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Astrophotography and Sketching >> Beginning and Intermediate Imaging

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jrcrillyAdministrator
Refractor wienie no more
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Reged: 04/30/03

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Re: New Orion "thin" OAG new [Re: Raginar]
      #6106726 - 09/28/13 11:09 PM

Quote:

K, so I tried it tonight and got stars. But... It's 2 inches from the center of it to the tip of my lodestar... so that means I need my camera to be at least that far away too right?I need another spacer to make it happen.




It is the other way around. You focus the telescope with the main camera. THEN you put the guide camera wherever it needs to be to be in focus at the same time.


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Raginar
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Reged: 10/19/10

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Re: New Orion "thin" OAG new [Re: Raginar]
      #6106750 - 09/28/13 11:21 PM

And is it truly from the center of the OAG to the guide camera has to be equal to the center of the OAG to the main camera?

Or is it based on where your prism is?


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Wmacky
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Reged: 11/24/07

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Re: New Orion "thin" OAG new [Re: Raginar]
      #6106988 - 09/29/13 06:30 AM

No, it's from the prism, and yeah, focus the main camera first, then match the guider.

Ball end? I thought you were going for a machined driver? Never seen a machined ball end wrench??

Edited by Wmacky (09/29/13 06:32 AM)


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Raginar
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Re: New Orion "thin" OAG new [Re: Wmacky]
      #6107239 - 09/29/13 11:09 AM

I went looking for one and couldn't find it. I ordered one online .

Ok so it's prism stalk length needs to match the distance to the ccd. I probably was pretty close. But the problem is you have no adjustment. As soon as I tried to move the top part it wobbled... With almost no spacers on it. I bought a tap set so I can throw a small 4-40 screw in it. I'll let you know.


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Dan Watt
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Reged: 10/13/09

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Re: New Orion "thin" OAG new [Re: Raginar]
      #6112234 - 10/01/13 11:30 PM

I added a few extra set screws to hold mine in better, works like a charm. No wobble at all anymore. Hopefully Orion will redesign the next batch to include this modification because it looks like it work perfectly now.



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Raginar
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Re: New Orion "thin" OAG new [Re: Dan Watt]
      #6112892 - 10/02/13 10:59 AM

Cool. I bought the bits but didn't get to it. Thanks for posting that.

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BaltimoreCaesar
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Reged: 07/08/13

Re: New Orion "thin" OAG new [Re: Raginar]
      #6113039 - 10/02/13 12:25 PM

This may be a newb question, but why would you want a guider blocking the light path of your primary which will reduce contrast, when you can just stick one on a the back of your finder scope (or a second finder scope)? Am I missing something?

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Wmacky
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Reged: 11/24/07

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Re: New Orion "thin" OAG new [Re: BaltimoreCaesar]
      #6113452 - 10/02/13 04:07 PM

Because:

The small prism is adjusted to be out of the light path reaching the imaging chip.

Also.

Flexure in separate guide scope systems can lead to non round stars when imaging at long focal lengths, such as using a SCT at its native focal length.

Edited by Wmacky (10/02/13 04:14 PM)


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Phillip Easton
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Reged: 12/24/10

Loc: DFW
Re: New Orion "thin" OAG new [Re: Dan Watt]
      #6114703 - 10/03/13 08:38 AM

Dan,

I agree those are what are needed to make this an excellent TOAG. Hope Orion listens.

Did you add lock screws on the part that has the thumb screws for side to side movement? I think it needs them there too.

I need to send them a video of the wobble even when fully seated. Didn't get a chance to do it before heading out to Okie-Tex.

Cheers!

Edited by Phillip Easton (10/03/13 08:40 AM)


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Dan Watt
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Re: New Orion "thin" OAG new [Re: Phillip Easton]
      #6116481 - 10/04/13 01:48 AM

I have no added anything, it felt fine on the bench but I have yet to try this out in the field. I'm going out to the desert this weekend for imaging so I will have to report back with my findings.

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Wmacky
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Reged: 11/24/07

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Re: New Orion "thin" OAG new [Re: Dan Watt]
      #6128596 - 10/10/13 09:16 AM

How's the experimenting with this thing going?

I was hoping to use the Edge T-adapter with this OAG, but I'm afraid that's not going to happen. With just the t-adapter and OAG, the back focus 3mm over. Thats not too bad, but that leaves no back focus space for a LP filter, and no place to thread one in for that matter. The worst part is that I just tried to thread the T- adapter into the OAG, and it appear to collide with the Prism shaft before it fully seats. It almost damaged the prism! Looks like I'll have to piece together various adapters / extenders. Bummer!

One last issue is the AT2FF flatner I'm soon to purchase. Those threads look pretty long, and it may also make contact with the prism? Anyone have both these items?





Edited by Wmacky (10/10/13 09:40 AM)


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josh smith
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Reged: 10/13/13

Loc: Pittsburgh, Pennsylvania
Re: New Orion "thin" OAG new [Re: Wmacky]
      #6173412 - 11/03/13 10:15 AM

I wanted to bump this thread. I am interested in trying this oag since the reviews make it sound more sturdy than the German version and smaller than the Lacartes. Has anyone found success using this with a ff and dslr? I use clip filters so using them eliminates any extra spacing or adapter requirements. Looking forward to any additional feedback. Thanks.

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Raginar
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Re: New Orion "thin" OAG [Re: josh smith]
      #6173663 - 11/03/13 12:27 PM

It works with a field flattener just fine. I have a at2ff. It really just needs an additional set screw on the adjustable part.

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petemumbower
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Reged: 07/12/09

Loc: West Michigan
Re: New Orion "thin" OAG [Re: Raginar]
      #6173986 - 11/03/13 03:49 PM Attachment (14 downloads)

I added an additional set screw at 90deg as shown in the pic below. There still is a little bit of play on that axis. But I am a bit hesitant adding one on the other side. It is fairly thin-walled and I am concerned about stripping what little thread there would be.

But thinking about it and playing with it to see were the play is, I can see the stalk itself is moving. There is just the one set screw holding the stalk in place. Maybe a 90deg set screw there would take care of the remaining slop?

But I agree, Orion should make a version 2 of this to address this silly problem.


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Raginar
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Re: New Orion "thin" OAG [Re: petemumbower]
      #6174002 - 11/03/13 04:02 PM

Pete,

Where else are you seeing it flex? you mean physically the prism part?


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petemumbower
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Reged: 07/12/09

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Re: New Orion "thin" OAG [Re: Raginar]
      #6174013 - 11/03/13 04:09 PM

Chris,

Yeah, there is just the one set screw on the TOAG body that holds the prism part in place. It comes in from the side, since the prism stalk is a bit smaller that the opening in the TOAG, there is play. I can wiggle it with my fingers. Not sure how much would actually move while imaging, especially once the one set screw is tightened. But it does move, so I am serious thinking of adding a set screw 90deg to the existing one just in case.


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josh smith
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Reged: 10/13/13

Loc: Pittsburgh, Pennsylvania
Re: New Orion "thin" OAG [Re: petemumbower]
      #6174023 - 11/03/13 04:15 PM

Quote:

Chris,

Yeah, there is just the one set screw on the TOAG body that holds the prism part in place. It comes in from the side, since the prism stalk is a bit smaller that the opening in the TOAG, there is play. I can wiggle it with my fingers. Not sure how much would actually move while imaging, especially once the one set screw is tightened. But it does move, so I am serious thinking of adding a set screw 90deg to the existing one just in case.




Two questions...

Is the stalk made out of aluminum and use a steel set screw? Does that create divots in the aluminum that make it hard to adjust focus without set screw falling into previous divots?

Do you guys just user spacers for the guide cam and thread it or does anyone use a t thread to insert tube or t thread to helical focuser? Seems like a threaded connection would make orientation adjustments difficult.


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petemumbower
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Reged: 07/12/09

Loc: West Michigan
Re: New Orion "thin" OAG [Re: josh smith]
      #6174058 - 11/03/13 04:30 PM Attachment (15 downloads)

Josh,

Yes, the stalk appears to be made out of aluminum and the set screws are steel. At this point, I do not see any divots that would cause issues down the road. For focus, I got a 1.25" eyepiece adapter from Agena. See below pic. I use a QHY5L-II guider and basically slide it up and down until I got focus (after I focused the DSLR first). Then I used the suppied QHY focus collar. That focus should not change unless I change my setup.

Also, since I do not need to move the prism stalk up and down for focus, I really am not too worried about divots.


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josh smith
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Reged: 10/13/13

Loc: Pittsburgh, Pennsylvania
Re: New Orion "thin" OAG [Re: petemumbower]
      #6174075 - 11/03/13 04:44 PM

Thanks Pete.... I figured that would be the better solution, but didn't know if the stalk could handle it or not. Since I am using clip filters, it is likely that I will have to adjust focus on the guide cam (ST-i) regularly by ver small amounts. Not even sure if the filters will change backfocus enough to require guide cam adjustments, but nice to be prepared. I feel pretty convinced now that this is the way to go.

My 2 cents on the stalk issue would be to just permanently bolt it into place and use an attached 1.25" tube for focus. Seems like sensitive guide cams should be able to pick up bright enough stars anywhere if imaging at less 800-900mm focal length.


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josh smith
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Reged: 10/13/13

Loc: Pittsburgh, Pennsylvania
Re: New Orion "thin" OAG [Re: josh smith]
      #6174086 - 11/03/13 04:51 PM

One other thing... Would any of you know the distance from the center of the pickoff prism to the top of the stalk to determine spacing requirements? Thanks in advance for any answers.

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