Auto guiding a Orion 16g, How to please, Advise needed.

[Bignev]

Hi would anyone be able to help me out here a bit as i have a Orion 16g telescope and as you might have noticed it don't come with a auto guiding socket  on the base so as things stand it will only be able to track star wise for the usual seconds before i get star trails and i cant believe that a scope of this quality would not have been already fitted with one, a real bad decision if you ask me . I have found a article on the net for making a DIY system for your scope but i am very new and i need to know if this sounds like a viable project to undertake as i want to really get into the astro photography  side of things and i believe this scope would be just fantastic for the purpose, and of corse  its a job i would be willing to undertake if i get the right feedback from someone in the field.

The article is on this site,  Night Sky in Focus, and the page is,  DIY Autoguider: Home-Built Autoguider Project

I have gone through the article hundreds of times and it all sounds fairly straight forward and i can't see any problems but i would like to have someone's advice who has some brains of these things before i commit myself, i have virtually already made my mind up to go ahead but it wouldn't hurt to try and get some proper advise.

I have found a very nice camera\guider for sale today the Orion Star Shoot AutoGuider Pro Mono Astrophotography Camera but operating systems are updated to win 7 instead of the old win XP.

I have had my scope since April last year and hardly been able to use it yet so i am just trying to get my system up and running as good as i can and at least it will be ready and waiting for when i am going to need it, when dark skys return that is.

Any help would be really grateful, Many thanks for any help received.

[Daniel-K]

are you trying to image with a 16" push to dob?

[Bignev]

yes its the new 16g thats got the goto system on it, i have my camera setup complete i just want to be able to turn it into a guiding scope so i can take long deep exposures  if that is possible

[Steve Ward]

It may be Go-To but it's still an Alt-Az mount that does not 'track' in the way that an Equatorial mount does , it goes a little bit right then a little bit up rather than following accurately the rotation of the Earth.

This unfortunately means that it will never perform for long-exposure photography .... 

[Daniel-K]

you will struggle with it being an ALT AZ mount.even if you got it guided it wouldn't be as accurate as a GEM mount and you'd end up with field rotation. GEM mounts are what imagers normally use  for long exposures due to there accurate gears and motors. you may be able to get a few images but you really are limited to the amount of exposure time you can do

[ronin]

It is an Alt/Az mount, even if you track you will get field rotation.

The mount is not suited to long exposure DSO imaging, guided or unguided.

Actually guiding will make you try longer exposures that result in more field rotation.

[Bignev]

Thanks loads that is just what i needed to hear at least i can forget the idea there now, would the maximum time be around a minute as i say i am very new to this side,cheers.

[Cornelius Varley]

Alt-azimuth mounts, even the ones with goto aren't suitable for long exposure DSO. The way an alt-azimuth mount tracks means that after a short period the stars will have rotate within the field of view. This is why auto guider ports are not fitted to alt-az dobsonian mounts.

[Cornelius Varley]

Thanks loads that is just what i needed to hear at least i can forget the idea there now, would the maximum time be around a minute as i say i am very new to this side,cheers.

It depends on the focal length of the telescope, but 30 seconds would by a more practical maximum.

[Bignev]

Many thanks again guys i am  glad i didn't just go ahead with it there now, Many thanks again, i will just enjoy my scope as it is and when i can, Cheers

[Christopher Davenport]

Don't give up that easy!

http://www.telescope.com/Telescopes/Dobsonian-Telescopes/Truss-Tube-Dobsonians/Orion-SkyQuest-XX16g-GoTo-Truss-Tube-Dobsonian-Telescope/pc/1/c/12/sc/29/p/102659.uts#

Based on this link your telescope is a 406mm and the focal length is 1800mm, if you can get this to track a planet then you can do some fantastic planetary / lunar imaging.

This would mean using the live view on your DSLR, or purchasing a dedicated planetary imaging camera. (ie a QHY5L II or similiar)

Another option, if you want to take some deep space stuff, is get a coma corrector reducer and push the focal length and f ratio down.

I.e a 0.9x reducer corrector would make your telescope a f4 scope at 1600mm focal. 

At this speed, you could take couple of hundred 30 to 45 second subs and get pretty good results. (not deep field, but enough to impress your mates.)

My moto is if not, why not. You may find that imaging is not your thing and then at least you gave it a bash.

But if you really enjoy it, you may decide to keep the dob for visual and dive into imaging.

I suggest you get a copy of "Make every photon count" as this will help you get started in imaging.

[Bignev]

Thanks christopher i will definatly be looking into that, Cheers

[dph1nm]

It all depends how well the alt-az mount tracks.  Field rotation is not dependent on focal length, and generally limits imaging to around 1min (depends where you are in the sky).  However, at long focal length the mount may not track well enough even for that time - try it and see I guess.  I would recommend binning up the data to make the pixels bigger - makes the effects of trailing appear less!

NigelM

[Zakalwe]

It's not the easiest way of doing it, but it can be done!

http://www.iceinspace.com.au/63-201-0-0-1-0.html

http://www.dansdobimaging.com/index.html

He's using a fair old light-bucket, to be fair.