Re: Mach2 - Elongated stars


Bill Long
 

I did notice a huge difference in using the clutches to balance versus my Mach 1 I had. On my Mach 1 the DEC axis was always really hard to feel out in terms of balance. The Mach 2 is very much like it's bigger brother the 1100. Easy to balance and the clutch knobs on the Mach 2 are really well placed and easy to work with. 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Roland Christen via groups.io <chris1011@...>
Sent: Thursday, March 11, 2021 7:35 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Mach2 - Elongated stars
 
hello Yanzhe,

I have done some more digging and testing with regard to your guiding results. You had said that your Dec axis is not balanced. Unbalance puts strain on the worm teeth which increases friction and can inhibit smooth motion at the sub-arc sec level. For example, a 1 lb unbalance at 30 inches distance produces 10lb of pressure on the worm teeth. The resulting friction is then 10 times what it would be if the axis was properly balanced. High static friction on the Dec axis causes stick-slip motion as the axis is being nudged along in small steps during a typical guiding run. 

In RA the unbalance is not as critical because the worm is constantly turning, and the dynamic friction is much lower than the static friction of the Dec axis.

We made the Mach2 with clutches that can be loosened to achieve good balance. If you fully loosen the Dec knobs with the mount in Park 4 or 5 position, it should be balanced enough to not move on its own. It should feel light in both directions and stay put when you let go of the scope. Try to get at least this much balance on your rig, and you will see that it will guide exceptionally well and give you the performance that you want.

Rolando



-----Original Message-----
From: yanzhe liu <liuyanzhe@...>
To: main@ap-gto.groups.io
Sent: Thu, Mar 11, 2021 12:36 am
Subject: Re: [ap-gto] Mach2 - Elongated stars

Ray,

I am able to run "AP Log Zipper", there are 2 files shown in the app: ap.ini and Setting.apdb, however both were dated 12/29/2018. Maybe I did not enable ASCOM log.

Yanzhe

On Sun, Mar 7, 2021 at 7:37 PM Ray Gralak <iogroups@...> wrote:
Yanhze,

> Where is ASCOM driver log? I dont use APCC, I use SGPro.

The AP V2 ASCOM driver, which you must use with SGPro, comes with a log zipper utility called "AP Log Zipper". You should be able to find it from the Windows start menu by typing that name. The utility will grab the log files for X number of days in the past. If you can't find it, you probably didn't install it when you installed the AP V2 driver. In that case, just reinstall the AP V2 driver and select the option to install it.

BTW, you can use APCC with SGPro. In fact, it is recommended. An APCC Pro license comes with your Mach2 mount, but you must contact A-P to get it.

-Ray


> -----Original Message-----
> From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of yanzhe liu
> Sent: Sunday, March 7, 2021 4:19 PM
> To: main@ap-gto.groups.io
> Subject: Re: [ap-gto] Mach2 - Elongated stars
>
> Ray,
>
> Where is ASCOM driver log? I dont use APCC, I use SGPro.
>
> Yanzhe
>
> On Sun, Mar 7, 2021 at 10:45 AM Ray Gralak <iogroups@...> wrote:
>
>
>       Hi Yanzhe,
>
>       Can you zip and post your PHD2 logs, as well as APCC/AP V2 ASCOM driver logs?
>
>       There might be something useful there.
>
>       -Ray
>
>       > -----Original Message-----
>       > From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of yanzhe liu
>       > Sent: Sunday, March 7, 2021 10:12 AM
>       > To: main@ap-gto.groups.io
>       > Subject: Re: [ap-gto] Mach2 - Elongated stars
>       >
>       > Roland,
>       >
>       > I will check my mount serial number later as I just packed everything due to rain forecast.
>       >
>       > My camera's orientation was 0/180 degree, so I assume top to bottom elongation would be DEC.
>       >
>       > I dont have any picture of my setup, I just tore it down since it will be rainy this week. My setup is
>       > FSQ106+OAG+16803, image scale is 3.5".
>       > I was imaging Rosetta Nebula, after it was just past meridian for 2-3 hours.
>       >
>       > I used PHD2 drift for PA, it reported <5' PA error, I am waiting for polemaster adapter so I can confirm I get
> good PA
>       > next time.
>       >
>       > DEC was out of balance because my setup was rear end heavy, if it was in balance position then I could
> not rotate
>       > my CCD in all directions. My guess is that the DEC balance was off by less than 1lb. In the next test, I can
> balance
>       > DEC to see if the issue still exists.
>       >
>       > My suspicion is that if DEC balance is off, then DEC might creep under gravity, even PA is perfect. So you
> might
>       > see DEC continually drift  then gets corrected by PHD2 periodically.
>       >
>       > Yanzhe
>       >
>       > On Sun, Mar 7, 2021 at 9:35 AM Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
>       >
>       >
>       >       Couple of questions:
>       >
>       >
>       >       1 - what's the mount's serial number
>       >       2 - which axis is the elongation
>       >       3 - which direction was the scope pointing (RA-Dec)
>       >       4 - what scope and focal length or what is the arc sec per pixel.
>       >       5 - do you have a picture of your setup?
>       >
>       >
>       >
>       >       One comment about balance - it should be easy for you to completely balance the scope with the
> clutches
>       > loose. Can you estimate how many lb out of balance your scope is in Dec? Normally i would not think this
> would
>       > have any effect, but doesn't hurt to check this.
>       >
>       >
>       >
>       >       Roland Christen
>       >       Astro-Physics Inc.
>       >
>       >
>       >
>       >
>       >       -----Original Message-----
>       >       From: yanzhe liu <liuyanzhe@...>
>       >       To: main@ap-gto.groups.io
>       >       Sent: Sun, Mar 7, 2021 12:44 am
>       >       Subject: [ap-gto] Mach2 - Elongated stars
>       >
>       >
>       >       Testing new mach2 for a couple of nights. It works great out of the box and I am very pleased.
>       >
>       >       One issue bothering me is that I got slightly elongated stars across the entire image (15min Ha sub).
>       >       The exact same telescope/CCD were used with another mount and stars were round, I am wondering
> what I
>       > should check (I think there was due to some setup issue, but I could not figure it out).
>       >       - Used OAG for guiding, so there should not be any flexure.
>       >       - CCD orientation was 0/180 degree. The stars were elongated top to bottom.
>       >       -  I did polar alignment with PHD2 drift align. PA error should be < 5'. The field rotation of each sub is
> ~0.01
>       > degree, much larger than the other system (but elongated stars do not look like field rotation, they were
> same
>       > across the image)
>       >       - Both RA and DEC guiding curves looked smooth, had similar RMS. DEC correction was mainly to
> one
>       > direction.
>       >       - DEC balance was slightly off, camera heavy. Is Mach2 DEC sensitive to this? Will the guiding/image
> be
>       > affected?
>       >
>       >       I dont think any of the above is of particular concern, except DEC balance. Any comment/help is
> appreciated.
>       >
>       >       --
>       >       Roland Christen
>       >       Astro-Physics
>       >
>       >
>       >
>       >
>       >
>       >
>
>
>
>
>
>
>
>
>







--
Roland Christen
Astro-Physics

Join main@ap-gto.groups.io to automatically receive all group messages.