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

Dithering issues

  • Please log in to reply
6 replies to this topic

#1 kevin.mcde

kevin.mcde

    Lift Off

  • -----
  • topic starter
  • Posts: 19
  • Joined: 24 May 2016
  • Loc: Norther New Mexico

Posted 07 March 2021 - 10:29 PM

Hello!

 

I've been using my smaller SV70T so long that when I pulled out my C9.25 last night there were...some issues to say the least. After using the smaller scope so much, I forgot how unforgiving the C9.25 can be. Between guiding, dithering, and calibration frame problems it was a long night.

 

My primary concern at the moment is the dithering.

With my SV70T, the communication with SharpCap and PHD2 is wonderful. I have it set to dither every 240 seconds and it works like a charm.

However, with the larger scope, dithering occurs but then it never starts capturing again. I suspect I have the dithering setting wrongs for a larger scope since it is less forgiving.

Setting are:

Dither interval: 240sec (I do 120 second shots so dithering after 2 shots, which has been fine for my smaller scope)

Max dither step: 20 pixels

Settle threshold: 3 pixels - I feel this could be an issue but not sure where to set it

Min settle time: 5 seconds

Max settle time: 60 seconds (max setting)

 

Any ideas on what I need to fix?

 

Thanks

Kevin



#2 AhBok

AhBok

    Mercury-Atlas

  • *****
  • Posts: 2,974
  • Joined: 02 Dec 2010
  • Loc: Lakeland, TN

Posted 08 March 2021 - 07:00 PM

I assume you are using an OAG with the same setup as the Apo? Are you using a .63x reducer?

#3 gcardona

gcardona

    Ranger 4

  • -----
  • Posts: 364
  • Joined: 24 Nov 2009

Posted 08 March 2021 - 07:06 PM

I suspect your settling threshold is too low for your SCT, and the guider can never settle to within 3 pixels.



#4 kevin.mcde

kevin.mcde

    Lift Off

  • -----
  • topic starter
  • Posts: 19
  • Joined: 24 May 2016
  • Loc: Norther New Mexico

Posted 08 March 2021 - 08:03 PM

I assume you are using an OAG with the same setup as the Apo? Are you using a .63x reducer?

No on axis guider. I am using a 0.63 reducer.



#5 kevin.mcde

kevin.mcde

    Lift Off

  • -----
  • topic starter
  • Posts: 19
  • Joined: 24 May 2016
  • Loc: Norther New Mexico

Posted 08 March 2021 - 08:04 PM

I suspect your settling threshold is too low for your SCT, and the guider can never settle to within 3 pixels.

That is high on my list. Just not sure what the setting should be.



#6 don314

don314

    Explorer 1

  • -----
  • Posts: 72
  • Joined: 10 Apr 2017

Posted 08 March 2021 - 09:33 PM

PHD2 instructions for Settling setting (as a starting point),  in PHD2 under "RMS Error:" it gives RA, Dec, Tot. errors in pixels followed by arc-seconds in parentheses.   Multiply the "Tot" Pixel value by 2, and enter result in "Settle at <  ?? Pixels".  I'm typically close to 0.45 pixels, so use a value of 1, seems to work OK for me. 



#7 kevin.mcde

kevin.mcde

    Lift Off

  • -----
  • topic starter
  • Posts: 19
  • Joined: 24 May 2016
  • Loc: Norther New Mexico

Posted 10 March 2021 - 08:40 PM

PHD2 instructions for Settling setting (as a starting point),  in PHD2 under "RMS Error:" it gives RA, Dec, Tot. errors in pixels followed by arc-seconds in parentheses.   Multiply the "Tot" Pixel value by 2, and enter result in "Settle at <  ?? Pixels".  I'm typically close to 0.45 pixels, so use a value of 1, seems to work OK for me. 

Thanks. If the clouds ever clear I'll give it a try.

Clouds...bangbang.gif   gaah.gif




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






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics