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AZ/ALT adjustments for DIY EQ Wedge

DIY Equipment SCT Tripod
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#1 rx0

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Posted 01 September 2021 - 08:29 AM

Thinking of building a EQ wedge for a meade lx 200 10" 

 

There are guides for diy wooden wedge that I can follow up to the the azimuth adjustment.

 

I will be using the wedge in only one location +/- 45 miles. This wedge has no adjustments. http://www.covington...ro/woodenwedge/

 

How necessary are fine azimuth/altitude adjustments for imaging? Any ideas for obtaining the metal "P" looking piece (below) for az adjustment? 

 

http://www.astroromp..._wedge_pics.htm

https://www.cloudyni...e/97074-wedge2/

 

 



#2 dcaponeii

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Posted 01 September 2021 - 10:07 AM

Thinking of building a EQ wedge for a meade lx 200 10" 

 

There are guides for diy wooden wedge that I can follow up to the the azimuth adjustment.

 

I will be using the wedge in only one location +/- 45 miles. This wedge has no adjustments. http://www.covington...ro/woodenwedge/

 

How necessary are fine azimuth/altitude adjustments for imaging? Any ideas for obtaining the metal "P" looking piece (below) for az adjustment? 

 

http://www.astroromp..._wedge_pics.htm

https://www.cloudyni...e/97074-wedge2/

When you place your scope of the wedge you will set the software to "polar" mount instead of "alt/az" mount.  Alignment on the pole now becomes about as significant as having your base level in the alt/az mode.  The more accurate that your wedge matches your latitude in angle and faces true north the better.  For planetary imaging close is good enough for DSO you'll need to be fairly accurate otherwise you'll see drift in DEC as your exposures progress.  For visual IMHO, close will always be good enough although any GOTO moves might be off for long slews.


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#3 michael8554

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Posted 01 September 2021 - 10:15 AM

"How necessary are fine azimuth/altitude adjustments for imaging?"

 

For imaging, very.

 

I'd say those wood wedge designs are totally inadequate for a 10".

 

Even the Meade Ultra Wedge bends microns, which is why Milburn, AE etc made custom wedges out of really thick welded steel or aluminium.

 

Wedge02.jpg


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#4 carolinaskies

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Posted 01 September 2021 - 12:24 PM

A wooden wedge made from good hardwood will last many years if properly treated for exposure.  Depending on how you plan to use the wedge, if it's a permanent pier type situation then you can do without the fine adjusters. 

They are great, don't get me wrong, but if you are using it and not removing it between uses then all you need is the means to make the adjustments somewhere besides minute adjuster on the wedge itself.  In permanent installations this typically means shims for altitude and slotted bases for azimuth. 

In such installations a proxy is setup on the pier wedge that mimics the telescope in centerdness to the height and width of the telescope mount.  A polar scope mounted on a bracket can be used.  This allows for setting up the wedge and then you can place the telescope on the wedge and do any fine tuning from there.  With a pier a set of wedge shims are placed to raise or lower the south or north side of the pier. Slotted basses allow the pier to be rotated with a long bar for precise azimuth.  Once it's setup final checks are done and that's it.   

On the other hand if you plan to tear down the telescope regularly it's much better to have the fine adjustments available.  


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#5 dcaponeii

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Posted 02 September 2021 - 07:09 AM

"How necessary are fine azimuth/altitude adjustments for imaging?"

 

For imaging, very.

 

I'd say those wood wedge designs are totally inadequate for a 10".

 

Even the Meade Ultra Wedge bends microns, which is why Milburn, AE etc made custom wedges out of really thick welded steel or aluminium.

 

attachicon.gifWedge02.jpg

The results of planetary imagers using DOB's total negates your comment above.  Even capturing while letting the planet drift across the chip yields outstanding results by many such imagers.  Alignment for planetary imaging is simply not critical.  The capture times are short enough that even a close alignment can keep the image on chip for the three minutes or so needed to complete the video capture.



#6 michael8554

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Posted 02 September 2021 - 09:31 AM

"The results of planetary imagers using DOB's total negates your comment above."

 

I guess I just assumed the OP was talking about DSO imaging, why would he bother with a wedge for short bursts of video for Planetary ??


Edited by michael8554, 02 September 2021 - 09:49 AM.

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#7 dcaponeii

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Posted 03 September 2021 - 10:37 AM

"The results of planetary imagers using DOB's total negates your comment above."

 

I guess I just assumed the OP was talking about DSO imaging, why would he bother with a wedge for short bursts of video for Planetary ??

You could very well be correct.  I guess my brain is still in planetary mode still.




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