Jump to content


Photo

First equatorial mount questions

  • Please log in to reply
23 replies to this topic

#1 foste1cc

foste1cc

    Vostok 1

  • -----
  • Posts: 154
  • Joined: 06 Jan 2013
  • Loc: Armada, MI

Posted 30 January 2013 - 06:01 PM

hey everyone, i'm looking into buying my first equatorial mount for AP. I'm not looking into getting anything extremely fancy or pricey yet, just something that can polar align and track well for AP. As of now, i have a SCT 8SE on an Alt/Az mount and i know trying this setup for AP would be a headache and a half with the field rotation and poor gear design. would the celestron CG5-GT be a decent mount to start out with? I don't have anything over a $1,000, preferably i'd like to spend more like $700-ish range. I noticed Meade makes a similar mount, and i've seen more for under a grand. I was thinking of possibly buying used for nicer mounts if they're not too much $ if you guys think that'd be the way to go. but all input and advice is welcome! i'm a newbie with AP and equatorial mounts. So what do you guys think?? thanks in advance!

Carl

#2 mega256

mega256

    Viking 1

  • *****
  • Posts: 925
  • Joined: 10 May 2007
  • Loc: N of Tampa

Posted 30 January 2013 - 06:23 PM

Used may well be the best way for you to go!
Iv seen many Atlas/EQ6 mounts used that are around
$900.I would highly recomend this because there
is alot of info and parts for this mount.It would do
a good job with your C8.Just keep your eye out and try
to find a newer one.There will be less to work on,if
needed with one just a few years old or less.The Atlas
come up alot on this site and am.The mount is built heavy duty and alot can be done with mods if you like.It will handle a bigger scope if you decide to get one latter.
Also EQmod software is free and works with this mount.

#3 neptun2

neptun2

    Viking 1

  • -----
  • Posts: 858
  • Joined: 04 Mar 2007
  • Loc: Bulgaria

Posted 30 January 2013 - 08:37 PM

Used Atlas is a good idea. You can also get Atlas's scaled down version - sirius (heq5 pro) for 1119$ but this will maybe be too much for your budget. I have HEQ5 Pro mount and am happy with it. It has the same software like the Atlas but the capacity is lower (20 kg for atlas and 14 for sirius).

#4 WarmWeatherGuy

WarmWeatherGuy

    Surveyor 1

  • *****
  • Posts: 1904
  • Joined: 27 Aug 2011
  • Loc: Orlando, FL 28° N, 81° W

Posted 30 January 2013 - 09:46 PM

I would look into the new Celestron Advanced VX mount.

You can buy the mount by itself from Astronomics:
https://www.astronom...al-telescope...
Be sure to mention your Cloudy Nights account name for a possible discount.

This YouTube video shows you the mount.
http://www.youtube.c...h?v=AiKDoxjmtmU

#5 foste1cc

foste1cc

    Vostok 1

  • -----
  • Posts: 154
  • Joined: 06 Jan 2013
  • Loc: Armada, MI

Posted 31 January 2013 - 06:36 AM

thanks guys! this is helping a bunch! i'll only have my 8SCT and a T2i attached to the mount for now, but plan on getting a guiding scope and orions autoguider. Would the sirius hold this weight?? i'm going to start looking at used deals now.

Carl

#6 CJK

CJK

    Viking 1

  • -----
  • Posts: 555
  • Joined: 05 Dec 2012
  • Loc: Northeast TN

Posted 31 January 2013 - 07:18 AM

You'd be getting close to the maximum rated weight for the Sirius/HEQ5 Pro with your OTA alone. If I were you, I'd be looking for a used Atlas instead -- for AP, it's always better to have too much mount than too little.

-- Chris

#7 neptun2

neptun2

    Viking 1

  • -----
  • Posts: 858
  • Joined: 04 Mar 2007
  • Loc: Bulgaria

Posted 31 January 2013 - 07:32 AM

Sirius is rated for 14 kg payload but this is for visual. My experience shows that you should not go over 10kg for photography. For 8" SCT together with dslr and guide scope it will be ok but if you manage to get used Atlas for the same price of course it will be better.

#8 CJK

CJK

    Viking 1

  • -----
  • Posts: 555
  • Joined: 05 Dec 2012
  • Loc: Northeast TN

Posted 31 January 2013 - 07:36 AM

FWIW, the OP's 8SE is listed at 24 lbs (10.8 kg) on the Celestron web site.

-- Chris

#9 EFT

EFT

    Vendor - Deep Space Products

  • *****
  • Vendors
  • Posts: 2545
  • Joined: 07 May 2007
  • Loc: Phoenix, AZ

Posted 31 January 2013 - 09:31 AM

If you are just starting out, the new Celestron VX would be OK but there are a few things that you should do. Get a small refactor (70-80mm) to mount on top of the C8. Start imaging using the refractor for imaging and the C8 for guilding. When you get that down, then switch to using the refractor for guiding and image with a focal reducer on the C8. Once you get that down, then try prime focus imaging on the C8.

Starting out at prime focus on the C8 will likely be very frustrating because it will push the mount very far towards it limits. SCT imaging is just plain difficult. Also, do not plan on imaging without guiding, it's just a waste of time.

The downside of starting with this mount is that you are really at the max with the C8 so if you want to move up in apature you will need a larger mount. However, the mount should do very well with lighter scopes like refractors and there is a lot that can be done that way.

A used CGEM or Atlas would be better but will cost you around $1000 plus shipping.

Meade has nothing to offer at this point.

#10 foste1cc

foste1cc

    Vostok 1

  • -----
  • Posts: 154
  • Joined: 06 Jan 2013
  • Loc: Armada, MI

Posted 31 January 2013 - 04:07 PM

awesome info guys! thanks again! do any of you know if the Atlas or CGEM would be a better investment?? both seem to be pretty similar..

#11 WarmWeatherGuy

WarmWeatherGuy

    Surveyor 1

  • *****
  • Posts: 1904
  • Joined: 27 Aug 2011
  • Loc: Orlando, FL 28° N, 81° W

Posted 31 January 2013 - 04:44 PM

You will find that you're always overloading your mount. The C8 will only be half of the weight, or less. You need a guide scope. If you want to take images at 2000mm then your guide scope probably should be long too. I use a C5 to guide my C8. That adds weight. Then you need to connect the two. I use a side-by-side bar that weighs 6 pounds. My camera weighs 2 pounds. There are dew shields and heat strips. All that combined pretty much maxes out my CGEM.

So to answer your question, yes, I think the Atlas or CGEM would be a better investment. The VX should be good for mounting a pair of 3 to 4 inch refractors. There are plenty of targets that require such scopes so you don't really need to be imaging at 2000mm. But, if you get the VX and decide that you want to image a small galaxy then you'll wish you had a heavier mount.

This book

The 100 Best Astrophotography Targets
http://www.amazon.co...s/dp/1441906029

will give you an idea of what scope is used for what targets.

#12 EFT

EFT

    Vendor - Deep Space Products

  • *****
  • Vendors
  • Posts: 2545
  • Joined: 07 May 2007
  • Loc: Phoenix, AZ

Posted 31 January 2013 - 04:49 PM

awesome info guys! thanks again! do any of you know if the Atlas or CGEM would be a better investment?? both seem to be pretty similar..


It is very much a toss up. There are some improvement on the CGEM that I think are important including the counterwieght bar and latitude adjustment, but those are the main thing. My personal preference is for the CGEM, but I am a visual person, not an imager, and some imagers prefer the Atlas because of EQMOD. Perhaps the biggest advantage to the CGEM is if you are looking to buy a scope as well since Celestron offers some excellent deals on combinations. If you are looking at used, be aware that Orion will not service used equipment whereas Celestron will.

#13 CJK

CJK

    Viking 1

  • -----
  • Posts: 555
  • Joined: 05 Dec 2012
  • Loc: Northeast TN

Posted 31 January 2013 - 04:55 PM

If you are looking at used, be aware that Orion will not service used equipment whereas Celestron will.


Which is incredibly bizarre, since both are owned by Synta. :scratchhead:

-- Chris

#14 EFT

EFT

    Vendor - Deep Space Products

  • *****
  • Vendors
  • Posts: 2545
  • Joined: 07 May 2007
  • Loc: Phoenix, AZ

Posted 31 January 2013 - 05:48 PM

If you are looking at used, be aware that Orion will not service used equipment whereas Celestron will.


Which is incredibly bizarre, since both are owned by Synta. :scratchhead:

-- Chris


Synta owns Celestron but no Orion. Orion simply sells equipment that is manufactured by Synta.

#15 ourobouros2k2

ourobouros2k2

    Messenger

  • -----
  • Posts: 489
  • Joined: 10 Nov 2011
  • Loc: okc area, oklahoma

Posted 01 February 2013 - 12:15 PM

I don't know why celestron.com lists "telescope weight" as 24lbs. Must be including the mount because my 8SE OTA is aroudn 12 pounds. Well it was before the telrad, los-d rail, and 80mm guidescope/cam. Now it clocks in at about 18.5

#16 foste1cc

foste1cc

    Vostok 1

  • -----
  • Posts: 154
  • Joined: 06 Jan 2013
  • Loc: Armada, MI

Posted 01 February 2013 - 04:47 PM

I agree about the weight. there's no way my OTA weighs that much by itself. Being about 12lbs, do you guys think i could get away with getting a celestron VX for my first mount? i'd get orions autoguiding package soon after, but i feel like that only add a couple pounds max. What can't the VX do that others like the Atlas and CGEM do besides the weight difference??

#17 ourobouros2k2

ourobouros2k2

    Messenger

  • -----
  • Posts: 489
  • Joined: 10 Nov 2011
  • Loc: okc area, oklahoma

Posted 01 February 2013 - 08:03 PM

VX is new so not sure how it stacks up yet, but since it has cg-5 heritage in it's design balancing slightly east heavy it should do ok. I am having balance issues with sirius eq-g and c8/guidescope combo, but that will be remedied with a counterweight extension bar.

#18 aberrs

aberrs

    Sputnik

  • -----
  • Posts: 44
  • Joined: 23 Aug 2011

Posted 05 February 2013 - 12:34 AM

You might save some weight by using an OAG rather than a guide scope. But in either case I agree with Ed that starting through a smallish refractor is a good way to go.

#19 orlyandico

orlyandico

    Fly Me to the Moon

  • *****
  • Posts: 5491
  • Joined: 10 Aug 2009
  • Loc: Singapore

Posted 05 February 2013 - 12:51 AM

One issue with OAG is that it places much more stress on your focuser.

#20 JMW

JMW

    Apollo

  • -----
  • Posts: 1414
  • Joined: 11 Feb 2007
  • Loc: Nevada

Posted 05 February 2013 - 01:25 AM

Starting out I would say buy a used Atlas and put a used 80mm ED scope on it. You will find that a 600mm focal length scope is much less frustrating than starting out at 2000mm using your F10 SCT with a shifting mirror. Longer focal length means everything has to be much more precise to keep your stars looking round.

Once you master drift aligning for polar alignment, balancing your mount and auto-guiding you will be ready to try imaging with your 8 inch SCT. Because SCT mirrors can shift as the scope follows the stars through the sky an off axis guider is a good way to improve the benefits of auto-guiding.

#21 Raginar

Raginar

    Fly Me to the Moon

  • *****
  • Posts: 6138
  • Joined: 19 Oct 2010
  • Loc: Rapid CIty, SD

Posted 05 February 2013 - 10:17 AM

One issue with OAG is that it places much more stress on your focuser.

+1. It can introduce issues through flexure as well.

#22 orlyandico

orlyandico

    Fly Me to the Moon

  • *****
  • Posts: 5491
  • Joined: 10 Aug 2009
  • Loc: Singapore

Posted 05 February 2013 - 10:36 AM

i mention the OAG focuser flexure issue because i used an OAG for a while.

the focuser sagged a tiny bit which caused the CCD sensor to become non-orthogonal to the image plane. net result - stars were oblong on one side of the image.

the only way to address focuser sag is a pricey Feathertouch focuser. that focuser alone is 400 bucks - as much as a used CG5 mount.

i went back to guide scope, because i wasn't willing to pony up for the Feathertouch.

#23 neptun2

neptun2

    Viking 1

  • -----
  • Posts: 858
  • Joined: 04 Mar 2007
  • Loc: Bulgaria

Posted 05 February 2013 - 11:06 AM

Well i personally never had problems with focuser load and OAG and my scopes used pretty standard focusers. My load is nikon d90 dslr , flattener/coma corrector , TS 9mm off-axis guider and meade dsi 2 pro. The whole weight is around 1.2 kg. I used it on both my 8" newtonian and now on my 120 ed refractor without any problem. The newtonian was relatively old skywatcher model from 2008 and used pure rack and pinion focuser without fine focus adjustment. The refractor is with dual speed crayford with relatively long travel distance. Of course it is possible that some combinations of of focuser and accessories can cause such ortogonality problems but it is not so common and not always needed to go with feathertouch to avoid it.

#24 orlyandico

orlyandico

    Fly Me to the Moon

  • *****
  • Posts: 5491
  • Joined: 10 Aug 2009
  • Loc: Singapore

Posted 05 February 2013 - 11:27 AM

i had a much bigger OAG than the TS9. this caused a longer moment arm.

the TS9 isn't exactly cheap, either..

but you won't know till you try. the problem with AP is that when you solve one problem (the biggest enemy of star roundness is the mount) some other factor comes in.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics