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Equipment Discussions >> Mounts

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jmiele
Patron Saint?
*****

Reged: 12/04/10

Re: Polar Alignment scope vs. Drift Align? new [Re: psu_13]
      #5377551 - 08/20/12 01:10 PM

Quote:

The thing I found hard about the AP polar scope was that when you turn the reticle to align the stars it seems to loosen up and become more sloppy depending on where you need it to be. I finally gave up and use the scope just to get a rough sighting of Polaris in the scope. It's then usually close enough that the quick drift align goes faster. I put my name on the list for the new Polar scope just because it's such a clever idea.




Yes, the entire assembly feels like it's "slightly" spring loaded and can get hung up not returning to center on occasion. At least that's the best a can do to describe it.

I ended up using PEMPro or TPoint via the computer for any alignment where I required accuracy for imaging. If not, the polar scope has always been sufficient for visual. Even the daytime polar routine outlined in the manual work very well IME. If I thought my A-P polar scope was out of wack, I think I'd send it to A-P and have them look at it. Otherwise I'd just use it.

Joe


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Tom and Beth
Post Laureate


Reged: 01/08/07

Loc: Tucson, AZ
Re: Polar Alignment scope vs. Drift Align? new [Re: Peter in Reno]
      #5377738 - 08/20/12 02:52 PM

Quote:

I cannot align PAS to the mount because rotating Mach1 RA axis does NOT rotate PAS. I would need to get get something like a V-Block and position PAS on the V-Block to see if the reticule is centered but I chose not to do it because I didn't really feel like it and PAS is never intended for accurate polar alignment for imaging. It's a good tool if you go to a dark site and allows you to get pretty close so that Drift Alignment would be faster.

I tried to find a link to A-P PAS for Mach1 about why Mach1 RA axis will NOT rotate PAS but it's not there.

I believe the main reason for this design is to allow "through-the-mount-cabling" otherwise the cables will get all twisted. A-P Mach1 is a fantastic mount and polar alignment is very easy. Just read the manual.

Peter




Please note I wrote "rotate the PAS", not the mount. I'm well aware of the Mach1 axis.


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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: Polar Alignment scope vs. Drift Align? new [Re: Coastal]
      #5378175 - 08/20/12 06:57 PM

Quote:

My project for the week is to adapt a T-thread to the polarscope of my EQ6 (removal of the eyepiece is obviously necessary). Hopefully the PS has enough aperture for my lodestar to pick up several stars. If it can I plan on using astrometry.net to solve the image and overlay the image with a crosshair where NCP is. In theory all I'd need to do is place the NCP at the image centre. I have no idea how well this will work however...




I know of someone whose normal polar alignment routine is similar to this. Instead of a PAS and guide camera, he just uses his regular imaging camera in the main OTA. With the mount aligned near the NCP, he takes an exposure for a few seconds. During the exposure (with the RA clutch released), he rotates the RA axis 180 degrees.

This gives him an image where Polaris transcribes a 180 degree circle in the field. He moves the mount such that the semicircle is centered on the center of the camera's field.

He claims that this works well for him and that he never has a problem with drift or field rotation.


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Coastal
super member


Reged: 04/23/09

Loc: Vancouver island, Canada
Re: Polar Alignment scope vs. Drift Align? new [Re: WadeH237]
      #5378210 - 08/20/12 07:20 PM

Quote:

Quote:

My project for the week is to adapt a T-thread to the polarscope of my EQ6 (removal of the eyepiece is obviously necessary). Hopefully the PS has enough aperture for my lodestar to pick up several stars. If it can I plan on using astrometry.net to solve the image and overlay the image with a crosshair where NCP is. In theory all I'd need to do is place the NCP at the image centre. I have no idea how well this will work however...




I know of someone whose normal polar alignment routine is similar to this. Instead of a PAS and guide camera, he just uses his regular imaging camera in the main OTA. With the mount aligned near the NCP, he takes an exposure for a few seconds. During the exposure (with the RA clutch released), he rotates the RA axis 180 degrees.

This gives him an image where Polaris transcribes a 180 degree circle in the field. He moves the mount such that the semicircle is centered on the center of the camera's field.

He claims that this works well for him and that he never has a problem with drift or field rotation.




That sounds a LOT easier than what I'm doing. The polarscope has the benefit of being pretty easy to collimate and therefore has minimal cone error.

I'd be tempted to try that technique with my guidescope (I can eliminate cone error via the adjustable rings)...I just need a way to start with the dec axis at the correct angle.


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shams42
Pooh-Bah
*****

Reged: 01/05/09

Loc: Kingsport, TN
Re: Polar Alignment scope vs. Drift Align? new [Re: Coastal]
      #5378436 - 08/20/12 09:47 PM

Reading this makes me very happy that I have a Takahashi mount. I can align with enough accuracy for perfect 30 minute subs in 60 seconds or less with the polar scope in my NJP. I've never drift aligned it.

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Greg S
professor emeritus


Reged: 05/20/04

Loc: Encinitas, California
Re: Polar Alignment scope vs. Drift Align? new [Re: shams42]
      #5378551 - 08/20/12 11:10 PM

I had the exact same experience with my new Mach 1 with the PASIL. I agree that it's kind of sloppy and the scope seems subject to moving out of alignment. I did the quick alignment and got it back into alignment but the PAS was WAY off!

Breezing through this thread I see lots of comments from people who say only drift alignment works and that Polar Scopes are for rough alignment. If this PASIL is any example of what they have used then they are absolutely correct!

However, if you have every owned a TAK mount you know that the TAK polar scope is FANTASTIC. You really DON'T need to drift align when guiding which is great.

I really hope the new right angle finder scope from AP is as good as the TAK.


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Dave MModerator
Postmaster
*****

Reged: 08/03/04

Loc: Ohio
Re: Polar Alignment scope vs. Drift Align? new [Re: Greg S]
      #5378959 - 08/21/12 08:46 AM

Quote:

I really hope the new right angle finder scope from AP is as good as the TAK.




I sure hope so also.
Making it a right angle polar alignment scope was a nice idea.


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CounterWeight
Postmaster
*****

Reged: 10/05/08

Loc: Palo alto, CA.
Re: Polar Alignment scope vs. Drift Align? new [Re: Dave M]
      #5379290 - 08/21/12 12:31 PM

It's a great idea as long as diagonal done very well? - though I first read about it here on another mount, I thought ES was going to market that other mount?

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Peter in Reno
Postmaster
*****

Reged: 07/15/08

Loc: Reno, NV
Re: Polar Alignment scope vs. Drift Align? new [Re: CounterWeight]
      #5379375 - 08/21/12 01:11 PM

I Googled for "Takahashi polar alignment scope" and found the operating manual. I read the part about using the polar scope and can't believe how easy is to use it. I wondered why other mounts never use this kind of polar scope unless Takahashi owns the patent for their polar scope? Maybe the patent finally expired by now?

http://www.takahashiamerica.com/manuals/NJP_Manual.pdf

Peter

Edited by Peter in Reno (08/21/12 01:13 PM)


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Polar Alignment scope vs. Drift Align? new [Re: Peter in Reno]
      #5379626 - 08/21/12 03:50 PM

The easier way with a Mach 1 is to do this:

Load it up at park 3.

Have the mount DRIVE ITSELF to Park 1.

Open the clutches and level the OTA and mount arm.

GOTO to a star near the zenith.

Adjust the altitude to center it.

GOTO to a star near the horizon.

Adjust the azimuth to center it.

Use the mount.

The fact the mount is always aligned is why this works. It's freaking awesome.

Like I said, my PAS path is used for cables.

-Rich


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psu_13
sage


Reged: 05/30/10

Re: Polar Alignment scope vs. Drift Align? new [Re: Peter in Reno]
      #5379805 - 08/21/12 05:47 PM

When I was shopping for expensive mounts the elegance of the Tak polar scope was the main thing that kept it in the running vs. the Mach 1. In the end the excellent support and documentation that AP provides won out. Still, one does wonder why no one else makes polar scopes like that.

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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: Polar Alignment scope vs. Drift Align? new [Re: psu_13]
      #5380110 - 08/21/12 10:11 PM

My old Ultima 2000, that I bought in 1998, had a finder scope with a reticule very similar to the Tak's polar scope. It also came with a tool (a bit like a circular slide rule) to determine the position angle of Polaris.

So it's not just a Tak thing. I'm also a bit surprised that nobody else has done it until now.


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Greg S
professor emeritus


Reged: 05/20/04

Loc: Encinitas, California
Re: Polar Alignment scope vs. Drift Align? new [Re: WadeH237]
      #5380311 - 08/22/12 01:01 AM

StarHawk,

I just thought about what you suggested and makes all the sense in the world as you are aligning Altitude at the perfect spot and Azimuth at the perfect spot too. Anywhere in the plane works the same.

This is where AP takes some getting used to. Unlike other mounts it's just programed with the sky in it, IF PROPERLY POLAR ALIGNED. Other mounts have "models" to adjust for misalignment. Two very different systems.

I think I can get used to the AP system but the emphasis needs to be on proper polar alignment.

But, I still want a TAK scope for my Mach 1.


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vdb
sage


Reged: 12/08/09

Re: Polar Alignment scope vs. Drift Align? new [Re: Greg S]
      #5380783 - 08/22/12 10:17 AM

Yeah the Tak polarscope is great but dec guiding is a @#$% ... (got one so I know what I'm talking about)
The same polarscope principle is found in the IEQ45, and 30 minute subs are easy ...
The losmandy polar-scope is junk ... 15 minutes max, drift is necessary for longer subs
(I aligned all of my polar-scopes)
Drift really takes not that long with PHD, I have one setup without PS and it took me 10 minutes to get 2.4 meter focal length to do 30 minute subs ... you need to be level though ...

Edited by vdb (08/22/12 10:19 AM)


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Footbag
Post Laureate
*****

Reged: 04/13/09

Loc: Scranton, PA
Re: Polar Alignment scope vs. Drift Align? new [Re: vdb]
      #5380926 - 08/22/12 11:32 AM

I've also had enough luck where PHD drift aligning only takes 10 or so minutes. Of course if a polar scope could remove that from my setup, I'd buy it in a second.



Edited by Footbag (08/22/12 01:08 PM)


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Polar Alignment scope vs. Drift Align? new [Re: Greg S]
      #5381302 - 08/22/12 03:40 PM

Greg,

Thank you- I now feel like I did some good on this thread!

Unless Roland is going to fulfill the lists, he has to accept the fact the bulk of his mounts will carry non-AP scopes.

-Rich


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