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Lightbridge Related Question

Reflector
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#1 Linked-In-The-Stars

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Posted 17 April 2021 - 06:13 AM

Good morning y'all..

 

So a good question as I am not quite understanding why this would be myself, but..here goes. So I purchased a nice digital angle finder to help "guide" me in getting closer for objects in the sky. And this may tie into some other ?'s...

But, when I put the angle finder on the primary "bucket", I will get a reading of whatever the angle may is positioned at, now, If I put the angle finder on the secondary assembly, (upper) I get another angle but completely different number AND dependent also WHERE I put it on the secondary assembly. (Whether it's close to the finder, focuser, etc. the angle changes a few degrees usually less than 3) But more importantly, The difference is somewhere between 6-10 degrees from the top (secondary) and bottom(primary) placement, only if I place the angle finder directly on the "spine/back" of each assembly. I hope this makes "sense"....Is there a good reason for this, should I be using the primary for where I set the finder, or where should the placement be set to be most accurate?? Or is this a fairly normal thing? is this a flaw in the assembly of the scope build in itself being a truss design?? Just want to know so I have a better understanding why this is...confused1.gif 

To add to this, if anyone knows anything about upgraded tube assembly's, or even a better more solid base build kit could you add that info or just pm me? Just want to see what's out there. Thanks in advance and hopefully I explained this well enough to get my message across.

 

Clear skies..

 

Dustin
 



#2 ScottW

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Posted 17 April 2021 - 08:39 AM

Dustin,

 

Check that the struts are tight at both ends.  That sounds like alot of play.

 

I had a 12" LB and used a digital level and others have too.

 

Scott



#3 Linked-In-The-Stars

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Posted 21 April 2021 - 04:34 AM

Thanks Scott, I did check the trusses and all was good on both ends. So no issues there. Maybe this is somewhat normal or hasn't really been noticed. I have noticed people have placed these digital angle finders in different spots on the scope though.

 

Dustin



#4 Jon Isaacs

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Posted 21 April 2021 - 04:42 AM

Dustin:

 

What model angle gauge are you using?

 

Do any of the readings agree with Sky Safari or a similar app?

 

Jon



#5 Linked-In-The-Stars

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Posted 21 April 2021 - 04:48 AM

Hi Jon,

It is a Johnson digital angle finder I picked up from Lowe’s. And I have yet to be able to test it out on a known object being skies here have been pretty gloomy as of late. The first day I picked it up (and this is where I was wrong) I tried going out and locating some dso right away. Instead of checking where I placed it and double checking it against a known object and it’s coordinates. I suppose this is where I should have started and that would’ve told me the best placement on my scope? Thanks

#6 ScottW

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Posted 21 April 2021 - 06:44 AM

Jon,

 

Take a look at my post, "A Simple Alt digital level".  It allows one to fine adjust the Alt reading.

 

Scott


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#7 RobertMaples

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Posted 21 April 2021 - 01:35 PM

Good morning y'all..

 

So a good question as I am not quite understanding why this would be myself, but..here goes. So I purchased a nice digital angle finder to help "guide" me in getting closer for objects in the sky. And this may tie into some other ?'s...

But, when I put the angle finder on the primary "bucket", I will get a reading of whatever the angle may is positioned at, now, If I put the angle finder on the secondary assembly, (upper) I get another angle but completely different number AND dependent also WHERE I put it on the secondary assembly. (Whether it's close to the finder, focuser, etc. the angle changes a few degrees usually less than 3) But more importantly, The difference is somewhere between 6-10 degrees from the top (secondary) and bottom(primary) placement, only if I place the angle finder directly on the "spine/back" of each assembly. I hope this makes "sense"....Is there a good reason for this, should I be using the primary for where I set the finder, or where should the placement be set to be most accurate?? Or is this a fairly normal thing? is this a flaw in the assembly of the scope build in itself being a truss design?? Just want to know so I have a better understanding why this is...confused1.gif 

To add to this, if anyone knows anything about upgraded tube assembly's, or even a better more solid base build kit could you add that info or just pm me? Just want to see what's out there. Thanks in advance and hopefully I explained this well enough to get my message across.

 

Clear skies..

 

Dustin
 

My digital angle finder reads the same on either assembly.  I find your description a little confusing - you say you're placing it along the "spine/back" of each assembly, which is the correct way to use it (if you mean the imaginary line running along the top of the scope when it is pointed at the horizon), but you also mention different readings depending on where you put it ("close to the finder, focuser, etc.").  On my 10" Lightbridge the finder is along the spine and the focuser is angled away from it, so I can't place the digital angle finder closer to the focuser.  In fact, on the upper cage there is only a very small area where I can place it and that is between the finder and the front opening of the scope.  I can't even place it on the other side of the finder (toward the trusses) because it interferes with one of the truss knobs.

 

The only thing I can think of is make sure you are actually placing it along the "spine" and make sure that it is running parallel to the spine because if it is turned slightly you'll get erroneous readings.



#8 Old Rookie

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Posted 21 April 2021 - 07:27 PM

It shouldn't make a difference where it's placed.  Some people like it on the lower assembly, others on the secondary assembly.  There is a way though that you can zero out the digital gage no matter where you locate it and get consistent readings.

1.  Set it on the spine of either the lower/upper assembly.

2.  Point the dob at a star.  For this example Polaris.  

3.  Zero out the digital gage.

4.  Lower the tube until the digital gage reads whatever the altitude is per your software.  In my case Polaris is 40°.  So with the dob pointed at Polaris and the angle gage reading zero, I would lower the dob to -40°.

5.  Re-zero the angle gage.  At this point the angle gage should be zero'ed out and ready for the night.  Check by pointing back to Polaris for example.



#9 Tom Stock

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Posted 24 April 2021 - 10:21 AM

Hi Jon,

It is a Johnson digital angle finder I picked up from Lowe’s. And I have yet to be able to test it out on a known object being skies here have been pretty gloomy as of late. The first day I picked it up (and this is where I was wrong) I tried going out and locating some dso right away. Instead of checking where I placed it and double checking it against a known object and it’s coordinates. I suppose this is where I should have started and that would’ve told me the best placement on my scope? Thanks

Set it to horizontal and level.  Check it with a bubble level to determine which location is best for mounting where the bubble level matches the angle finder.


Edited by Tom Stock, 24 April 2021 - 10:22 AM.


#10 Starman1

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Posted 29 April 2021 - 04:36 PM

I sold a lot of these scopes.

 

1) the tube sections are rarely round  Measure the diameter at several places and you'll get different numbers.

 

2) The poles are not the same length so the angle the top makes with the bottom will vary depending how it's set up.

I suggest building the scope with the poles in different places to see when orientation results in the best agreement between bottom and top, then mark them so you always

   reassemble the scope in the same way.

 

3) Then follow the recommendations of the previous posts.

 

Additionally: Super-tighten ever screw that holds a ring to one end of the tube sections or other.  The screws can slip in the holes.  If you have the time, put star washers under the heads of every screw so it bites into the tube.

Knurl the ends of the poles (the flat sections) so they bite into the aluminum blocks and won't slide when the scope points low.




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