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

AP 1100GTO without encoders

  • Please log in to reply
11 replies to this topic

#1 Bobo666

Bobo666

    Lift Off

  • -----
  • topic starter
  • Posts: 2
  • Joined: 17 Nov 2020

Posted 22 November 2020 - 02:28 AM

Having decided this mount ticks all my criteria for a mount, I was just wondering how many use it without encoders?

 

Would I be correct in suggesting that with encoders the advantages are:

1. slight increase in tracking/guiding performance which in real life would be negligible,

2. short unguided exposures are possible as opposed to impossible without encoders.

 

Any other differences with/without encoders?

 

Thanks in anticipation.

 

Rob



#2 MJB87

MJB87

    Surveyor 1

  • *****
  • Moderators
  • Posts: 1,945
  • Joined: 17 Feb 2014
  • Loc: Talbot County, MD & Washington, DC

Posted 22 November 2020 - 03:17 AM

Short unguided imaging -- certainly at least up to several minutes -- is easily done on a 1100GTO lacking encoders, if the mount is accurately polar aligned.

 

There is a discussion of the benefits of absolute encoders (on a different AP mount) here:

 

https://www.astro-physics.com/mach2gto



#3 R Botero

R Botero

    Mercury-Atlas

  • -----
  • Posts: 2,823
  • Joined: 02 Jan 2009
  • Loc: Kent, England

Posted 22 November 2020 - 04:15 AM

Rob

I’ve had an 1100GTO w/o encoders since 2014. It just works. Guides very well throughout the sky. I’m imaging at 1300mm with a 6” refractor (now I have a tandem setup alongside it with a smaller refractor doing OSC only). Once balanced and with a proper PE calibration it just fades into the background. I’ve done only two PE curves since I’ve had it.
I have it in my backyard RoR permanently mounted. I only polar aligned when I put it there. Encoders wouldn’t really have helped me much more in my permanent setup. With APCC I can control all tracking limits both for meridian and horizon and regularly image with counterweights up in an automated manner using Voyager.

You can’t go wrong with an AP mount. Good luck!

Roberto

Edited by R Botero, 22 November 2020 - 04:17 AM.

  • RogerLaureys and mikela like this

#4 John O'Grady

John O'Grady

    Viking 1

  • *****
  • Posts: 538
  • Joined: 15 Nov 2009
  • Loc: Waterloo, ON CAN

Posted 22 November 2020 - 06:20 PM

I had my AP1100GTO  for ~1 year before I purchased the encoders.  For me the encoders add some (marginal) value  specifically:

  • Under strong wind conditions it really makes a difference if imaging with a sail (i.e. large SCT with a dew shield)
    • Mind you, without the encoders the mount withstood quite strong winds (but it won't self-correct if there is movement like it will with the encoders).
  • Periodic error is eliminated 
  • No need to waste time capturing and programming PEC

 

IMHO, for my skies I would recommend going without encoders to save money.

But I would recommend investing in APCC Pro.  The ability to go unguided is phenomenal.

And it's been my experience that the APPC Pro adds considerable value.

I still run a guider, mostly as a safety and to check on seeing and to verify the model & polar alignment are good.


Edited by John O'Grady, 23 November 2020 - 12:05 PM.

  • tjugo likes this

#5 Bobo666

Bobo666

    Lift Off

  • -----
  • topic starter
  • Posts: 2
  • Joined: 17 Nov 2020

Posted 23 November 2020 - 02:41 AM

Thank you all for your invaluable replies. I feel much happier going without encoders now.

 

Cheers



#6 MJB87

MJB87

    Surveyor 1

  • *****
  • Moderators
  • Posts: 1,945
  • Joined: 17 Feb 2014
  • Loc: Talbot County, MD & Washington, DC

Posted 23 November 2020 - 08:05 AM

You will love the 1100GTO! As has been said above, you just don't worry about it. It just simply works.

 

My only recommendation is to buy a very high quality spirit level so you can put the setup in one of the pre-established park positions with great accuracy.  



#7 John Vogt

John Vogt

    Mariner 2

  • *****
  • Posts: 215
  • Joined: 26 Oct 2005

Posted 23 November 2020 - 08:49 AM

I had my AP1100GTO  for ~1 year before I purchased the encoders.  For me the encoders add some (marginal) value  specifically:

  • Under strong wind conditions it really makes a difference if imaging with a sail (i.e. large SCT with a dew shield)
    • Mind you, without the encoders the mount withstood quite strong winds (but it won't self-correct if there is movement like it will with the encoders)

Do the encoders reduce image shake under windy conditions or while focusing for visual use?

 

Thx,

John



#8 John O'Grady

John O'Grady

    Viking 1

  • *****
  • Posts: 538
  • Joined: 15 Nov 2009
  • Loc: Waterloo, ON CAN

Posted 23 November 2020 - 09:27 AM

Do the encoders reduce image shake under windy conditions or while focusing for visual use?

 

Thx,

John

Absolutely, it (near) immediately corrects for shakes due to windy conditions.  But why take my word for it when you can hear Roland from Astro-physics explain it and see it demonstratated in this video.  Watch from the timestamp included for at least 30 seconds.

 

Focusing may be a different matter if you have a scope with differential flexure or mirror flop.  The mount can't correct for a source of mechanical shift that's beyond it's control.

But the encoders will help to force the mount back into a precise position as a result of being nudged during focusing. 

 

Also, for anyone using plate solving for imaging.  Imagine a mount that once properly aligned (sync'ed) going precising to the coordinates and only occassionally needing to do a second plate solve.

That's another nice feature which I was seeing even before I upgraded to absolute encoders. [EDIT] And that's imaging at ~0.5 arcseconds/per pixel with a C9 reduced to F7.


Edited by John O'Grady, 23 November 2020 - 12:07 PM.


#9 JMW

JMW

    Skylab

  • -----
  • Posts: 4,038
  • Joined: 11 Feb 2007
  • Loc: Nevada

Posted 23 November 2020 - 07:45 PM

I have the AP900GTO with an upgrade to the CP4 controller. It is on a concrete pier well aligned. I have done unguided exposures without issue when using a 800mm focal length refractor. I use PHD2 because it is easy to guide with and I am now using an f/4 10 inch newtonian on the mount.

 

I am on the Mach 2 and AP1100 waiting list. I am leaning on getting the AP1100 for the 110 pound imaging capacity. I want to add a 2nd imaging camera and scope to my observatory rig and my AP900 is at its limit with the f/4 10 inch newtonian.

 

I plan to keep the AP900 and use it for star party imaging with lighter setups such as refractors or C11 Edge HD. 

 

The Mach 2 is a great price for encoders but I think with PHD2 guiding and ASPAT plate solving the AP1100 will do great. I am mostly using backyard observatory for EAA or doing narrowband imaging to overcome light pollution. I can do dark sky imaging with my lighter setup at star parties.


Edited by JMW, 24 November 2020 - 01:40 PM.

  • RogerLaureys and R Botero like this

#10 andysea

andysea

    Skylab

  • *****
  • Posts: 4,200
  • Joined: 03 Sep 2010
  • Loc: Seattle, WA

Posted 24 November 2020 - 02:27 PM

I think it also depends on what kind of imaging one wants to do. I will eventually upgrade to the 1100 with encoders but it will be a marginal benefit for me.

Most of my imaging is wide field and the native PE of my AP900 is 4" P-P.

The encoders in my case will probably only offer a very small improvement because for the most part I use the FSQ at f3 or the Epsilon 130.

Maybe they will help with the GTX if I use it consistently.



#11 JMW

JMW

    Skylab

  • -----
  • Posts: 4,038
  • Joined: 11 Feb 2007
  • Loc: Nevada

Posted 24 November 2020 - 03:55 PM

I was working on my AP900 this week setting up changes in the imaging rig. I decided it was time to replace the keypad battery. I called up Astro-Physics and ordered the replacement battery kit along with a grease kit. I have had a trouble free mount but after 9 years it was probably overdue.



#12 MHamburg

MHamburg

    Vanguard

  • *****
  • Posts: 2,129
  • Joined: 21 Jun 2006
  • Loc: Brooklyn, NY/Berkshires, MA

Posted 25 November 2020 - 10:30 AM

I absolutely love my AP900. It's a joy to see how well it works with PHD2. That guide star doesn't have a chance to run away. 

Michael 




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