Topics

Iexios-100 and getting it to point to the target


MikoSkye
 
Edited

Hi everyone. 

Well, this has been a journey. The results from this mount mean it is worth persevering but OMG, it is sometimes ever so frustrating. I finally can get good polar alignment and unguided tracking works a treat. But I am struggling to get guided tracking. The issue is after I have polar alignment, I cannot get the mount to slew to target using the NSEW controls. The only way I have been able to get the target is to manual release the clutches and swing the whole mount towards the target (polar alignment thereafter somewhat haphazard).

Really could do with some help, as I am sure I am missing something really basic. This is my process:
  • POTH Hub connected and able to control the mount using the sw controls and make sure the GPS coordinates are entered correctly
  • Polar align using SharpCap - minor adjustments using the knobs.
  • Use the POTH Hub sw controls to point to a star away  from Polaris (this is where it fails!!) - it will slew but I cannot get it to point south. All the directional controls work. but it seems as if the E makes it move slowly to the N and thee N  slews a large distance...and so on. 
So I have to manual swing the mount. If I could use the sw to align to a star away from Polaris, I would then:
  • Run PHD2 and calibrate
  • Point at target using POTH Hub sw controls
  • Run guided tracking through PHD2
  • Take many images and sip a warm coffee.
What am I doing wrong!?!
------------
Hardware:
IExios 100 PMC 8 mount / ZWO ASI 120mini guiding camera / Orion 30mm guide scope / Canon 5D4 + EF lenses / Bresser 100w battery pack / Windows 10 laptop  

Software: PHD2, Sharpcap Pro, ASCOM, Cart Du Ciel.


Lloyd Simons
 

Miko,

I wouldn't use the POTH buttons to move the mount. The way they work is not intuitive, Connect your mount (via POTH) to Cartes du Ciel and choose a target to sync the mount. The hand controller buttons in CdC work as expected to make fine adjustments. A properly aligned finderscope or red dot finder can also help if the alignment star is not in your FOV.
  
--
Lloyd Simons
Mattawan, MI
Telescopes: Astrotech AT72ED II, Orion 8" Dobsonian, Tectron 15" Dobsonian, Celestron Super Polaris C8
Imaging Camera: Canon T3i
Guide Camera: QHY5L-IIM on a 60mm F4 Guidescope
Mounts: iExos-100 PMC-8, Vixen Super Polaris
Mount Control: KODLIX gn41 mini PC, Explorestars on a Lenovo Tab 2 A10-70F Android 6.0
Software: N.I.N.A. for imaging, PHD2 for guiding, Sharpcap for PA, Cartes du Ciel, PixInsight


James Ball
 

I had similar problems with the POTH buttons, but I use CdC as also stated by Lloyd it works well.  I also link SharpCap to the mount and use the buttons in it to move the scope for fine tuning and for manual guiding when I am doing planetary photography.  I tried plate solving in SharpCap but have not had luck with that yet though.
--
James Ball
Dawson Springs, Ky
Mounts: iEXOS-100
Scopes: Meade ETX90RA(deforked now) Sky Watcher 150MCT
Camera: ZWO ASI 120MC-S
Software: Explore Stars Android, ASCOM, Stellarium Scope, Stellarium, AS!3, SharpCap, RegiStax6.


MikoSkye
 

Thank you both, I will try CdC instead. Now just need a clear night at the weekend :D
--
Hardware: IExios 100 PMC 8 mount / ZWO ASI 120mini guiding camera / Orion 30mm guide scope / Canon 5D4 + EF lenses / Bresser 100w battery pack / Windows 10 laptop  

Software: PHD2, Sharpcap Pro, ASCOM, Cart Du Ciel.


Jerry Hubbell - Explore Scientific VP Engineering
 
Edited

On Wed, Aug 26, 2020 at 06:22 AM, Lloyd Simons wrote:
I wouldn't use the POTH buttons to move the mount. The way they work is not intuitive,
Not to derail this thread into another topic, my intent is to clarify Lloyd's statement for those not familiar with how the POTH buttons move the mount.

I made this drawing to help people understand what is going on.

Star 1 and Star 2 are the same angular distance apart in the sky when you look at them (blue line). The problem is that in a polar coordinate system which the Celestial Coordinate system is, to move the mount between the two stars is very different in RA and DEC near the North Celestial Pole (NCP) - DEC >70-deg compared to near DEC 0-deg. As shown in the drawing the RA axis only has to move perhaps a few degrees (1 hour in RA = 15-deg), nearly the same as in DEC (15-deg) when at DEC = 0-deg. In contrast, when near the NCP, the RA axis has to move several hours in RA to get the equivalent angular position change as when near 0-deg DEC.

If you are very close to the NCP, perhaps within 10-deg, you may not be able to move the RA axis enough at all to get to the star. The worst case is of course when you are at the NCP you can rotate the mount all you want in RA and the angular position will not change at all, all you see is rotation. The key point when using the POTH is to understand that the POTH is designed for doing small corrections when centering objects. It will move the mount a specific distance in RA and DEC in the Celestial Coordinate System. That is all it can do since the motors drive the mount in this system, not in a cartesian coordinate system

It is important to get your head wrapped around this concept when dealing with polar coordinate systems. Once you understand this, things become much easier when moving the mount. I hope this helps everyone learn this important concept about the POTH and how the mount moves when using the buttons.

 
--
Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home


Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
Mounts
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!


MikoSkye
 

That does make sense. I suppose in my naivety, I was looking at the POTH controls as a way of slewing the mount fairy easily towards the target without me having to release the clutches and then tighten them again. Alas, using the NESW just ended up putting the mount at an odd angle, even if I increased the rate. To my untrained eye it felt like I had no control over where the mount was pointing or where I was slewing, regardless of what directional button I pressed.

So for me (and I am sure others), this is helpful. I will now use the POTH to do fine adjustments and CdC to find a target that is away from Polaris. At least I hope I will!! 
--
Hardware: IExios 100 PMC 8 mount / ZWO ASI 120mini guiding camera / Orion 30mm guide scope / Canon 5D4 + EF lenses / Bresser 100w battery pack / Windows 10 laptop  

Software: PHD2, Sharpcap Pro, ASCOM, Cart Du Ciel.