymnastic
observing positions.
Observe seated comfortably, east to west, horizon
to zenith.

Except the pole. It's not so much observing there as it is finding
targets there with a finder (either optical or Telrad).

In those rare cases (near the pole), I sometimes simply lift the
whole scope and rotate the tripod 180 deg. (AltAz mode, no tracking.)
No biggie for casual observing.

SSX

On 22 Nov 2004 02:34:11 GMT, (SaberScorpX) wrote:

Consider a fork-mount (EQ) SCT.
No counterweights, no tube rotations, no gymnastic
observing positions.
Observe seated comfortably, east to west, horizon
to zenith.

Well, I'm a big fan of fork mounts, and SCTs. But with any equatorial mount,
including forks, you get tube rotation. Maybe you mean that it is easy to rotate
the diagonal of an SCT to compensate? And your definition of "gymnastic" may be
different from my own, but I find that there are positions that are darned
awkward, especially near the pole where the EP and fork base are close. And of
course, any equatorial mount is tricky to use near the pole since it can require
huge rotations for tiny movement (although the same problem exists with altaz
mounts near the zenith, and I think that is far worse).

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Consider a fork-mount (EQ) SCT.
No counterweights, no tube rotations, no gymnastic
observing positions.
Observe seated comfortably, east to west, horizon
to zenith.

Well, I'm a big fan of fork mounts, and SCTs. But with any equatorial mount,
including forks, you get tube rotation. Maybe you mean that it is easy to
rotate
the diagonal of an SCT to compensate?

Very good, cloudbait. That's just what I meant.

I find that there are positions that are darned
awkward, especially near the pole where the EP and fork base are close.

Try spinning the tripod. It takes 5 seconds.
For starhopping and casual observing, polar-alignment is not
written in stone.

SSX

On 22 Nov 2004 07:04:45 GMT, (SaberScorpX) wrote:

Try spinning the tripod. It takes 5 seconds.
For starhopping and casual observing, polar-alignment is not
written in stone.

Personally, I would consider spinning the polar axis of the scope to a direction
other than north to be crazy. We are talking about equatorial mounts here, and
if you aim an equatorial mount someplace other than north, the movements of the
axes become really confusing. Eric's original post suggests that he is using a
tracking mount, and that is not going to work if you rotate it away from north.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Eric Johnson wrote:
[ ... ]

So I'm leaning toward another equatorial mount, but have one question
that I've never come across an answer for. With the equatorial, the
scope ends up in some odd positions and I find myself untightening the
ring clamps and rotating the tube so the eyepiece is in a usable
location. This just seems wrong that I have to do this. On my small
(4.5") telescope it is no problem but with a much larger tube I see this
being a more difficult maneuver. Am I doing something completely wrong
with my current mount/tripod? Should I never find myself rotating the
tube to get a better position for the eyepiece?

Please advise!

EJ

Hello Eric,

Regarding the tube rotation - I have an 8" on EQ mount and it is not
difficult to rotate the tube. I was thinking initially to get some kind
of rotating rings, but now I do it automatically and don't even think
about it. The tube is not heavy, clamps (at least on my scope) are
pretty easy to operate, and I found that balance is usually not an issue
after rotating the tube.

Regards,

- Alex

Fantastic, thank you for this input. I'm also glad to hear that having
to rotate the tube is a normal thing.

Thanks again!
Eric

Alexander Avtanski wrote:

Eric Johnson wrote:

[ ... ]

So I'm leaning toward another equatorial mount, but have one question
that I've never come across an answer for. With the equatorial, the
scope ends up in some odd positions and I find myself untightening the
ring clamps and rotating the tube so the eyepiece is in a usable
location. This just seems wrong that I have to do this. On my small
(4.5") telescope it is no problem but with a much larger tube I see
this being a more difficult maneuver. Am I doing something completely
wrong with my current mount/tripod? Should I never find myself
rotating the tube to get a better position for the eyepiece?

Please advise!

EJ


Hello Eric,

Regarding the tube rotation - I have an 8" on EQ mount and it is not
difficult to rotate the tube. I was thinking initially to get some kind
of rotating rings, but now I do it automatically and don't even think
about it. The tube is not heavy, clamps (at least on my scope) are
pretty easy to operate, and I found that balance is usually not an issue
after rotating the tube.

Regards,

- Alex

Eric Johnson wrote:

Fantastic, thank you for this input. I'm also glad to hear that having
to rotate the tube is a normal thing.

It's very helpful (and easy) to put some kind of retaining ring (such
as an embroidery hoop) on the tube. When you loosen the tube rings it
will prevent the tube from sliding down as you rotate it and upsetting
the balance of your set up. Saves a lot of time when you set up too -
always gets the tube rings in exactly the same place on the rings.

-----------------------------
Martin Frey
http://www.hadastro.org.uk
N 51 01 52.2 E 0 47 21.1
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