GoTo or Auto Guide?

[jackd]

Which is best for astrophotography? GoTo or Auto guide? And why?

[themos]

Autoguide capability is preferable to Goto.

Goto is only used for finding the object and, possibly, framing it in the camera. It doesn't help during the long exposure whereas autoguiding does.

[JamesF]

Agree with themos, though GOTO will be very useful if you can't actually see the target even with the scope pointing straight at it or if you don't want to spend time finding it in the first place.

James

[jackd]

So ideally, I need a set-up that does both?

[Cornelius Varley]

I think you would find it difficult to find an equatorial goto mount that doesn't have a guide port. Goto mounts are actually quite stupid.. The handset wiill send the telescope to a point in the sky where it believes the selected target to be based on the information provided by the user. After that it reverts to a simple trackng mount untill another command is sent to it. A guide port constantly sends corrective signals to the mount from the guiding software.

Peter

[JamesF]

So ideally, I need a set-up that does both?

It's not absolutely necessary, but it may well make life easier.

James

[Monty]

I'll be adding an autoguide to the CPC800 next year. Using to Goto to get close as mentioned above then autoguiding for imaging. Haven't decided on which scope to piggyback for the guide yet though.

[brantuk]

Have a look at the Altair Miniguider system - it's very light and can easily be fitted in place of the finder shoe. You can use a webcam and Phd free software to guide. I'f imaging dso's you'll also want a wedge - the new model Celestron one is perfect for the 800. HTH

[ollypenrice]

I'll be adding an autoguide to the CPC800 next year. Using to Goto to get close as mentioned above then autoguiding for imaging. Haven't decided on which scope to piggyback for the guide yet though.

I woudn't try to guide an SCT with a piggybacked guidescope. I would use an Off Axis Guider. It will be far more accurate and if there is mirror movement that will be guided out. I use guidescopes happily up to a metre of FL but on the big SCT we use an OAG. I don't know this to be the case but I'd suspect that the finder guider would have too small a FL in relation to your imaging FL in this case.

To the OP I'd say that Go To is a near essential for imaging. Many reasons. It saves time and you never have enough of that! It allows you to get back on target fast if you lose your guide star. It allows you to slew to a bright star to refocus and slew back again fast. (You can't always use a field star in the image to focus.) We are often imaging targets that have never been seen by anyone in any eyepiece. You do not want to be taking your camera on and off to frame the target. You lose critical focus and may mess up your flats situation. The list of etceteras is a long one so go for Go To and an autoguider! Trust me on this.

Olly

[JamesF]

I woudn't try to guide an SCT with a piggybacked guidescope. I would use an Off Axis Guider. It will be far more accurate and if there is mirror movement that will be guided out.

That latter point is something that had never occurred to me, so thanks you for mentioning it

James