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How Do You Balance Your Small Refractor for Heavy Eyepieces?

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#151 Sarkikos

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Posted 17 February 2020 - 11:19 AM

Why not just use a longer dovetail bar. We all have extra dovetail bars. They come on and off in a minute and allows the entire scope to re balance easily.  Ive use this on my AT-92 with the barlow in front of the 2" diagonal with large 2" eyepieces, and their is plenty of room to always be in balance just by sliding the dovetail in the saddle. 

These are little lightweight scopes and require no effort to adjust the position of the scope.

 

 

...Ralph

The longer dovetail gets in the way of the focusing knobs.  I've mentioned this several times in this thread.  The purpose of the risers is to elevate the focusing knobs above the dovetail.

 

Also, I'm not mounting the telescope on a GEM.  I got rid of all my GEMs.  I don't like them.  I have various alt-az heads that go on tripods.  I like having the focusing knobs positioned horizontally and to have them stay in that position.  So no GEM, and no focusing knobs shifted vertically to avoid a long dovetail.

 

Mike



#152 aa6ww

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Posted 17 February 2020 - 01:55 PM

I added the 1" spacers so the dew shield would not bang against the 11" dovetail bar and the focuser is free to rotate with the dovetail below it.
When I'm using 2" eyepieces, I slide the dovetail/Scope combo forward even more then in my photo. The back of the length of the dovetail bar gets completely used up that way. I use the length of the front of the bar for either a Laser pointer, or my STarsense camera.

This set up also works very well when I'm using my StarGuy Alt-Az mount also, but I seldom use that mount since I prefer tracking mounts. The Starguy is great for terrestrial viewing.

...Ralph


I don't understand how the question relates to the development of the OP's request.  Ignoring the fact that we don't all have "extra dovetail bars" (mine are all accounted for on scopes), your image shows what appear to be risers, in addition to a very long dovetail bar (another item I don't have and I suspect that is somewhat uncommon thing for others as well.)   That looks like a reasonable solution for the longer/heavier objective AT92 triplet, but not necessarily the optimum for an AT72 doublet with a lighter objective and shorter lever arm.  
 
Part of what I gathered from the thread is that a 30mm spacer will allow the AT 72EDII's focuser knobs to clear in rotation.  That is a handy bit of information.   A second dovetail won't provide enough space to clear the knobs from what I see.  So purchasing a more expensive extra long dovetail to go with the shorter Vixen doesn't seem to be as full of a solution.  
 
At any rate, spacers and a moderately sized dovetail seem a far more elegant and simple solution to me.   Probably more cost effective too, especially since it is possible to fabricate custom spacers for a fraction of the cost.


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#153 Lt 26

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Posted 17 February 2020 - 05:26 PM

Stuck a TV20mm plossl in the SV70 and called it good.

 

Dereck


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#154 Redbetter

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Posted 17 February 2020 - 11:25 PM

Stuck a TV20mm plossl in the SV70 and called it good.

That is fine if one isn't interested in wide/rich field views and modest exit pupil.  But to me that fails to take advantage of a small scope's primary strength, rich field/large exit pupil viewing.    

 

If I understand correctly the SV70 is an f/6 that will provide 2.33 deg of true field and 3.3mm exit pupil when combined with a 20mm Plossl.  By comparison a 41 Pan will provide  6.28 deg of field with a 6.8mm exit pupil.  

 

If a person wants the same magnification/exit pupil as the 20 Plossl, then a 20 Nagler still has 3.74 deg of field, enough to fit the full Veil.  


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#155 Jon Isaacs

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Posted 18 February 2020 - 08:11 PM

The longer dovetail gets in the way of the focusing knobs.  I've mentioned this several times in this thread.  The purpose of the risers is to elevate the focusing knobs above the dovetail.

 

Also, I'm not mounting the telescope on a GEM.  I got rid of all my GEMs.  I don't like them.  I have various alt-az heads that go on tripods.  I like having the focusing knobs positioned horizontally and to have them stay in that position.  So no GEM, and no focusing knobs shifted vertically to avoid a long dovetail.

 

Mike

 

I like ALT-AZ mounts.

 

One trick is to flip the focuser pinion assembly so the two speed is on the left. Its doable with many focusers but not all focusers.

 

Jon


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#156 allen g

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Posted 18 February 2020 - 10:25 PM

No balancing necessary with the DiscMount 



#157 Sarkikos

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Posted 19 February 2020 - 07:55 AM

I like ALT-AZ mounts.

 

One trick is to flip the focuser pinion assembly so the two speed is on the left. Its doable with many focusers but not all focusers.

 

Jon

Yes, I would prefer to have the two-speed knob on the left, since I like to have the telescope on the left side of the mount.  I like to be at the left of the telescope, so my right eye is closest to the eyepiece.  I wish focusers came with the fine focuser on the left side.  To me, that should make more sense to observers who are dominant right-eyed.

 

I'm right-handed, but I have no problem at all fine focusing with my left hand.  How much skill does that really take?  I know some observers make a big deal about this, and claim they can fine focus only with their dominant hand.   I guess I'm amibidextrous enough that it doesn't matter to me.  The only things I can't do with very well my left hand are write and draw.  shrug.gif

 

But I'd be reluctant to switch the knobs on any focuser.  I'd be concerned that the focuser would not work well after I'm done with it.  grin.gif

 

Mike


Edited by Sarkikos, 19 February 2020 - 07:58 AM.

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#158 Sarkikos

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Posted 19 February 2020 - 08:00 AM

No balancing necessary with the DiscMount 

I have a DM-6.  But it's quite heavy and bulky, and requires a bigger and sturdier tripod.  I don't want to mount small grab-n-go scopes on the DM-6.

 

Mike



#159 Jon Isaacs

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Posted 19 February 2020 - 09:47 AM

But I'd be reluctant to switch the knobs on any focuser.  I'd be concerned that the focuser would not work well after I'm done with it.  :)

 

Mike

 

 

Mike:  

 

It's a valid concern. Some Focusers are easier than others.  I'm confident that it will be at least as good but I've worked on quite a number of Focusers.

 

Jon


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#160 Mike W

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Posted 19 February 2020 - 03:16 PM

Here's a link to what you need:

 

http://televue.com/e...d=23&Tab=_equil

 

CU-2.jpg


Edited by Mike W, 19 February 2020 - 03:20 PM.


#161 Sarkikos

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Posted 20 February 2020 - 09:34 AM

Here's a link to what you need:

 

http://televue.com/e...d=23&Tab=_equil

 

attachicon.gifCU-2.jpg

I already have one.  But an Equalizer won't solve the problem of a heavy eyepiece unbalancing the telescope if I can't shift the telescope forward on the mount to compensate for the imbalance.  I was not able to shift the telescope forward because the focuser knob would butt against the end of the dovetail.  This is solved by installing risers to position the telescope above the dovetail.

 

Mike



#162 gwlee

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Posted 20 February 2020 - 11:58 AM

No balancing necessary with the DiscMount 

My AT72ED2 has exactly the same problem on my DiscMount. 



#163 gwlee

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Posted 20 February 2020 - 12:00 PM

Here's a link to what you need:

 

http://televue.com/e...d=23&Tab=_equil

 

attachicon.gifCU-2.jpg

Nope, it will make it worse. The problem is that there’s already too much weight on the focuser end of the scope. 


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#164 Sarkikos

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Posted 20 February 2020 - 03:14 PM

My AT72ED2 has exactly the same problem on my DiscMount. 

Exactly what problem?  I have put several different scopes on the DM-6:  EdgeHD 8", 6" f/5 achro, SW120 ED.  I can adjust the mount so the scope doesn't move when I switch between light and heavy eyepieces.  Of course, you should adjust for balance as best you can, positioning the scope about midway between accessory weight extremes.

 

Mike


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#165 gwlee

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Posted 21 February 2020 - 12:21 AM

Exactly what problem?  I have put several different scopes on the DM-6:  EdgeHD 8", 6" f/5 achro, SW120 ED.  I can adjust the mount so the scope doesn't move when I switch between light and heavy eyepieces.  Of course, you should adjust for balance as best you can, positioning the scope about midway between accessory weight extremes.

 

Mike

Mike,

 

With 2” accessories my AT72ED2 is stern heavy, which requires a long dovetail to balance the scope, and the focuser must be rotated off level to allow the focuser knobs to clear the long dovetail. If I understand you correctly, you have the same problem with your AT72ED2 mounted on your MicroStar. The problem is the same whether the scope is mounted on my DM4 or my DwarfStar.

 

The altitude resistance of both my mounts can be adjusted to keep an unbalanced scope from moving when an EP is changed, but that’s not the problem. An unbalanced scope doesn’t track as well, and increasing the altitude tension doesn’t balance the scope, it just makes the scope harder to move./point. 

 

I try to perfectly balance the scope on the mount by sliding it for and aft with no altitude tension.Then, add just enough altitude tension to prevent the scope from moving when my heaviest EP is removed. 
 

 

Gary


Edited by gwlee, 21 February 2020 - 01:11 AM.

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#166 Sarkikos

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Posted 21 February 2020 - 12:26 PM

I agree.  It's better to actually balance a scope on any mount rather than increasing the tension on the detention knobs for "virtual" balancing.  But some mounts are better than others at "virtual" balancing.

 

IME, the DM-6 is pretty good at simulating a balanced setup by an adjustment of the knobs - including the tension adjustment knob that's inside the head.  A lot better than the MicroStar or M2.  The DM-6 does a good enough job if I physically balance the scope about midway between balance for lightest and heaviest setups, and then set the internal tension knob as necessary to keep the end of scope from falling. 

 

My 501HDV head has built-in tension springs which simulate actual balance pretty well as long as I don't overload it.  An AT60ED is great on my 501HDV.  I keep a longish plate for the 501HDV on my AT60ED.  I wouldn't even bother putting a small scope like the AT60ED on anything else.

 

Mike


Edited by Sarkikos, 21 February 2020 - 12:32 PM.


#167 seasparky89

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Posted 22 February 2020 - 05:05 PM

I came up with a very easy and economical solution for my AT72edii by using very inexpensive cylindrical risers and 35mm M6 socket head screws on an existing solid Vixen-type dove tail.  The URL for the anodized spacers is: https://www.amazon.c...0?ie=UTF8&psc=1

(and they cost $10.99).  Attached is a picture of the setup.

 

Stan

Attached Thumbnails

  • AT72edii on Spacers.jpg

Edited by seasparky89, 22 February 2020 - 05:07 PM.

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