extended exposures with sc c11

david3
04 Apr, 2017 20:32
Hallo there .
Is there someone who could help me?
I have an sc c11  with focal reducer 6,3 on AZEQ6 , telescope guide sw80ed and guide camera synguider 2 stand alone.
I can't make extended exposures,after about 40 seconds my pictures are moved.
I don't have this problem with newton 200/1000 and sw80 ed.
Could you give me some advice?
Thank you all…. bye bye guys.
KuriousGeorge
05 Apr, 2017 04:31
You guide on a star and your image has blurry stars? That sounds like polar alignment is off or your guiding is not working.
Edited 05 Apr, 2017 04:32
david3
05 Apr, 2017 11:16
Thank you george 4 your answer but my focus is ok I use bathinow mask.
I think it's impossible to guide my c11 with my set up or not?
I'll hope to find someone thaT use c11 with my set up.
I think my polar allignement is ok otherwise my pictures will be move with newton and sw80ed too,while with them i can make long exposures about 6 or 8 minutes.
Yes maybe I don't use correctly my guide…….do you know this type of guide?(synguider2 stand alone)
Bye
astroian
05 Apr, 2017 13:45
Hello,

It maybe that you're experiencing mirror shift. As the scope moves, because the mirror is just resting on the central baffle it can shift around as the scope tracks across the sky. Of course this won't be seen by you guide scope. You will need to use either an OAG or an ONAG. I use the latter, but with the Edge HD which also has mirror locks to keep the mirror in place.

Cheers,
Ian
KuriousGeorge
05 Apr, 2017 14:49
Better to have someone answer with your setup. But as Ian says, mirror shift could be a problem. You may also need to slightly unbalance the c11 in ra and dec to keep backlash under control by keeping a load on the worm gear teeth.
Edited 05 Apr, 2017 14:54
bobzeq25
05 Apr, 2017 22:19
You're running up against stuff that is neither intuitive nor obvious.

Tracking difficulty increases very fast as the focal length increases.  It is not linear, ie twice the focal length is more than
twice the difficulty.

As others have stated the mirror moves.  Most people imaging with a C11 use an off axis guider to combat this.  And an
expensive guide camera, which the OAG wants.

Weight hurts, too.

The bottom line is that imaging with an ED80 is relatively easy.  A great starter scope.  The Newtonian is mildly difficult.
A scope for someone with experience.  The C11 is very hard.  Really, an expert's scope, and one that requires special
equipment.  A focal length reducer is used by most C11 imagers.

Not intuitive, not obvious.  But true.

Best advice.  A couple of years  (not kidding) experience with the other scopes would be good before tackling the C11.  It's better used as a visual scope or a planetary imaging scope.  Not DSOs.
Edited 05 Apr, 2017 22:23
david3
06 Apr, 2017 00:57
Thank you very much guys for your advices I understood many things.
I'll follow the advices and I hope to manage to show you one pictures not moved with my c11 one day.
Bye bye
Testgear
11 Apr, 2017 14:12
Dont blame me if this does not work for you!! lol
Most of this can be done during the day. The Guiding will have to wait until night!Make a note of all your PHD2 settings. All the info in the brain too. Put that info somewhere safe smile

I used to have a similar setup. The C11 on a NEQ6 Pro mount with a 80mm guide scope is adequate.
I found I had similar problem to this. Would start guiding and after a few moments, PHD2 would go walkabout.
Now, as I said..//Dont blame me if this does not work for you!! lol

My remedy was -
Before powering on, check the balance of the equipment! One at a time and make sure one is tight before releasing the other. Release the clutches and see if the OTA and the weights balance?
Move the OTA and weight so they are horizontal, close the DEC clutch and release the ALT, does that OTA with all its accessories attached, including DEW shield if used. Balance OK? If so, Great smile
Power on, Start again with PHD2. Click on the Brain. Select RESET CONFIGURATION. Do the darks for the guide camera. Check all the settings are good. Slew to a star around 30 degrees above the horizon and start guiding. It will do its routine, north, east etc. When it starts guiding Open TOOLS and select Guiding assistant. Run that for at least 2 minutes. Apply the results, slew to your prefered area of sky and try imaging.

Good luck smile

As I said, this works for me. Maybe there are better ways, I don't know. I am, like many of us, self taught smile
Use at your own risk smile
CarstenEckhardt
10 May, 2018 17:36
Hi David,
as mentioned above, there could be many possible problems (balance, polar alignment etc.) but in your situation with this specific equipment, I would recommend to

1. Since you are using a stand alone guider and not Phd2, read the manual, and search the internet on how to improve guiding with the Synscan. Like said above, with 2800mm of focal length, the errors you had before get multiplied!

2. Without a mirror lock  (like in the HD models) it is always recommended to use an off axis guider. Implementing one into your system should be the easiest and simplest solution (and cheapest). Don't give up yet, because it kind of is like rocket science ^^

I'm using Phd2 and despite the name (Push here Dummy) it is easy to use, but very difficult to perfect and at almost 3 meters of focal length, you have to optimize a lot.  Don't give up yet!!!

I added a quote: https://www.cloudynights.com/topic/592296-off-axis-guider-question/#entry8112912

bpaczkowski
"I have an 11" EdgeHD and started out with a guidescope.  I spent about 6 month struggling with guiding and flexure.  As soon as I went to an OAG everything was easy.  Start with the OAG, you won't regret it.  Make sure you get a sensitive guide camera.  I use the Celestron OAG with the QHY-IIM and I never have a problem finding guide stars."
Edited 10 May, 2018 17:47
trombone76
10 Jul, 2018 05:30
I had a C11 non edge and the only way I was able to manage 1 to 2 minute subs unguided was the use of a Losmandy G11 Gemini II with an
RA Ovision worm. Even with that setup at f10 2650mm it was a real challenge to achieve 1 minute unguided subs. The real fun began when I
had the C11 converted for hyperstar use from the kind folks at Starizona. Once that was done I was at 520mm F2 and then was able to do 5 minute unguided easily and really then only needed 180 second subs to get good detail.
 
Register or login to create to post a reply.