PHD guiding

[Moonshed]

Could someone please explain to me what PHD guiding is and GP-CAM. I have never done any guiding but of course that means I am restricting myself. What equipment is involved and how is the guiding achieved? I take it that it is not automatic guiding? At the moment I am restricted to around 150 seconds unguided. The thing is though I can't really add much more weight to my mount so weight is an important factor. I appreciate this may seem a dumb thing to ask but any help would be appreciated.

Thanks, , Keith

[Davey-T]

The best thing to do is find some online explanations from the PHD2 site and You Tube, the GP Cam is a small mono camera that can be used in conjunction with a small telescope and PHD to track a star and guide your mount to stay centred on it. 

There are a few different guide cameras available some of which can be used for capturing images as well.

Dave 

[newbie alert]

What equipment are you using at the moment?  PhD helps massively to lock onto that guidestars and far exceed to mounts capability of highly accurate tracking..you can use any planetary cam don't have to be a gp cam..lots use zwo 120..right up the the lodestar and equivalent..

[geordie85]

PhD is a program that sends corrections to your mount if a selected star moves from where it originally was. Once calibrated it is automatic. 

The GP-CAM is a small camera (amongst alot of others, zwo asi120, qhy5L-ll ect) that is connected to a small scope (alot of people, including myself, use a 9x50 finder scope) that PhD basically looks through to see stars to keep them where they should be.

[kens]

PHD does indeed enable automatic guiding (or auto-guiding). Back in the olden days we used to guide manually using a separate telescope and crosshair eyepiece focussed on a guide star centred on the cross hairs. When the guide star moved from the crosshairs you would make small corrections on the hand controller to recentre it. Autoguiding replaces the eyepiece and manual corrections with a camera and software connected electronically  to the mount. PHD is the software in this case and it sends commands to the mount to make the necessary corrections that keep the guide star centred.

Most people use a second telescope as a guide scope but if weight is a problem you can use an off axis guider  (OAG) which attaches to your imaging scope and sends a small part of the field of view (which is not seen by the imaging camera anyway) to the guide camera. So the only additional weight is the OAG which is quite light) and the  guide camera. However they are a bit fiddly to set up and finding a suitable star to guide on is more difficult.

[Moonshed]

Thank you for all your replies, most appreciated. I now understand what it is all about. Certainly makes longer exposures possible but at the cost of another level of technical complications.

thanks again.