Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Mounts

Pages: 1 | 2 | (show all)
SkipW
sage


Reged: 02/03/11

Loc: Oklahoma, USA
Re: CG-5 slewing arrows - Need Help!!!! new [Re: James Cunningham]
      #4537875 - 04/22/11 11:24 PM

Again, sorry for the confusion. Just remember, pressing the up and down arrows rotate the scope north and south (not necessarily up and down), and the left and right arrows move it in decreasing and increasing RA. Best is just to try it and see. The highest-speed slewing makes it possible to see what is actually happening.

Post Extras: Print Post   Remind Me!   Notify Moderator  
solshaker
Carpal Tunnel
*****

Reged: 06/06/06

Re: CG-5 slewing arrows - Need Help!!!! new [Re: James Cunningham]
      #4537883 - 04/22/11 11:28 PM

Quote:

Thanks to all for first clarifying everything and then confusing me all over again.




.sorry man, but thats funny.

dont sweat wrapping your head around the eq mount. it will take a few sessions to get an intuitive feel moving it about. thats a great idea to set up in the garage with the scope pointing north and just loosen the clutches and practice pointing at where saturn and other bright objects would be. better yet, do it outside and use saturn, the moon and stars like sirius and arcturus to practice moving the mount around (be sure to properly balance the mount and the scope should move smoothly and not get away from you). sighting down the tube and using a finder helps.

when you (finally) get an object in the ep, lock the clutches and let the mount track and fool with the buttons and youll soon figure out the directions. after a while youll get the hang of it and the celestial sphere will make sense in relation to the mount.

it took me quite a few sessions to get efficient and "accurate". once you get it down, its easy.


Post Extras: Print Post   Remind Me!   Notify Moderator  
James Cunningham
Post Laureate
*****

Reged: 08/07/10

Loc: Maryland
Re: CG-5 slewing arrows - Need Help!!!! new [Re: solshaker]
      #4538209 - 04/23/11 07:11 AM

You say "when you (finally) get an object in the ep, lock the clutches and let the mount track"
I had no idea that if I get something within the eyepiece by slewing with the buttons that it would track whatever is in the eyepiece. How will the mount know to track that object?


Post Extras: Print Post   Remind Me!   Notify Moderator  
rmollise
Postmaster
*****

Reged: 07/06/07

Re: CG-5 slewing arrows - Need Help!!!! new [Re: James Cunningham]
      #4538319 - 04/23/11 08:44 AM

Quote:

So the RA is controlled by the arrows pointing up and down and the Dec is controlled by the arrows pointing side to side? Have I got that right?




Nope...you are still Bassackwards.


Post Extras: Print Post   Remind Me!   Notify Moderator  
James Cunningham
Post Laureate
*****

Reged: 08/07/10

Loc: Maryland
Re: CG-5 slewing arrows - Need Help!!!! new [Re: rmollise]
      #4538326 - 04/23/11 08:48 AM

Yeah, someone corrected me earlier in a post. Thanks.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Midnight Dan
Postmaster
*****

Reged: 01/23/08

Loc: Hilton, NY, Yellow Zone (Bortl...
Re: CG-5 slewing arrows - Need Help!!!! new [Re: James Cunningham]
      #4538384 - 04/23/11 09:24 AM

Quote:

You say "when you (finally) get an object in the ep, lock the clutches and let the mount track"
I had no idea that if I get something within the eyepiece by slewing with the buttons that it would track whatever is in the eyepiece. How will the mount know to track that object?




Hi James:

The whole purpose of a GEM mount is to align it's axes with the how the sky rotates so that when the RA axis moves, it will track whatever the scope it pointing at.

Think of it like this. Open an umbrella, hold it out at arms's length, and point it at the North Star. Paint a bunch of stars on the inside of it and slowly rotate it. The stars you painted on it are now moving in a circle around the North Star. This is the way the sky moves (actually the Earth is moving, but the sky appears to move). If one of the stars you painted lined up with a real star, and if you spun the umbrella at the right speed, you'd be tracking that star across the sky.

Now if you take a mount and align the RA axis with the North Star, you've done the same thing as pointing the umbrella at it. If you spin the mount around the RA axis at the right speed, it will move in exactly the same way that the sky does.

Moving the Declination axis is like focusing your gaze closer to the center of the umbrella, or father away from the center. If you move the Dec axis so that your scope is aiming at a star at the edge of our fictitious umbrella, you can now leave the Dec axis alone, and simply moving the RA axis at the right speed will track the object.

So the point is, after the mount is polar aligned, you can point the scope anywhere you like. The RA axis just continues to rotate at the same speed as the sky and whatever object you're pointing at will be tracked.

As for the buttons, again think of the umbrella. Moving the up/down buttons moves the scope closer to the center of rotation or farther away (Declination). Moving the left/right buttons will rotate the scope around the North Star one way or the other (Right Ascension). When you are not using any buttons, but the mount is in tracking mode, it is simply moving the RA axis so it rotates around the North Star at the same speed as the sky.

Hope this helps!

-Dan


Post Extras: Print Post   Remind Me!   Notify Moderator  
James Cunningham
Post Laureate
*****

Reged: 08/07/10

Loc: Maryland
Re: CG-5 slewing arrows - Need Help!!!! new [Re: Midnight Dan]
      #4538497 - 04/23/11 10:47 AM

I made a cheat sheet to take with me the next time I go out after slewing in the garage this morning. Take a look and give me your thoughts.

1. Level the scope

2. Find alignment stars beforehand

3. Make sure GPS has linked

4. Try to go up and then to the right to align

5. On GEM: Think North - South & East - West and not up and down or side to side

Dec - The up/down buttons slew you toward or away from Polaris (up = toward down = away).
RA - The left/right buttons slew in a circle around Polaris (right = counterclockwise left = clockwise).
From North - Up arrow slews left and down
Down arrow slews right and down
Right arrow circles to left and down
Left arrow circles to the left and up

From East - Up arrow slews down and to left
Down arrow slews up and to the right
Left arrow slews up
Right arrow slews down

From South - Up arrow slews left
Down arrow slews right and down
Left arrow slews down
Right arrow slews slews up and to the right
Left arrow slews slews down

From West - Up arrow slews down and left
Down arrow slews up and right
Left arrow slews up and right
Right arrow slews downward

6. Defocus the star just a little when aligning


Post Extras: Print Post   Remind Me!   Notify Moderator  
nganga
super member


Reged: 03/16/08

Re: CG-5 slewing arrows - Need Help!!!! new [Re: James Cunningham]
      #4544177 - 04/25/11 10:03 PM

Quote:

I made a cheat sheet to take with me the next time I go out after slewing in the garage this morning. Take a look and give me your thoughts.






You could use a cheatsheet, but it will probably turn out easiest to just do it. One thing that might make life a lot easier is to align the eyepiece reticle lines with the OTA. Then your alignment star moves in the same direction as the reticle lines. You are trying to bring an alignment star into the intersection of the reticle lines. If you hit the wrong button, you will see that immediately and make the necessary change.

Up and right buttons are the final steps to center the star.

The first alignment star will probably be way off, especially if you set up afresh at every session, but once you center that in your finderscope or RDF and then align at the eyepiece, the subsequent stars will be closer to where you want them to be.

Hope that helps.

Clem


Post Extras: Print Post   Remind Me!   Notify Moderator  
dwitek
sage
*****

Reged: 07/03/08

Loc: White Lake, Michigan
Re: CG-5 slewing arrows - Need Help!!!! new [Re: nganga]
      #4545828 - 04/26/11 03:54 PM

I've always wondered why the first alignment star is so far off. I mean, I do a pretty good polar alignment by hand now but no matter where the first alignment star is it's usually at least 5 to 10 degrees off.

Post Extras: Print Post   Remind Me!   Notify Moderator  
PHampson
sage


Reged: 10/25/05

Loc: Nashville, TN
Re: CG-5 slewing arrows - Need Help!!!! new [Re: dwitek]
      #4545985 - 04/26/11 04:45 PM

Once you have a good alignment and have finished a session, rather than just shut down, put the scope in hibernate mode. This will store the existing alignment so when you restart, it should be pretty close when you realign for your next session. That's the only way I found to change the settings the mount came with which were off by a fair bit. Once you have it reset pretty well, you can skip the hibernate and just shut down like usual.
Good luck.

Paul


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jim Curry
Pooh-Bah
*****

Reged: 10/29/07

Loc: STL
Re: CG-5 slewing arrows - Need Help!!!! new [Re: PHampson]
      #4547202 - 04/27/11 07:36 AM

James:
I would suggest setting up just after sunset. Aim the polar axis roughly towards Polaris. Point the scope towards the west and press all 4 buttons while watching the scope move and pay attention to which axis is rotating (don't stick your eye in the eyepiece at this point). Move the scope to the 3 other cardinal points and press the buttons again watching how the scope is moving and which axis is rotating. As the sky darkens and stars start popping out go to your eyepiece and watch how a star moves across the field for a given button. Sometimes in the dark you'll want to give the scope a gentle hand nudge in the direction you want to go before pressing a button.

Jim


Post Extras: Print Post   Remind Me!   Notify Moderator  
spencerj
Pooh-Bah
*****

Reged: 11/17/04

Loc: Londonderry, NH
Re: CG-5 slewing arrows - Need Help!!!! new [Re: dwitek]
      #4547919 - 04/27/11 02:55 PM

Quote:

I've always wondered why the first alignment star is so far off. I mean, I do a pretty good polar alignment by hand now but no matter where the first alignment star is it's usually at least 5 to 10 degrees off.




Yeah. That part of the OP's post has gotten overlooked. He said . . .

"I got Polaris in the Polar scope, think I had the scope level and then pressed the button to slew to the first alignment star. There were several stars visible so I picked the brightest one for alignment."

Ah . . . that is not going to work. The CG-5 mount is really a decent mount, but the first alignment star is not going to be in the FOV of the eyepiece. You have to move the scope to the star you said you were aligning to--even if it is not in the FOV. If you are aligning on Regulus, you have to point to Regulus, not just the "brightest" star in a random group the mount happens to point to.

Get out your star atlas and do a reality check. Make sure you are aligning on what you say you are aligning on. You will then have better luck slewing to Saturn and all other targets.


Post Extras: Print Post   Remind Me!   Notify Moderator  
James Cunningham
Post Laureate
*****

Reged: 08/07/10

Loc: Maryland
Re: CG-5 slewing arrows - Need Help!!!! new [Re: spencerj]
      #4547924 - 04/27/11 02:59 PM

That is exactly what I plan to do next time. Find some stars beforehand to align on.

Post Extras: Print Post   Remind Me!   Notify Moderator  
James Cunningham
Post Laureate
*****

Reged: 08/07/10

Loc: Maryland
Re: CG-5 slewing arrows - Need Help!!!! new [Re: James Cunningham]
      #4551264 - 04/29/11 09:44 AM

A friend came over last night to help me get an alignment. He has the same CG-5 mount. Before he got there, I got Polaris through my polar scope and had him take a look. He said that I was quite a bit off. I had aligned Polaris in the large circle and not the smaller circle. Man, I was doing it all wrong. I thought that Cassiopia and the big dipper were in the polar scope just to make it look nice. He showed me how to turn the polar scope so that the big dipper is in the same position that it is in the sky and to get Polaris inside of the really small circle. After we got that done, I was able to get an alignment but I still can't get used to the movement of the mount. That cheat sheet that I made up was of no use. Because it took so long to get the alignment, I only slewed to Saturn but it went right there. By then, it was after midnight and I had to go to work the next day so I slewed to Polaris and then put it in hibernate mode. Now, when I wake it up, hopefully it will be close to alignment.

Post Extras: Print Post   Remind Me!   Notify Moderator  
nganga
super member


Reged: 03/16/08

Re: CG-5 slewing arrows - Need Help!!!! new [Re: James Cunningham]
      #4553751 - 04/30/11 04:14 PM

Quote:

A friend came over last night to help me get an alignment. He has the same CG-5 mount. Before he got there, I got Polaris through my polar scope and had him take a look. He said that I was quite a bit off. I had aligned Polaris in the large circle and not the smaller circle. Man, I was doing it all wrong. I thought that Cassiopia and the big dipper were in the polar scope just to make it look nice. He showed me how to turn the polar scope so that the big dipper is in the same position that it is in the sky and to get Polaris inside of the really small circle. After we got that done, I was able to get an alignment but I still can't get used to the movement of the mount. That cheat sheet that I made up was of no use. Because it took so long to get the alignment, I only slewed to Saturn but it went right there. By then, it was after midnight and I had to go to work the next day so I slewed to Polaris and then put it in hibernate mode. Now, when I wake it up, hopefully it will be close to alignment.




If your CG5 is a go-to version, you may be making things more difficult than they need to be. You do need the polar alignment, but this can be as simple as placing Polaris in the center of the hole where the polarscope is inserted, if you plan visual use only.

The software mount alignment routine, in which you use initial alignment and calibration stars, allows the mount to build an accurate picture of your sky on that night. Then you can go-to any object you want, using the lists in your hand control.

As for the initial alignment stars, the software does a fair job of picking bright, easily identified stars. So, unless your sky is obscured by lots of trees or buildings, you should have no trouble findings stars for alignment and calibration. You might try using a red-dot finder, instead of the usual magnifying finderscope. Then, you see the stars without any confusion about which is which. If you have already adjusted the RDF to your eyepiece, then when you place the red dot on Betelguese, for example, then Betelgeuse will be very close to the center of you reticle eyepiece.

Clem


Post Extras: Print Post   Remind Me!   Notify Moderator  
Robert70
sage


Reged: 02/11/11

Loc: The Garden State: NJ
Re: CG-5 slewing arrows - Need Help!!!! [Re: Trev]
      #4553830 - 04/30/11 05:09 PM

On my Meade lx 90 HC the left arrow moves the scope to the left, up arrow moves the scope up etc. not sure about your HC, but you can change the direction the arrow's move the scope by going into your menu's.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
19 registered and 28 anonymous users are browsing this forum.

Moderator:  Dave M, richard7, bilgebay, iceblaze 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1619

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics