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Wedge vs Rotator

astrophotography cassegrain equipment Meade SCT accessories
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#1 aposteriori

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Posted 27 November 2020 - 02:53 PM

I am looking at getting into astrophotography with my 10" LX200. I understand the limitations of a fork mount but right now I am not looking to change my set up. With that in mind I am considering either a Meade X-Wedge or any field rotator (some manufacturers call them de-rotators). Could someone please guide me as to the pros and cons of each option? 

 

Thank you,

 

Clear skies



#2 bobzeq25

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Posted 27 November 2020 - 03:04 PM

I am looking at getting into astrophotography with my 10" LX200. I understand the limitations of a fork mount but right now I am not looking to change my set up. With that in mind I am considering either a Meade X-Wedge or any field rotator (some manufacturers call them de-rotators). Could someone please guide me as to the pros and cons of each option? 

 

Thank you,

 

Clear skies

This has to be said, because I have the knowledge.

 

You'll save some initial money by not changing your setup.  It will cost you more than it's worth in BOTH money and time down the road.  Here's relevant history from someone who tried it. 

 

"I started out with a CPC 800  on a heavy duty wedge.  In hindsight, I'd have started with an 80mm refractor.  I would have saved a lot of money and gotten up the learning curve a lot quicker."

 

Little money right now?  Here's your best path to DSO imaging.  Start with a camera and a lens.  This is not a close call.

 

https://www.astropix...bgda/index.html

 

Alternatively, try Electronically Assisted Astronomy.  There's a forum here.  They can answer that question better.


Edited by bobzeq25, 27 November 2020 - 03:07 PM.

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#3 jrcrilly

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Posted 27 November 2020 - 03:41 PM

Regarding the wedge v. derotator question: Derotators CAN work; nearly all professional observatories use 'em. The issue is - can you get the same degree of precision from an affordable amateur model with moving parts that you can get with a fixed, mechanical device? Generally, no. It is hard enough controlling tracking with one motor. The wedge is a much safer bet.

 

Regarding the previous poster's suggestions: He makes a good point about the difficulty in learning deep sky imaging while working at 2500mm focal length (or even with .63X reducer). Still ,a wedge isn't necessarily a bad idea. A small imaging refractor can easily be piggybacked onto the main OTA (just do a good job of counterbalancing).  It will give a more stable and precise platform for that refractor than any affordable EQ mount would. And, after some experience, you decide to expolre longer focal olengths, you are already there and ready to go.



#4 bobzeq25

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Posted 27 November 2020 - 03:48 PM

Regarding the wedge v. derotator question: Derotators CAN work; nearly all professional observatories use 'em. The issue is - can you get the same degree of precision from an affordable amateur model with moving parts that you can get with a fixed, mechanical device? Generally, no. It is hard enough controlling tracking with one motor. The wedge is a much safer bet.

 

Regarding the previous poster's suggestions: He makes a good point about the difficulty in learning deep sky imaging while working at 2500mm focal length (or even with .63X reducer). Still ,a wedge isn't necessarily a bad idea. A small imaging refractor can easily be piggybacked onto the main OTA (just do a good job of counterbalancing).  It will give a more stable and precise platform for that refractor than any affordable EQ mount would. And, after some experience, you decide to expolre longer focal olengths, you are already there and ready to go.

Depends on how you define "affordable".  An HEQ5-PRO or iOptron 30 PRO would do a dramatically better job of mounting the 80.  $1200.  Note that I didn't recommend spending that.

 

The SCT mount cost Meade maybe $300 to make, or less.  It's not some magic bargain.  The mechanicals were not designed to take the loads involved with tipping the mount 45 degrees.  Particularly the RA bearing.


Edited by bobzeq25, 27 November 2020 - 03:49 PM.


#5 aposteriori

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Posted 27 November 2020 - 04:07 PM

This has to be said, because I have the knowledge.

 

You'll save some initial money by not changing your setup.  It will cost you more than it's worth in BOTH money and time down the road.  Here's relevant history from someone who tried it. 

 

"I started out with a CPC 800  on a heavy duty wedge.  In hindsight, I'd have started with an 80mm refractor.  I would have saved a lot of money and gotten up the learning curve a lot quicker."

 

Little money right now?  Here's your best path to DSO imaging.  Start with a camera and a lens.  This is not a close call.

 

https://www.astropix...bgda/index.html

 

Alternatively, try Electronically Assisted Astronomy.  There's a forum here.  They can answer that question better.

 

 

Thank you for the advice. Unfortunately I already have mostly everything. The only decisions left to be made is that one between a rotator and a wedge.



#6 aposteriori

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Posted 27 November 2020 - 04:09 PM

Regarding the wedge v. derotator question: Derotators CAN work; nearly all professional observatories use 'em. The issue is - can you get the same degree of precision from an affordable amateur model with moving parts that you can get with a fixed, mechanical device? Generally, no. It is hard enough controlling tracking with one motor. The wedge is a much safer bet.

 

Regarding the previous poster's suggestions: He makes a good point about the difficulty in learning deep sky imaging while working at 2500mm focal length (or even with .63X reducer). Still ,a wedge isn't necessarily a bad idea. A small imaging refractor can easily be piggybacked onto the main OTA (just do a good job of counterbalancing).  It will give a more stable and precise platform for that refractor than any affordable EQ mount would. And, after some experience, you decide to expolre longer focal olengths, you are already there and ready to go.

Thank you for the comment and advice.  I have a Meade tube counterweight system. 



#7 Panotaker

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Posted 01 December 2020 - 02:29 PM

I would get a wedge. Mainly because when you finally decide to get an 80mm refractor and gem mount, you can sell the Wedge, you can’t even give away a derotator.


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#8 WadeH237

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Posted 01 December 2020 - 04:10 PM

Thank you for the comment and advice.  I have a Meade tube counterweight system. 

Between the two, I would 100% go with the wedge.  I think that a de-rotator would add significant complexity with no decent return on the effort.  The wedge is far simpler and more reliable.  The question you that should be on your mind is "Where are all the images from amateurs using de-rotators?"  The lack of them should be a sign for you.

 

That said, a wedge solid enough, accurate enough, and easy enough to adjust to work well with your fairly large SCT is going to be expensive.  The one that you are looking at is $600, but I'm not personally familiar with it, so I don't know whether it will be a good experience for you.  From personal experience, I can tell you that if you are going to do any serious imaging, you will likely end up switching to a German Equatorial Mount and a smaller telescope.  At that point, the wedge will be collecting dust on your shelf.

 

If you are building a system primarily for imaging, then I personally wouldn't throw any more investment into what you have.  It's a great setup for visual use, but it's definitely not optimized for imaging (which is the reason that you are getting some of the advice above).


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