Changing from Oag to Guidescope?

[Jgw]

Hi folks, could do with your experiance & opinion here! I have been useing my Oag some time now, and I can,t seem to find a suitable

guide star, since the Fov is very limited, plus the fact my patience is now running low. By the time I set things up, its early in the morning! You probably know what I mean..

Thinking of buying a Guidscope to make life easier, ( I hope) if so,what would be the best buy.....?

Be glad for some feedback..

Cu John

[r3i]

I guess you're at the end of your tether but I would try to persevere a bit longer to get the OAG working, I recently switched from piggy-back to OAG and wouldn't go back.

Just a few questions/suggestions about your OAG setup:

• What main camera and guide camera are you using?
  
• Have you done daylight testing on a terrestrial target to get the main camera and guide camera in focus at the same time?
  
• If you've done the daylight check, then fine-tune the focusing by pointing the main camera at a very bright star, getting that in focus (use a Bahtinov Mask) then move the mount so the star migrates to the guide camera FOV - keep the Bahtinov Mask on whilst you're doing this as the lengthy diffraction rays make it easier monitor the star's location as it moves from one FOV to the other. I do this everytime, it only takes a couple of minutes and is worth the effort.
  
• Have you tried the radial adjustment on your Celestron OAG? Occasionally I've had to rotate my guide camera a little bit to locate a bright enough guide star.
  

If you've made your mind up on switching to a guidescope then I've often seen the SkyWatcher ST80 being recommended as a good one to go for. Another option that folks go for, especially to keep the weight down, is a finder-guider arrangement.

[Jgw]

Hi, I know Patience is a virtue!

I ,am quiding with the spc900 webcam, and using the Canon 350D for imaging...

To be honest, I have not tryed that focusing in the daytime, by the time I arrive home from work its dark. Anyway will try at the weekend and see if things turn out better..

When setting up , I use the bahtinov Mask , and get the Camera in Focus, the trouble is,finding a star in this small Fov. That is a good idea with the diffraction rays, never thought about that!

The Radial Adjustment on the OAG, I have moved a few Times, but finding a bright star near enough to the object of interrest, up till now no joy...

Anyway manythanks for your reply, will try things out at the weekend, weather permitting..

Regards, John

[Psychobilly]

I think OAG's work best with a sensitive guidecam.. that way you will have a lot more chance of finding guidestars... your choice will be a lot more limited with a webcam...

Peter...

[Merlin66]

I agree with Peter, upgrade the guide camera first to one which allows a longer exposure...QHY5 or similar is a good starting point.

[r3i]

Agree also!

I wondered if you were using the webcam as your guide camera, which I why I asked the question. The QHY5 as suggested by Merlin looks to be a popular choice. An alternative to consider is a Meade DSI - they are often available secondhand at a decent price. I have the DSI I colour version which works well but I understand that the mono DSI I or the mono DSI II make particularly good guide cameras due to their increased sensitivity.

The daytime test is well worth doing - you can take your time, and will get your setup pretty close. Then when you come to testing at night with a bright star, you shouldn't be far off.

[ollypenrice]

More agreement from me too! I'd also second the ST80 as the ideal piggybacker but I have never fancied webcam guiding since better guide cams are so much cheaper than they were.

Olly

[Jgw]

HI Folks

Many thanks for your comments, I will look around to see whats on the market!

Will keep you informed with the results!

Cu John