Jump to content


Photo

Mount Set up

  • Please log in to reply
7 replies to this topic

#1 Kalox

Kalox

    Lift Off

  • -----
  • Posts: 20
  • Joined: 01 Jun 2013

Posted 05 July 2013 - 11:00 AM

Hey guys,

I have a Celestron CGE 1400 out of which I want to get the most. So I have been reading quite a lot on the websites and got to know about backlash, PE and PEC, Cone error and other similar stuff. Right now however I would like (if possible) to sum up all the necessary (and possible) adjustments that I can make to the mount so that it is in perfect condition.

So far I have done the simplest things:
Balancing the mount in RA and DEC
Polar alignment
Leveled it with the ground

If anyone could just write and explain with a few sentences everything (really everything) that I can adjust or calibrate.

Thank you very much and I really hope someone can help, because I really want to get the mount into the best possible shape and from there - get excellent alignments and tracking and everything.

Kalox

#2 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15704
  • Joined: 06 Jul 2007

Posted 05 July 2013 - 01:28 PM

OK, but first we need to know why something needs to be "calibrated." What is wrong with the way the mount works now?

#3 Kalox

Kalox

    Lift Off

  • -----
  • Posts: 20
  • Joined: 01 Jun 2013

Posted 05 July 2013 - 03:49 PM

Well, the mount is working... ok. However I think it can always work better. Those are small imperfections with which I can live, but for instance after a 2+4 star alignment the star still doesn't come to the exact center of the eyepiece/camera (it is really close sometimes, but still not perfect).
Also, about the tracking - after maybe 15-20mins (maybe even less) there is a noticeable difference in the position of the star.
I'm pretty satisfied with the way the mount is performing at the moment, however I haven't done any calibrations or adjustments to the mount and that makes me think the mount could perform even better (maybe I'm wrong?).
I also want to ask a question that maybe is not exactly for this part of the forum, however:
I have an SBIG ST-2000XM CCD camera that I'm using with the scope and am trying to guide with it (through MaxIm DL 5). That turns out to be a bit of a problem for me - how do I know that the camera is guiding properly? I tried a couple of times but seems to me like I'm not doing something right.

Anyway, if anyone has any suggestion on any of those 2 topics, please share it with me.

Thanks!
Kalox

#4 Jesus Munoz

Jesus Munoz

    Ranger 4

  • -----
  • Posts: 365
  • Joined: 09 Mar 2007
  • Loc: Querétaro, México

Posted 05 July 2013 - 04:30 PM

Does the tracking after 15-20 minutes drifts the star visually? Maybe the problem is your polar alignment, speed of the motors or tracking rate. CGE mounts must perform better when properly polar aligned.

#5 CounterWeight

CounterWeight

    Cosmos

  • *****
  • Posts: 8213
  • Joined: 05 Oct 2008
  • Loc: Palo alto, CA.

Posted 05 July 2013 - 04:49 PM

The usual test of good guiding IMO is 'round stars' - if you are getting round stars you are good to go.

Drifting after the polar align usually just means the PA could be better.

Is your 14" setup in a permanent pier type setup or are you starting from scratch each time. Are you always using the same stars for you PA? Using a xhair illuminated reticle? Same tripod placement and care WRT time and co-ords? or maybe have the GPS module? I had very good results from both the original and ASPA with my CGE but that was with a C11 (and sometimes with a piggyback scope like the FS-102)

There is just too much that it could be if you are setting up new each time and doing things differently. My main advice is make no assumptions about anything with a heavy scope. Make certain you've minimized any possible source of flexing in the tripod and that it is on earth that wont compress (footpads for the legs help somewhat with that). Imaging takes no prisoners and long focal length imaging puts the bar up pretty high.

Yes the original CGE mount can be tinkered with heavily, but as Rod asked, the why may be more important than the what. There used to be some great threads on the Yahoo CGE group. Then you might ask Ed Thomas at Deep Space Products if you are set on tearing into it.

If you are transitioning from visual I recommend to start being far more rigorous in any methods and careful about any assumptions.

#6 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15704
  • Joined: 06 Jul 2007

Posted 06 July 2013 - 09:03 AM

Well, the mount is working... ok. However I think it can always work better. Those are small imperfections with which I can live, but for instance after a 2+4 star alignment the star still doesn't come to the exact center of the eyepiece/camera (it is really close sometimes, but still not perfect).


Wise words? "The Only Enemy of Good Enough is More Better." ;)

Tracking is dependent only on the quality of your polar alignment.

Well, if the stars come out round, you are guiding well. Another indication is that the guiding calibration in the CCDSoft or CCDOps software or whatever you are using completes successfully.

#7 Kalox

Kalox

    Lift Off

  • -----
  • Posts: 20
  • Joined: 01 Jun 2013

Posted 06 July 2013 - 11:31 AM

Ok, so... The mount is always on the same place - on the terrace. I don't disassemble it, don't move it don't do anything, so it's pretty much the same every time.
Unfortunately I have no eyepiece with an X, but I do the alignment with the camera actually, so I just put the X in MaxIm DL 5 and it's even better than with such an eyepiece (in my opinion). I have no GPS module - I thought of buying it but seems quite useless to me... for 222$...
Because the telescope is on the terrace I have just 180 degree view facing directly north (so I can see east, north west). I have done just the ASPA because everywhere I look for the drift method I always see that I have to point the telescope south (which I can't!) so... if anyone knows how to do it without looking south...
A question here is - should I be doing PA every time I start up the scope?? (I think not but...?)
In order to get the mount leveled I have to extend the legs of the mount a little bit and I'm concerned that although I have tightened the knobs the legs might have moved down a little bit. Any ideas here? Oh, the other thing is - I'm using the footpads, but they are quite old and because of the sun and really hot weather the orange substance has kinda melted... so I'm not sure if I should keep them or remove them...
Next thing is that in the following probably 2-3 months I don't see myself using eyepieces at all - I use the camera instead. So my setup is the same every time (more weight on the front - Hyperstar Lens + camera + dew shield) and nothing on the back really. In this case how should I go about the backlash and stuff like this? And actually I read that it is better to have the scope a little heavier on the one side... can someone please explain that - I mean to which side?
How do I calibrate the backlash and the other stuff...?(PEC and etc.) Also after alignment when should I sync to a star and how does that help?

Finally... I'm trying to use the camera's second chip as a guider, however I don't think it's working - I can't calibrate it (I get an error <5 Pixels in X or Y) and then I don't really know how to test if it's working properly (and I don't think it is)

Oh, so much work to be done... It's kind of frustrating sometimes when you're a beginner and start with such a scope :/ I'm attaching a 75sec picture so maybe you can get an idea of the results I get.

That was the first wave of questions, got more coming if anyone answers some of these...

Thanks very much guys, I really appreciate the help

Kalox

Attached Files



#8 scopefreak

scopefreak

    Viking 1

  • ****-
  • Posts: 806
  • Joined: 14 Apr 2004
  • Loc: Mayslick KY

Posted 08 July 2013 - 05:51 PM

I would have to say that if that image you posted was really 75" then your PA is pretty close to being right on the money. All the stars look nice and round and I cant really detect any streaking.

Stop worrying about perfection and enjoy the hobby :tonofbricks:. You have nice equipment and it looks like you are on your way.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics