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How Do You Balance Your Small Refractor for Heavy Eyepieces?

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#26 Sarkikos

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Posted 04 November 2019 - 02:57 PM

Probably too heavy for my purposes.

 

Mike



#27 makeitso

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Posted 04 November 2019 - 03:22 PM

How much weight do you need if 1.75 pounds is too much?

 

Jack



#28 clearwaterdave

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Posted 04 November 2019 - 05:14 PM

You have ignored the best solution.,ankle weights.,they worked perfect on my Omni 102 f/6.5.,and you can choose your favorite color.,cheers.,


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#29 gwlee

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Posted 04 November 2019 - 05:38 PM

A longer dovetaill won't make any difference, because I can only position the refractor so far foward on the dovetail before the focuser knobs hit the end of the dovetail.

 

Mike

Mike,

 

I put a longer dovetail (8” generic vixen from Astronomics) on my AT72ED2 to get it to balance with a 35mm Panoptic, and I must rotate the focuser a few degrees, so the focuser knobs clear the longer dovetail. It works perfectly, but looks a little odd to me because the knobs are no longer parallel with the horizon. I have set up mine, so the right knob with the fine focus mechanism is a touch higher than the left. 

 

gary

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Edited by gwlee, 04 November 2019 - 07:38 PM.

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#30 IMB

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Posted 04 November 2019 - 06:52 PM

I'm especially interested in improving the balance for my AT72EDII.  At this time it's on an AT 7" dovetail.  https://www.astronom...unts-black.html  At the end of the dovetail is a 1/4"-20 threaded hole.  Before that is a 6.9mm unthreaded hole.  One possibility I'm looking at is to attach a small counter weight to one of these holes.

 

Mike

Consider a geared head like Manfrotto 410. You'll never worry again about balancing issues.

 

med_gallery_264243_7874_1926161.jpg


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#31 Jon Isaacs

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Posted 04 November 2019 - 07:23 PM

Consider a geared head like Manfrotto 410. You'll never worry again about balancing issues.

 

med_gallery_264243_7874_1926161.jpg

 

I use Alt-Az mounts with slow motion controls. I push the forward so it's nose heavy but not quite nose heavy enough to over come the friction. I use some friction, just like a Dob, some friction is desirable.

 

This does two things, it shortens the lever arm the eyepiece is working against and it means I can add heavier eyepiece's before it becomes unbalanced rearward.

 

 

I fabricate brackets and have been known to swap the two speed to the other side.  I use eyepieces like the 31 mm Nagler.

 

Jon

 

Jon


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#32 Rock22

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Posted 04 November 2019 - 08:27 PM

On my ST80 and 80mm apo, I use large rubber bands as suggested by a CN member on a different post from a while back.  I attach one end to the tripod or mount, and the other end to the front of the scope.  I move it closer to the front if I need more tension.  I've used bungee cords before.


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#33 Sarkikos

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Posted 04 November 2019 - 09:13 PM

How much weight do you need if 1.75 pounds is too much?

 

Jack

The Meade weight in post #25 is a full 2 pounds.  The ADM weight farther down is 1.75 lbs but is "machined to screw onto the threaded rods of ADM counterweight kits."   The "bore size" is 0.5". 

 

Mike


Edited by Sarkikos, 04 November 2019 - 09:17 PM.

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#34 Sarkikos

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Posted 04 November 2019 - 09:20 PM

On my ST80 and 80mm apo, I use large rubber bands as suggested by a CN member on a different post from a while back.  I attach one end to the tripod or mount, and the other end to the front of the scope.  I move it closer to the front if I need more tension.  I've used bungee cords before.

No rubber bands or bungee cords for me.  Too Rube Goldberg for my taste. https://www.bing.com...ABE05E6820A0D64

 

I'd be concerned that the bands or cords would loosen or snap.  Too much futzing.

 

Mike


Edited by Sarkikos, 04 November 2019 - 09:27 PM.


#35 gnowellsct

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Posted 04 November 2019 - 09:21 PM

I just balance the scope with my heaviest ocular, nudge it forward a bit, then let the clutch handle both forward and backward imbalance, which is not severe.

 

Greg N

 

p.s. thinking about this some more 3 of my 4 remaining refractors use FT focusers.  So when doing the initial balance the oculars are a smaller % of total rear weight than in most other scopes.  If you had a "light weight" config such as the Vixen R&P focusers the ocular is a higher % of total weight and so imbalance might be more pronounced.    

 

Think of it this way.  If you have more weight to one side you move the scope "forward" and the focuser gets closer to the axis of rotation.  The closer you are to the axis of rotation the less leverage the weight of the eyepiece exerts on the whole set up.  So a heavier focuser is sort of forcing you into a balance point where the weight of the ocular doesn't matter as much.  

 

I also like the idea of an ankle weight.  I bet this suggestion came from a current or former dob owner!  They hang all kinds of things on their scopes for balance.   GN


Edited by gnowellsct, 04 November 2019 - 09:27 PM.


#36 Sarkikos

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Posted 04 November 2019 - 09:23 PM

You have ignored the best solution.,ankle weights.,they worked perfect on my Omni 102 f/6.5.,and you can choose your favorite color.,cheers.,

 

Nope. No ankle weights.  No rubber bands.  No bungee cords.

 

Mike


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#37 Sarkikos

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Posted 04 November 2019 - 09:25 PM

I use Alt-Az mounts with slow motion controls. I push the forward so it's nose heavy but not quite nose heavy enough to over come the friction. I use some friction, just like a Dob, some friction is desirable.

 

This does two things, it shortens the lever arm the eyepiece is working against and it means I can add heavier eyepiece's before it becomes unbalanced rearward.

 

 

I fabricate brackets and have been known to swap the two speed to the other side.  I use eyepieces like the 31 mm Nagler.

 

Jon

 

Jon

 

I really didn't want to buy yet another head.  I want to see if I can get what I have now to work better.

 

Mike



#38 Sarkikos

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Posted 04 November 2019 - 09:26 PM

I just balance the scope with my heaviest ocular, nudge it forward a bit, then let the clutch handle both forward and backward imbalance, which is not severe.

 

Greg N

 

I can't balance the scope with the heaviest ocular. That is the problem.

 

Mike



#39 Sarkikos

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Posted 04 November 2019 - 09:29 PM

Mike,

 

I put a longer dovetail (8” generic vixen from Astronomics) on my AT72ED2 to get it to balance with a 35mm Panoptic, and I must rotate the focuser a few degrees, so the focuser knobs clear the longer dovetail. It works perfectly, but looks a little odd to me because the knobs are no longer parallel with the horizon. I have set up mine, so the right knob with the fine focus mechanism is a touch higher than the left. 

 

gary

 

What mount do you have the 8" dovetail on?  I'm working with a MicroStar.

 

Mike



#40 Sarkikos

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Posted 04 November 2019 - 09:32 PM

Consider a geared head like Manfrotto 410. You'll never worry again about balancing issues.

 

med_gallery_264243_7874_1926161.jpg

 

Looks good.  But how heavy is the head?  How large a tripod would it require?  I want this to remain quick and easy grab-n-go, one hand carrying everything out the door in one trip, down the porch stairs, and around the back of my building.

 

Actually I have an old version of this type of head, a Bogen 3047, that I bought used a couple months ago.  I haven't tried it yet.  Maybe I should give it a try?

 

Mike


Edited by Sarkikos, 04 November 2019 - 09:36 PM.

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#41 gnowellsct

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Posted 04 November 2019 - 09:54 PM

I can't balance the scope with the heaviest ocular. That is the problem.

 

Mike

So you put the heaviest ocular in and it is exerting too much weight, causing the scope to be heavy on the ocular side.  Well, it would help to see a picture.   What is at one level unbelievable about this is that I use a C14 with an apo on top (picture the mirror, the heavy casting, AND the eyepieces, and the FT focuser and eyepiece on the top mounted refractor), that is a lot of weight, it's all concentrated in the back, and the whole thing has to be perched with only a couple of inches from the saddle plate's end and the dec axis of rotation.

 

What is required in that situation is forward offset of the dovetail saddle/clamp.  I don't think even a terminagler would be too much for a properly offset saddle.

 

Here's a picture of what works for C14+Apo+XW30+XW40.  Note that it is indeed the case that if the dovetail saddle were mounted in the classic T formation, hanging equidistant from each side, this would not be a good combo.  But once you offset the saddle, it's pretty easy.  It wasn't my idea.  It was our old buddy Casady who unfortunately left the clamp machining business.   Astro-physics later modified the hole pattern on its saddle clamps to permit offset mounting.  

 

Here's a pic

 

ap900 with saddle offset--CN size.JPG


Edited by gnowellsct, 04 November 2019 - 09:55 PM.


#42 gnowellsct

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Posted 04 November 2019 - 09:57 PM

p.s. yes I understand a C14 ain't no refractor but the balancing issues are very nearly identical.



#43 IMB

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Posted 04 November 2019 - 11:11 PM

Looks good.  But how heavy is the head?  How large a tripod would it require?  I want this to remain quick and easy grab-n-go, one hand carrying everything out the door in one trip, down the porch stairs, and around the back of my building.

 

Actually I have an old version of this type of head, a Bogen 3047, that I bought used a couple months ago.  I haven't tried it yet.  Maybe I should give it a try?

 

Mike

The Manfrotto 410 head weighs 2.7 lb. It can be used with practically any tripod. The tripod in the picture is the previous model of the Oberwerk wooden tripod. When traveling, I attach the head to a Manfrotto 055 tripod. The whole setup as shown in the picture, including an ES82 30 mm eyepiece, weighs 22 lb. This is my quick and easy grab-n-go setup that goes outside in one trip.

 

If you own a Bogen head, I encourage you to give it a try.


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#44 Sarkikos

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Posted 05 November 2019 - 07:31 AM

So you put the heaviest ocular in and it is exerting too much weight, causing the scope to be heavy on the ocular side.  Well, it would help to see a picture.   What is at one level unbelievable about this is that I use a C14 with an apo on top (picture the mirror, the heavy casting, AND the eyepieces, and the FT focuser and eyepiece on the top mounted refractor), that is a lot of weight, it's all concentrated in the back, and the whole thing has to be perched with only a couple of inches from the saddle plate's end and the dec axis of rotation.

 

What is required in that situation is forward offset of the dovetail saddle/clamp.  I don't think even a terminagler would be too much for a properly offset saddle.

 

Here's a picture of what works for C14+Apo+XW30+XW40.  Note that it is indeed the case that if the dovetail saddle were mounted in the classic T formation, hanging equidistant from each side, this would not be a good combo.  But once you offset the saddle, it's pretty easy.  It wasn't my idea.  It was our old buddy Casady who unfortunately left the clamp machining business.   Astro-physics later modified the hole pattern on its saddle clamps to permit offset mounting.  

 

Here's a pic

 

attachicon.gif ap900 with saddle offset--CN size.JPG

You don't have my head and tripod.  I'm not using a big GEM.  (I got rid of all my GEMs.)  I am using a MicroStar Deluxe http://www.universal...arOverview.html on a Vanguard Auctus Plus 324AT.  https://www.bhphotov...us_324AT_Tripod  I want to keep this setup a light-and-easy, one-trip-out-the-door grab-n-go

 

The MicroStar Deluxe has a much shorter saddle than the GEM in your pic.  There is no way to offset the saddle.  It is what it is.

 

If I position the OTA any farther forward on the dovetail, the focuser knobs will hit the dovetail.  I might be able to rotate the OTA sideways in the rings so the focuser knobs avoid the dovetail.  But I don't want to do that if there is another way to balance the setup.  I like to have the focuser knobs under the dovetail, not beside it or above it.

 

Mike


Edited by Sarkikos, 05 November 2019 - 09:15 AM.


#45 ngc6352

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Posted 05 November 2019 - 09:14 AM

I too use cheap velcro wrist/ankle weights to balance my SV80A (focuser heavy).  They’re cheap

and don’t damage the OTA finish.  If memory serves, I paid $10 for two one lb weights at a local

store.  One balances out my 35 Pan.



#46 Sarkikos

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Posted 05 November 2019 - 09:35 AM

OK, so, ankle weights?  The ones I had many years ago were big and bulky.  I'd never wrap anything like that around a telescope OTA. 

 

But these look like possibles: XsScuba Ankle Weights  https://www.xsscuba....s/ankle-weights  

 

Mike



#47 Sarkikos

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Posted 05 November 2019 - 09:38 AM

I too use cheap velcro wrist/ankle weights to balance my SV80A (focuser heavy).  They’re cheap

and don’t damage the OTA finish.  If memory serves, I paid $10 for two one lb weights at a local

store.  One balances out my 35 Pan.

Can you post a link to something similar to what you bought locally?

 

Mike



#48 Sarkikos

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Posted 05 November 2019 - 09:42 AM

Another possibility is some kind of adjustable belt with an attached pouch I could fill with lead shot.  I might have something like this in the house.  I have plenty of lead shot.

 

But I want to minimize the size and bulk of anything I attach to the telescope.  A weight or two that I can screw onto the end of the dovetail would be a cleaner, tighter solution in my opinion. 

 

Mike


Edited by Sarkikos, 05 November 2019 - 09:45 AM.


#49 Spikey131

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Posted 05 November 2019 - 10:21 AM

Televue Balance Aid shifts the center of gravity forward and raises the scope up to allow the focuser to slide forward.

 

Here is a TV 76 with my heaviest EP, the ES 100 20mm, all perfectly balanced:

 

 

 

 

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#50 Spikey131

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Posted 05 November 2019 - 10:46 AM

And here with binoviewers:

 

 

 

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