Backlash


Mike Dodd
 

On 3/14/2021 5:28 PM, Tom Blahovici wrote:
I have this mount and use it for imaging.
Which mount would that be?

I have backlash of 2 seconds in Dec....
My mount had a 2.8 arc second peak to peak periodic error without PEC.
Periodic error has nothing to do with Dec, only RA. If your mount requires Dec corrections, that indicates your polar alignment should be adjusted.

Dec adjustments should be infrequent. Do your Dec corrections need the same 2-second backlash in both directions, or only one? IOW, is the correction with the backlash the same in both directions?

If so, it sounds to me like your work-to-worm-wheel mating is too loose, and needs adjusting. If not, that sounds like a balance issue, which would manifest itself only while pointing to certain areas of the sky.

--- Mike


Tom Blahovici
 

I have this mount and use it for imaging. Balance seems to be really important but a bit difficult to do.
I have backlash of 2 seconds in Dec and when I image with Voyager, it takes a couple of starts to get rid of it. Once gone there is no issue.
It is actually a really nice mount and is rock solid for my FSQ106 with Moonlite Nitecrawler and camera setup.  Certainly better than a Losmandy G11 I used to have.
In any case, it is not difficult to adjust the backlash but does take a while. There's a manual on this on the AP website.
My mount had a 2.8 arc second peak to peak periodic error without PEC.
Tom


thefamily90 Phillips
 

Fantastic! No imaging planned.
Thank you!

JimP


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Roland Christen via groups.io <chris1011@...>
Sent: Sunday, March 14, 2021 3:41:46 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Backlash
 
Backlash will be on the order of arc second, so it realistically won't have any effect on pointing. It can also be mitigated on that mount with careful adjustment, however it is really only important if you want to image and guide during imaging.

Roland



-----Original Message-----
From: thefamily90 Phillips <thefamily90@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Sun, Mar 14, 2021 2:10 pm
Subject: [ap-gto] Backlash

Thinking about purchasing an AP 600 E GOTO for visual observations of double stars with my AP 155 F/7. Everything about the Mount sounds good except the seller says it has significant declination backlash. As I will be using the GOTO function and searching for doubles using the RA/DEC coordinates on the keypad I am concerned about being able to align properly using 2-3 stars. Here’s what I found. Any thoughts 

JimP
Image.jpeg



--
Roland Christen
Astro-Physics


Roland Christen
 

Backlash will be on the order of arc second, so it realistically won't have any effect on pointing. It can also be mitigated on that mount with careful adjustment, however it is really only important if you want to image and guide during imaging.

Roland



-----Original Message-----
From: thefamily90 Phillips <thefamily90@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Sun, Mar 14, 2021 2:10 pm
Subject: [ap-gto] Backlash

Thinking about purchasing an AP 600 E GOTO for visual observations of double stars with my AP 155 F/7. Everything about the Mount sounds good except the seller says it has significant declination backlash. As I will be using the GOTO function and searching for doubles using the RA/DEC coordinates on the keypad I am concerned about being able to align properly using 2-3 stars. Here’s what I found. Any thoughts 

JimP
Image.jpeg



--
Roland Christen
Astro-Physics


thefamily90 Phillips
 

Thinking about purchasing an AP 600 E GOTO for visual observations of double stars with my AP 155 F/7. Everything about the Mount sounds good except the seller says it has significant declination backlash. As I will be using the GOTO function and searching for doubles using the RA/DEC coordinates on the keypad I am concerned about being able to align properly using 2-3 stars. Here’s what I found. Any thoughts 

JimP
Image.jpeg