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Old 24-03-2011, 10:02 AM
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allan gould
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Happy guiding eventually with Orion OAG

I recently purchased an Orion off axis guider to use with my 10" SCT and QHY8 camera. I must admit that I was not impressed with the quality of the OAG as the parts are not machined tightly enough and there is slop between all major parts despite the use of two screws to tighten every thing up. But after taking each aspect one at a time I finally managed to shim each moving part so that it was rigid enough to use for guiding.
As a test object I used Eta Carina as there would be enough background stars for the OAG to see and I could get a lock on. I used PhDguiding with 2 second integrations with my DSI II camera as a guide camera through the OAG. Shifting the prism with the small screw is possible but it winds up shifting the plane of focus as well so that stars outside of that plane are seagulls.
Anyway I had done 5 and 10 minute integrations with the OAG and QHY8 so I wondered how far I could push it, so I tried 20 and 30 minute shots with the qhy8. Ive attached an unprocessed shot of the whole field of the 30 minute shot and a 400x enlargement of the region around Eta Carina. Stars are really sharp and symetrical and I was very happy with the low noise in the shot as well as the tracking. However it looks like the OAG causes some vignetting, but thats easily removed with a flat field.
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  #2  
Old 24-03-2011, 10:42 AM
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Visionoz (Bill)
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Allan

Which of the Orion OAG model did you use?

Cheers
Bill
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Old 24-03-2011, 12:46 PM
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telecasterguru (Frank)
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Allan,

I'm very impressed. I have my Deluxe OAG fitted to the QHY9/CFW and ready to try this weekend. I can't wait for the SPSP to try under really dark skies.

Frank
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Old 24-03-2011, 04:56 PM
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Quote:
Originally Posted by Visionoz View Post
Allan

Which of the Orion OAG model did you use?

Cheers
Bill
It's the Orion deluxe off axis guider, Bill. Bit disappointed in the quality but with a bit of work you can make it solid.
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Old 24-03-2011, 04:59 PM
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Originally Posted by telecasterguru View Post
Allan,

I'm very impressed. I have my Deluxe OAG fitted to the QHY9/CFW and ready to try this weekend. I can't wait for the SPSP to try under really dark skies.

Frank
I suggest that you carefully inspect it for flexure at all points especially where the prism holder meets the body of the guider. Although there are two screws to hold it firmly in place there can be enough room for it to flex even when the screws are really tightened. A small piece of paper takes up the gap and makes it solid. Check it befor eyou go and make sure you focus the scope and guider in daylight on the same object as it will be an extremely frustrating exercise in the dark. Don't say I didn't warn you.
Allan.
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Old 24-03-2011, 05:20 PM
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The sneaky little grub screw holding the alignment of the prism is a real PITA!
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Old 24-03-2011, 06:31 PM
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The sneaky little grub screw holding the alignment of the prism is a real PITA!
Would have to agree, but I snugged it down to start off with and have not heard from it since.
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Old 24-03-2011, 07:01 PM
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Merlin66 (Ken)
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I was trying to help a guy over here in the UK set up the Orion OAG....
he was having endless problems etc etc etc so I asked him to send it to me to "set-up" for him...
The problem was the pick off prism had rotated off axis due to that screw!
I fixed it and set the necesary spacers etc but it was too late; the guy decided it was "all to hard" and sold the OAG and went to an ST80/QHY5 arrangement.
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Old 24-03-2011, 07:20 PM
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Well worth the effort, that is sensational tracking.

Greg.
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Old 25-03-2011, 08:38 AM
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Im probably going to go this way - I like the idea of an OAG.

Are there any other models beside the Orion that you would recommend?
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Old 25-03-2011, 09:12 AM
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Im probably going to go this way - I like the idea of an OAG.

Are there any other models beside the Orion that you would recommend?
Thanks Greg and Tim, I was happy with the tracking of the mount but not happy with the Orion OAG. I did some tests last night at a focal length of 2500 mm and the OAG. It was really difficult to get stars to focus at that focal length and the best I could get was an unfocused blob. Anyway I went with that and did 5, 10, 20 and 40 min guiding with the naive FL of my 10" SCT.
I was able to get perfectly round stars out to 40 mins so I was happy with that. I'll post some pictures at a later date. The Orion OAG is a knock off of the Celestron OAG which is better built in my opinion but if I were to buy one now it would be on the condition that you get it to focus.
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Old 25-03-2011, 11:23 AM
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I thought the Lumicon Newt OAG was very good, then the Celestron Radial.....the Meade came last....
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Old 25-03-2011, 12:40 PM
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Merlin
Im looking at the Lumicon Newtonian OAG at the moment as a replacement for the Orion OAG. Although thtter works fine on stars at 1800mm focal length it starts to fall away at 2500 FL. Although I must admit I was able to do a 40 min sub at 2500mm FL and still get round stars (see http://www.iceinspace.com.au/forum/s...ad.php?t=73559).
But thanks for the advice.
Allan
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Old 28-03-2011, 09:00 AM
garymck (Gary)
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and I'm waiting for clear skies to test my Baader Rowe coma corrector and Baader off axis guider combo........As usual the weather forecast for tonight is clear and I have to work........

cheers
Gary
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Old 28-03-2011, 10:52 PM
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Best of luck Gary, I hope all goes well and the skies clear up
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Old 28-03-2011, 11:44 PM
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Hi Allan,

Have you been doing OAG with your QSI583wsg? I pretty happy with the OAG using mine - 10min shots easily when I was playing over the weekend. Might have to try some long Ha shots!

DT
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Old 30-03-2011, 09:37 PM
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Yes since I was using the OAG incorporated in my QSI583wsg I thought I would purchase an OAG to use with my QHY8. Hope you have good success with your wsg.
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Old 30-03-2011, 11:31 PM
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Thanks Allan.

Maybe OAG will be making a resurgence now that guide cameras are becoming more sensitive.

DT
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