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AP1200 CP3 declination backlash
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Tom Alderweireldt
Last year I acquired an older AP1200 CP3 mount, and upgraded it with the V2 chip to V4.19.3
Yesterday with moderate seeing, I ran the PHD2 guiding assistant and found out that the mount has approximately 380 msec declination backlash. While guiding quality due to seeing can be tuned, declination backlash doesn't. So that backlash value seems relatively high to me. How does that compare to other AP1200 mounts from similar generation? I don't have a clue wether this is high or low, or if I should try to tighten the declination motor? Hope the screenshot comes through in the list. Tom. |
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Hi Tom I can't speak for your comparative 1200 question, but in the big picture a 380ms backlash is small and easily handled in PHD2 with auto backlash compensation feature. By comparison you start getting into problems with backlash compensation around 1500ms+ Brian On Tue, Mar 28, 2023 at 8:36 AM Tom Alderweireldt <tom.alderweireldt@...> wrote: Last year I acquired an older AP1200 CP3 mount, and upgraded it with the --
Brian Brian Valente astro portfolio https://www.brianvalentephotography.com/astrophotography/ portfolio brianvalentephotography.com |
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astro-smart2016 <astro-smart2016@...>
Your tracking error in arc secs looks to be way over 1 arc sec. Are you balanaced and what is your load? Thats seems high for an ap mount. Just curious.
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Roland Christen
That amount is very low. Will not affect guiding whatsoever. Do not add backlash compensation in PHD2! Use 1x guide speed at all times. You have an excellent mount!!
Roland Christen
Astro-Physics Inc. -----Original Message-----
From: Tom Alderweireldt <tom.alderweireldt@...> To: main@ap-gto.groups.io Sent: Tue, Mar 28, 2023 5:35 am Subject: [ap-gto] AP1200 CP3 declination backlash Last year I acquired an older AP1200 CP3 mount, and upgraded it with the
V2 chip to V4.19.3
Yesterday with moderate seeing, I ran the PHD2 guiding assistant and
found out that the mount has approximately 380 msec declination backlash.
While guiding quality due to seeing can be tuned, declination backlash
doesn't.
So that backlash value seems relatively high to me. How does that
compare to other AP1200 mounts from similar generation?
I don't have a clue wether this is high or low, or if I should try to
tighten the declination motor?
Hope the screenshot comes through in the list.
Tom.
-- Roland Christen Astro-Physics |
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Looks almost exactly what I had after I self-serviced my 1200 CP3 and setting backlash according to the AP directions found on the internet. My first guiding graph looked like yours too! and I had about 300ms of backlash. I could not feel it when wiggling the camera end of the telescope.
Its an excellent result , take the advice given here and dont use the backlash compensation in Phd. |
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>>>Its an excellent result , take the advice given here and dont use the backlash compensation in Phd. I really do think auto backlash compensation in PHD2 is a good idea. Within PHD2 backlash compensation is adaptive, meaning it will adjust itself in real time to the amount of backlash correction needed. If it's very little or none, it will apply little to none. If it's more it will adjust accordingly Backlash can change with altitude as well Brian On Thu, Mar 30, 2023 at 8:53 PM Abraham <ashadbeh@...> wrote: Looks almost exactly what I had after I self-serviced my 1200 CP3 and setting backlash according to the AP directions found on the internet. My first guiding graph looked like yours too! and I had about 300ms of backlash. I could not feel it when wiggling the camera end of the telescope. --
Brian Brian Valente astro portfolio https://www.brianvalentephotography.com/astrophotography/ portfolio brianvalentephotography.com |
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Hmmm I thought the common advice was that it was to be left off but maybe this has been updated to be more advanced. Was it always adaptive?
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>>> I thought the common advice was that it was to be left off but maybe this has been updated to be more advanced. Was it always adaptive? It's been adaptive for quite some time (years) but I don't think people have been aware of it. "Traditional" guiding via original PHD, Maxim, etc. have not had adaptive, so it's a reasonable and conservative approach to avoid enabling it in other situations . Just to clarify, this isn't a general recommendation for all guiding software: Only PHD2 has adaptive backlash compensation And of course for an encoder mount (Mach 2, absolute encoders, etc.) you do not want to enable backlash compensation On Thu, Mar 30, 2023 at 9:18 PM Abraham <ashadbeh@...> wrote: Hmmm I thought the common advice was that it was to be left off but maybe this has been updated to be more advanced. Was it always adaptive? --
Brian Brian Valente astro portfolio https://www.brianvalentephotography.com/astrophotography/ portfolio brianvalentephotography.com |
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