Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

CPWI Accuracy with ALT-Z Mount

cassegrain Celestron EAA mount SCT
  • Please log in to reply
5 replies to this topic

#1 sandconp

sandconp

    Mariner 2

  • *****
  • topic starter
  • Posts: 243
  • Joined: 21 Feb 2018
  • Loc: Minnesota USA

Posted 21 May 2019 - 12:15 PM

Now that I have resolved my WiFi issues on my laptop, I was ready to try CPWI again with my Evolution ALT-Z mount.  Has anybody had any issues with the accuracy of CPWI?  The first thing CPWI asked me is if I wanted to calibrate my scope which I thought was kind of strange since that is usually done after my Star Sense Auto Alignment centering with a course and then a fine adjustment on a star.  So I performed that step making sure that my mount was facing north and I picked Arcturus and the altitude was way off but the azimuth was in the general vicinity.  So I manually slewed to Arcturus with the help of my Telrad finder and centered the star then I performed a Star Sense Auto Alignment from CPWI.
 
I then proceeded to select a few stars to check for accuracy and CPWI wasn't even close so I gave up and went back to using the Star Sense Hand control first doing a Star Sense Auto Alignment then a calibrate on a bright star and from then on, everything was spot on.
 
I am running the general release version of CPWI and no longer the Beta which has issues early on which is to be expected with Beta code.
 
Is anybody having any success with their ALT-Z and CPWI and if so, would you be willing to share your experiences?
 
My backup is to use the Star Sense Hand Control or Stellarium from my PC wirelessly and perform the alignment from the hand control and then let Stellarium take over but I thought I would give CPWI a chance since everything can be done from the software instead of the hand control.

Edited by sandconp, 21 May 2019 - 04:27 PM.


#2 Michael_Swanson

Michael_Swanson

    Vanguard

  • *****
  • Posts: 2076
  • Joined: 23 Apr 2003

Posted 21 May 2019 - 07:18 PM

This is from a guy who hasn't used CPWI, but I'm certain that after you perform a StarSense alignment in CPWI (be sure to have at least 5 alignment points), you will need to perform the camera calibration.

 

Lots of people at the TeamCelestron beta site have used CPWI on Alt-Az mounts with very good accuracy.

 

Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com



#3 sandconp

sandconp

    Mariner 2

  • *****
  • topic starter
  • Posts: 243
  • Joined: 21 Feb 2018
  • Loc: Minnesota USA

Posted 22 May 2019 - 10:07 AM

Mike,

Dont’t you think it’s odd the CPWI give you an option to calibrate before performing a Star Sense Auto Alignment? Couldn’t I do the calibrate after the SS Auto alignment and then add the alignment points?

Using the SS Hand Control, you perform the calibrate after the SS Auto Alignment if you choose to do so.

Edited by sandconp, 22 May 2019 - 10:08 AM.


#4 Michael_Swanson

Michael_Swanson

    Vanguard

  • *****
  • Posts: 2076
  • Joined: 23 Apr 2003

Posted 22 May 2019 - 08:14 PM

Mike,

Dont’t you think it’s odd the CPWI give you an option to calibrate before performing a Star Sense Auto Alignment? Couldn’t I do the calibrate after the SS Auto alignment and then add the alignment points?

Using the SS Hand Control, you perform the calibrate after the SS Auto Alignment if you choose to do so.

Is the option specifically to calibrate the camera?  It might be a calibration step to familiarize CPWI with your mount.

 

Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com



#5 Noah4x4

Noah4x4

    Vanguard

  • *****
  • Posts: 2424
  • Joined: 07 Apr 2016
  • Loc: Colchester UK

Posted 22 May 2019 - 11:25 PM

Mike is correct.

 

Whether using a Starsense HC, or CPWI/PC or Android/IOS tablet, these are all independent control devices that need to be calibrated independently of each other. You should also adopt only one for Alignment/GoTo (albeit the HC direction buttons still work with the other two). 

 

You also need to add additional alignment points in EACH device for best success.

 

I have used all three with superb accuracy, but I have been incredibly patient and careful with these processes. For example repeatedly calibrating until my calc-star is centred in to a 12mm illuminated reticle EP. This step might give a clue as regards issues when calibrating using camera/screen. Where is its exact centre? You need to use camera zoom to focus on a very small region of interest hence mimicking the use of a 12mm reticle EP.. if you attempt calibration on a wide FOV (notably on Hyperstar) it is little wonder accuracy is pants. Or may be I just got lucky as I got good CPWI accuracy before the calibration step. My Evolution is also now mounted on a wedge, so maybe that helps too. 


Edited by Noah4x4, 22 May 2019 - 11:29 PM.


#6 sandconp

sandconp

    Mariner 2

  • *****
  • topic starter
  • Posts: 243
  • Joined: 21 Feb 2018
  • Loc: Minnesota USA

Posted 23 May 2019 - 01:03 AM

Noah,

When I was testing CPWI, I was not doing anything with Hyperstar. I was just using my 40mm for course adjustment and 9mm eyepieces for fine adjustment.

If I was just using CPWI for the first time, what are the steps in order to get a good alignment? I generally always use Star Sense Auto alignment using my hand control without adding any alignment points.


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: cassegrain, Celestron, EAA, mount, SCT



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics