Help! Vibrating Telescope!

I'm going to assume you weren't attempting to observe in windy
conditions, nor using an absurd amount of magnification.

Most of the cheaper scopes suffer from serious damping problems and even
quite expensive scopes like the larger Meade and Celestron STC's are not
what I'd call well damped.

The damping problems are normally caused by spindly shafts that are too
lightweight to provide the level of rigidity and damping required. There
are other gremlins that lightweight mounts frequently suffer from that
add to the problem such as cheap and cruddy bearings, mechanical slop,
insufficient mechanical rigidity etc.

It's worth making up what's known as a rock sling, which is a bag that
fits between the tripod legs and is filled with rocks or other weighty
mateial such as lead. Don't use too much weight or the tripod will
collapse! I'd suggest 5-10 pounds or so to start. See if that helps. If
it doesn't then you'll need to find a better mount for the scope.




In article ,
lid says...


Greets,

I just got a secondhand Meade Polaris 3" reflector, complete with tripod.
After a few hours of restoration (missing screws, collimation, broken
reticle crosshair in the finder scope...), I tried it out tonight.

I _think_ I was looking at Arcturus; I live in Pensacola, FL, and the
star was high in the west-northwest (RA 14h 17', Dec 18d 39' according to
SkyGlobe).

It was the most aggravating bit of stargazing I've ever done, because the
scope vibrates if you so much as look at it. Turn the focus knob and it
takes 20 seconds to settle down enough to be useful.

Is there a way of damping the thing down? I don't have much use for a
scope that is going to show me live-action star trails instead of a point
of light. ;p

Ian W wrote

It's worth making up what's known as a rock sling, which is a bag that
fits between the tripod legs and is filled with rocks or other weighty
mateial such as lead. Don't use too much weight or the tripod will
collapse! I'd suggest 5-10 pounds or so to start. See if that helps.
If it doesn't then you'll need to find a better mount for the scope.



He could also try to put special rubber dampening tabs under the tripod
legs

--
CeeBee


Google CeeBee @ www.geocities.com/ceebee_2

On Sun, 27 Jul 2003 04:13:50 +0800, Ian W
typed:

It's worth making up what's known as a rock sling, which is a bag that
fits between the tripod legs and is filled with rocks or other weighty
mateial such as lead. Don't use too much weight or the tripod will
collapse! I'd suggest 5-10 pounds or so to start. See if that helps. If
it doesn't then you'll need to find a better mount for the scope.

I use a jug of water for my el cheapo no name scope.
--
All viruses and spams are automatically removed by my ISP before
reaching my inbox.

Ian W wrote in
:

I'm going to assume you weren't attempting to observe in windy
conditions, nor using an absurd amount of magnification.

Dead calm, standard 25mm (28x) eyepiece.


Most of the cheaper scopes suffer from serious damping problems and
even quite expensive scopes like the larger Meade and Celestron STC's
are not what I'd call well damped.

This one sucks, to put it plainly. I've got a 6" reflector on a cheap
camera tripod that hardly oscillates at all. The Meade's got an utterly
strange support rail/altitude/traverse mount.

The damping problems are normally caused by spindly shafts that are
too lightweight to provide the level of rigidity and damping required.
There are other gremlins that lightweight mounts frequently suffer
from that add to the problem such as cheap and cruddy bearings,
mechanical slop, insufficient mechanical rigidity etc.

Sloppy. Yes, I'd use that term...I'm thinking that the rubber "pinch"
washers that are supposed to hold the scope at a given altitude angle
doesn't help this at all. It seems that most or all of the oscillation is
happening above the traversing (left/right direction) pivot.

It's worth making up what's known as a rock sling, which is a bag that
fits between the tripod legs and is filled with rocks or other weighty
mateial such as lead. Don't use too much weight or the tripod will
collapse! I'd suggest 5-10 pounds or so to start. See if that helps.
If it doesn't then you'll need to find a better mount for the scope.

Cool; thanks for the idea! I'll give it a shot if replacing those rubber
washers doesn't do anything.

--
J W

*sig has expired. Go to alt.hacker and ask for a crack for it.*

I knwo my answer s tacky, but I figure you just need a better mount

"J W" wrote in message
.. .


Greets,

I just got a secondhand Meade Polaris 3" reflector, complete with
tripod.
After a few hours of restoration (missing screws, collimation, broken
reticle crosshair in the finder scope...), I tried it out tonight.

I _think_ I was looking at Arcturus; I live in Pensacola, FL, and the
star was high in the west-northwest (RA 14h 17', Dec 18d 39' according to
SkyGlobe).

It was the most aggravating bit of stargazing I've ever done, because
the
scope vibrates if you so much as look at it. Turn the focus knob and it
takes 20 seconds to settle down enough to be useful.

Is there a way of damping the thing down? I don't have much use for a
scope that is going to show me live-action star trails instead of a point
of light. ;p

--
J W

*sig has expired. Go to alt.hacker and ask for a crack for it.*

I know my answer is tacky, but I figure you just need a better, sturdier
mount for your scope Maybe you should try to replace your tripod with a
heavier one?

"J W" wrote in message
.. .


Greets,

I just got a secondhand Meade Polaris 3" reflector, complete with
tripod.
After a few hours of restoration (missing screws, collimation, broken
reticle crosshair in the finder scope...), I tried it out tonight.

I _think_ I was looking at Arcturus; I live in Pensacola, FL, and the
star was high in the west-northwest (RA 14h 17', Dec 18d 39' according to
SkyGlobe).

It was the most aggravating bit of stargazing I've ever done, because
the
scope vibrates if you so much as look at it. Turn the focus knob and it
takes 20 seconds to settle down enough to be useful.

Is there a way of damping the thing down? I don't have much use for a
scope that is going to show me live-action star trails instead of a point
of light. ;p

--
J W

*sig has expired. Go to alt.hacker and ask for a crack for it.*

Ian W wrote in
:

In article ,
lid says...
Ian W wrote in
:

I'm going to assume you weren't attempting to observe in windy
conditions, nor using an absurd amount of magnification.

Dead calm, standard 25mm (28x) eyepiece.

That's bad, real bad!

This one sucks, to put it plainly. I've got a 6" reflector on a cheap
camera tripod that hardly oscillates at all. The Meade's got an
utterly strange support rail/altitude/traverse mount.

It may not be a Meade design. Most of the commercial scope
manufacturers are sourcing their cheaper and smaller scopes out of
China and that is a lottery, one factory makes a good mount, another a
junker. If it is a Meade designed mount then it's yet another example
of Meade building to a price. I've owned a couple of Meade and
Celestron scopes and both had major flaws in their mount designs.

It's got POLARIS *by Meade* on the side...maybe it's a Chinese knock-off
*g*


Sloppy. Yes, I'd use that term...I'm thinking that the rubber "pinch"
washers that are supposed to hold the scope at a given altitude angle
doesn't help this at all. It seems that most or all of the
oscillation is happening above the traversing (left/right direction)
pivot.

I see wobble wobble wobble, rubber in a scope mount .. blech! I've not
seen the mount so really can't comment but perhaps stainless steel
split washers are worth considering as viable replacements for the
rubber rubbish.

The only reason I can see for having a sloppy rubber-washer "pinch" on the
thing is that the elevating shaft only acts as a pivot, with no provision
to lock it down. The elevation lock-down mechanism is in the form of a
poorly-positioned steering handle (twist it counterclockwise, point the
scope, then twist it clockwise to *cough* lock it.

Stupid handle is placed directly on the back of the scope mount right where
it will interfere with the tripod at high angles...and where the scope body
interferes with it.

I can tighten up and isolate the mount--no problem fabricating stuff like
that myself. OR...I'll just throw it on the camera tripod. THAT tripod has
full motion, full lock-downs, liquid-damped motion, etc. It wasn't the most
expensive one at Radio Shack, but it's been nothing but good even with some
mechanical problems in the legs.

--
J W

*sig has expired. Go to alt.hacker and ask for a crack for it.*

J W wrote:

How would Monty Python sell this thing?

Maybe something like "New, Improved VibraPod! The latest craze,
destined to replace the kaleidoscope and the Lava Lamp in every
household! Be the first in your neighbourhood with permanent double-night-vision!"

--
Odysseus

In article ,
lid says...
Ian W wrote in
:

In article ,
lid says...
Ian W wrote in
:

It's got POLARIS *by Meade* on the side...maybe it's a Chinese knock-off
*g*

Ahh one of those godawful mounts .. even the big Polaris mounts are
pretty marginal if you ask me. Then again I come from the old school of
mount makers... ie: if it doesn't weigh 100 pounds it's not solid g

Indeed the smaller Polaris mounts are made in China, not that there's
anything wrong with being made in China as I've seen some first rate
goods from there.

The only reason I can see for having a sloppy rubber-washer "pinch" on the
thing is that the elevating shaft only acts as a pivot, with no provision
snip
I can tighten up and isolate the mount--no problem fabricating stuff like
that myself. OR...I'll just throw it on the camera tripod. THAT tripod has
full motion, full lock-downs, liquid-damped motion, etc. It wasn't the most
expensive one at Radio Shack, but it's been nothing but good even with some
mechanical problems in the legs.

It sounds like you have a nice video head there. Have you considered
building your own replacement head for the mount?

Ian W wrote in
:

In article ,
lid says...

I can tighten up and isolate the mount--no problem fabricating stuff
like that myself. OR...I'll just throw it on the camera tripod. THAT
tripod has full motion, full lock-downs, liquid-damped motion, etc.
It wasn't the most expensive one at Radio Shack, but it's been
nothing but good even with some mechanical problems in the legs.

It sounds like you have a nice video head there. Have you considered
building your own replacement head for the mount?

I'm going to have to; there's just too much about the Polaris tripod I
don't like...and I'm too much like my grandfather (he was the town fix-it
man in the '30s and '40s--there wasn't a lot he couldn't fix or make) to
just leave it alone.


--
J W

*sig has expired. Go to alt.hacker and ask for a crack for it.*