Autoguiding?

[Galactic Wanderer]

I ve heard a bit about Autoguiding, etc. how it locks onto a star and sends info back to your mount which helps you track the stars better. But I've also heard you can Autoguiding with a simple inexpensive webcam attached to your finder scope. Is this possible? Does it send info back to your mount? Thanks

[Cornelius Varley]

The way autoguiding works depends on your equipment. The first method uses a dedicated guide cam which sends a live feed back to the guiding software on your pc which then returns corrective signals back to the camera and then on to the mount via the camera's ST4 port. With a non dedicated camera (webcam or camera without an ST4 port) the corrective commands go back to the mount through an autoguiding interface ie . The third method employs an all in one guide camera/guider which does not need a separate computer to do the guiding Skywatcher Synguider

[xtreemchaos]

great advice above from Peter, theres many ways and auto guiding set ups to look at, ive gone down the light weight route, with a modded canon lens and QHY5v cam, it works well. make sure you do plenty of reading before you make up your mind. heres a pic.  charl.

[Galactic Wanderer]

1 hour ago, Cornelius Varley said:

The way autoguiding works depends on your equipment. The first method uses a dedicated guide cam which sends a live feed back to the guiding software on your pc which then returns corrective signals back to the camera and then on to the mount via the camera's ST4 port. With a non dedicated camera (webcam or camera without an ST4 port) the corrective commands go back to the mount through an autoguiding interface ie . The third method employs an all in one guide camera/guider which does not need a separate computer to do the guiding Skywatcher Synguider

I like the sound of the second option, but this means I need to get a wire for the computer to the mount? sorry just realised it comes with the guider

[Cornelius Varley]

4 minutes ago, Galatic Wanderer said:

I like the sound of the second option, but this means I need to get a wire for the computer to the mount right?

You will need an ST4 cable (normally supplied with the autoguider interface) to connect to the mount's ST4 port.

[Beeko]

ST4 is getting a little long in the tooth now. You are best off researching pulse guiding. This is advantageous as it can identify exactly where the mount is pointing in the sky. 

[Stub Mandrel]

On 04/08/2016 at 11:40, Cornelius Varley said:

The way autoguiding works depends on your equipment. The first method uses a dedicated guide cam which sends a live feed back to the guiding software on your pc which then returns corrective signals back to the camera and then on to the mount via the camera's ST4 port. With a non dedicated camera (webcam or camera without an ST4 port) the corrective commands go back to the mount through an autoguiding interface ie . The third method employs an all in one guide camera/guider which does not need a separate computer to do the guiding Skywatcher Synguider

Thanks for this, I have been wondering why some cameras with an ST4 port need a computer - I had assumed all autoguider cameras would do the maths inside it!

[Ouroboros]

15 hours ago, Beeko said:

ST4 is getting a little long in the tooth now. You are best off researching pulse guiding. This is advantageous as it can identify exactly where the mount is pointing in the sky. 

Why is that an advantage?  I use the ST4 method via PHD2 running on my laptop mainly because that seems to work for me. I was concerned that pulsed guiding might add a level of complexity that I don't need when setting up and tearing down every time.  But maybe I'm wrong to assume that. After all I'm now using my laptop to control the mount via EQMOD and to gather images via BackYard EOS, and guide via ST4. 

Does pulse guiding give inherently better guiding?  Has anyone ever done a comparative study of the three methods?  i always imagine that stand-alone guiding is the least accurate. But I might be wrong and it always looks like the simplest method, especially for the beginner or those who just want to get out there imaging as quickly and conveniently as possible.   

[Beeko]

http://www.cloudynights.com/topic/473363-st4-vs-pulse-guiding-question/

this is the first of many links you'll find if you just google 'why pulse guiding is better than st4'  It doesn't make much different but if you are starting out with guiding, might as well use the slightly better method  

 

[Stub Mandrel]

So what is the difference between pulse guiding and ST4 other than ST4 going to the control box via the handset?

 

 

[Ouroboros]

In ST4 guiding you connect the guide camera to a USB socket in your PC.  You also connect the camera to the mount via the ST4 cable. Guiding software like PHD2 for example sends correction signals back to the camera which relays the signals over the ST4 cable to the mount. ST4 guiding is appropriate when you are using the handset to control the mount and you are not controlling the mount directly from the computer. 

If you move up to controlling the mount directly from a PC using EQMOD/ASCOM etc all sorts of features become available including controlling the mount pointing with planetarium software like Cartes du Ciel, polar alignment, making mount adjustments via a gamepad, and lots of other stuff including guiding. In pulse guiding the camera is still connected to the PC but no ST4 cable is necessary because guide signals are sent directly to the mount via the cable connecting the PC to the mount. I hope that description is right as I've never actually guided this way! 

 

[Beeko]

Yes, perfect explanation above. You only need use one cable, you can also take advantages of the ascom drivers hence if you use stellarium, etc the mount has a Dec/RA idea of where it is. For some mounts, using the ascom is better than relying on the mount to do the work. Having said that, if st4 is working fine for you then.....

[Stub Mandrel]

Thanks, I plan to add guiding to my GOTO box* as well as a USB interface for mount commands. I need to choose what interface to use, of course and ASCOM seems like major uphill battle to access the documentation without it taking over my entire HDD... I will probably take a simpler approach.

I'm not sure that there would or could be any difference between ST4 and pulse guiding in the way I have started to implement it - ST4 would just be the route by which the controller is told to make extra moves. ST4 seems so much easier to implement though as I am still struggling to understand exactly how PHD sends guiding commands. I need to do more reading.

 

*which is working well, except I appear to have errors in the location data for couple of stars which shows up as very peculiar slews if I align on a dodgy one...