Guiding using a non-goto CG-5 mount

[RobertI]

Hi all,

I'd appreciate some advice. I recently started imaging and I have a portable setup comprising a Williams Optics ZS66 with flattener (total focal length = 310mm) plus Canon 1100D on a Non-Goto CG5 mount. I have had good results imaging at 60 second exposures but that’s about the limit before I get trailing. I suspect I could get 90 – 120 secs with really good polar alignment (can anyone confirm?). However I am keen to try guiding to get longer exposures and I have modded the handset to add the Shoestring Astronomy GPUSB which effectively adds an ST4 style port - this actually seems to work and the scope now reacts to commands from PHD using an Altair Astro Mini-Guider and Lodestar Guidecam.

However my initial attempt at guiding wasn’t brilliant and I get all kinds of trailing at more than a minute. I am pretty sure that flex is not an issue the setup is very solid and lightweight. I have adjusted the motors to remove as much ‘play’ as possible. With the lousy weather I haven’t had a lot of time to ‘tweak’ any of PHD settings but I am starting to think that the Non-Goto CG5 (with its stepper motors) is just not up to the job and will not be able to react smoothly to guide commands.

Has anyone out there successfully guided a non-goto CG5 for imaging at 300mm? If so what’s the maximum exposure I could reasonably expect? Or am I wasting my time and should I stick to un-guided until I can afford a better portable mount? Or am I trying to run before I can walk?!

Any advice greatly appreciated.

Rob

[RobertI]

Anyone?

In summary, is my non-Goto CG5 mount capable of providing reasonable length guided exposures at 310mm focal length?

[glappkaeft]

In summary, is my non-Goto CG5 mount capable of providing reasonable length guided exposures at 310mm focal length?

Definitely and the shorter focal length just makes it easier. With a good polar alignment you should be good for at least 3 minutes (I have done 3 minutes with 1000 mm).

[RobertI]

Definitely and the shorter focal length just makes it easier. With a good polar alignment you should be good for at least 3 minutes (I have done 3 minutes with 1000 mm).

That's great, thanks for the response. I'd be really happy with 3 minutes!