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Astrophotography and Sketching >> Beginning and Intermediate Imaging

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Ranger Tim
scholastic sledgehammer
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Reged: 03/25/08

Loc: SE Idaho, USA
Re: New Orion "thin" OAG new [Re: Thirteen]
      #6085087 - 09/17/13 12:01 AM

Wish there was a review of this OAG along with the other affordable ones, i.e. Celestron, Teleskop Service, etc. I know this accessory is in my very near future. Hope there are enough stars for guiding!

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Phillip Easton
sage


Reged: 12/24/10

Loc: DFW
Re: New Orion "thin" OAG new [Re: Ranger Tim]
      #6085542 - 09/17/13 09:18 AM Attachment (40 downloads)

So getting ready for Okie-Tex I ordered Orion's new Thin Off-Axis Guider (TOAG). I had the scope set up from testing a new RA gear for my mount so I was excited to try this out and run it through it's paces before making the trek to the panhandle later this month. So Monday morning I got up and assembled the TOAG with my Canon 60D and StarShoot Auoguider. Got them both to focus at the same time on a distant house so I am good to go for star trials. Guess what, it has been cloudy ever since and predicted to be the rest of the week!! Arrggh!

The instructions recommend checking initial focus during the daytime on a distant object. I must agree this is prudent suggestion as it makes it much easier to changes things, make adjustments, etc. However, there are a couple of errors or inaccuracies in the instructions. First there is a reference to Figure 10 and there is no Figure 10. I also think the instructions would be better with a diagram showing which Allen screws to loosen to adjust the prism and the focus of the autoguider. Second it is implied that distance from the main camera to the center of the TOAG and the distance from the camera to the center of the TOAG should be the same. However, if you work on this assumption you will not be able to obtain focus on the autoguider.

In order to obtain focus the distance between the main camera sensor to the center of the TOAG and the distance between the autoguider sensor and the center of the prism need to be about the same. For my Canon 60D DSLR this distance is around 49mm. To get the distance between the autoguider sensor and the prism to be around 49mm a spacer is required. I used the 5mm spacer from the Orion T-Thread Spacer Ring Kit, (which thankfully I already had). I then loosened the screws close to the autoguider platform to refine the focus by slightly pulling out (about 1mm) the autoguider, (with the main camera in focus). Then moved the prism down so the assembly rests on the TOAG body to lessen the chance of flexure of the prism stalk.

I also removed the step down ring and I am using a modified Hotech Self-Centering Camera T-Adapter for the nose piece. It screws right into the M48 threads.

Also the instructions don't mention it but you can screw on the SSAG until finger tight. Then back it off to align the long axis of the opening with the long axis of the sensor. You can then use the three Allen screws to tighten this down. Works with the Orion spacer too as there is a lip in the spacer.

As soon I get a chance to do some real star testing I will post more info.

Cheers!

Edited by Phillip Easton (09/17/13 09:34 AM)


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Phillip Easton
sage


Reged: 12/24/10

Loc: DFW
Re: New Orion "thin" OAG new [Re: Phillip Easton]
      #6085558 - 09/17/13 09:24 AM Attachment (65 downloads)

Here is a shot of the bottom of the autoguider mounting plate removed from the prism stalk. One Allen screw can only be accessed this way as the body gets in the way. Did this to align the sensor to the hole.

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Raginar
Post Laureate
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: New Orion "thin" OAG new [Re: Thirteen]
      #6085663 - 09/17/13 10:22 AM

Isn't there a 'thin' t ring out there? I thought scope stuff or agena had one. Does that other brand get you the correct spacing out of the box? Perhaps that is the best option?

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Thirteen
sage


Reged: 07/12/13

Loc: Milford, Michigan
Re: New Orion "thin" OAG new [Re: Phillip Easton]
      #6085725 - 09/17/13 10:57 AM

Ok this answers one of my questions. From that shot I see there is a little shoulder there on the bayonet mount (camera side) that stands the camera off the oag a bit. This is making more sense now. Thanks for the review and pics! This looks like it definitely adds more than the claimed 10.5mm.

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Phillip Easton
sage


Reged: 12/24/10

Loc: DFW
Re: New Orion "thin" OAG new [Re: Thirteen]
      #6085831 - 09/17/13 12:06 PM

Your welcome! The guider is 10.5mm in width. The Canon adapter adds a little. That shoulder is part of the adapter not the TOAG body if that helps.

I was using the Tele Vue Wide T-adapter, (http://www.telescope.com/Tele-Vue-Canon-Wide-T-Adapter/p/8849.uts?keyword=canon) and they are within ~1 mm of each other in width.

Cheers!


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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: New Orion "thin" OAG new [Re: Thirteen]
      #6086824 - 09/17/13 09:15 PM

Looks like the TS-OAG9 is 2mm less.

See diagram

http://www.teleskop-austria.at/information/zube-offaxis-ts/eos_TSOAG9.jpg


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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: New Orion "thin" OAG new [Re: Phillip Easton]
      #6086859 - 09/17/13 09:35 PM

Quote:

Your welcome! The guider is 10.5mm in width. The Canon adapter adds a little. That shoulder is part of the adapter not the TOAG body if that helps.

I was using the Tele Vue Wide T-adapter, (http://www.telescope.com/Tele-Vue-Canon-Wide-T-Adapter/p/8849.uts?keyword=canon) and they are within ~1 mm of each other in width.

Cheers!




My standard T-ring also has this shoulder, but it fully inserts into the camera, and adds no additional thickness. Is that the case here I wonder? If so we shouldn't be measuring from the top of the shoulder, but rather below it!

Does this shoulder disappear into your camera when inserted?

Edited by Wmacky (09/17/13 09:38 PM)


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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: New Orion "thin" OAG new [Re: Thirteen]
      #6087094 - 09/17/13 11:38 PM

A interesting discussion on this very topic (Thin OAGs, and Edge HD scopes)!

http://www.cloudynights.com/item.php?item_id=2878


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Raginar
Post Laureate
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: New Orion "thin" OAG new [Re: Wmacky]
      #6087554 - 09/18/13 09:17 AM

Good find, I forgot that one.

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Phillip Easton
sage


Reged: 12/24/10

Loc: DFW
Re: New Orion "thin" OAG new [Re: Raginar]
      #6087594 - 09/18/13 09:38 AM Attachment (27 downloads)

So the large shoulder does go into the camera. This is a standard Canon adapter. It also work with my Astronomik CLS-EOS clip filter in the camera. There is a very thin face plate on the adapter which is needed to engage the locking pin on the camera. Distance from the front of the camera to the front of the TOAG is probably around 11-12mm. I might have to get some calipers to measure it.


Cheers!

Edited by Phillip Easton (09/18/13 10:34 AM)


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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: New Orion "thin" OAG new [Re: Phillip Easton]
      #6088062 - 09/18/13 01:34 PM

This is good news! I think I'm now sold on this.

Any chance of another close up edge on pic like above, but showing the T-2 thread adapter installed into the 44 mm threads?

Edited by Wmacky (09/18/13 02:09 PM)


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Phillip Easton
sage


Reged: 12/24/10

Loc: DFW
Re: New Orion "thin" OAG new [Re: Wmacky]
      #6088234 - 09/18/13 03:05 PM Attachment (40 downloads)

Quote:

This is good news! I think I'm now sold on this.

Any chance of another close up edge on pic like above, but showing the T-2 thread adapter installed into the 44 mm threads?




Sure, here it is. I left off their nose piece it doesn't add to the width and if needed the top of the focuser would be flush to the T-adapter.

I don't have calipers but did the next best thing with a ruler to give you a better idea of actual width. I would say the whole thing is just around 13mm.

Hope this help and I hope all the images buy me some cloud free karma to try this puppy out


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Thirteen
sage


Reged: 07/12/13

Loc: Milford, Michigan
Re: New Orion "thin" OAG new [Re: Phillip Easton]
      #6088264 - 09/18/13 03:17 PM

Perfect... thanks so much. If I have karma to give, you got it.

This looks close enough to try with the standard edgehd t-adapter. I know I have seen zero effective length adapeters from M48 to T-thread available also, so this extra 2mm could probably be shed also, for a little more cost.

As it is, it still looks to be within the +/- 3mm of backfocus 'tolerance' Celestron is stating for the edges, so I think I am sold on this also.


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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: New Orion "thin" OAG [Re: Thirteen]
      #6088364 - 09/18/13 04:15 PM

Yes a thanks to both Smigol, and Phillip Easton for all the pics.
And:

Yes, agreed! I think it's going to work fine. It appears it to be even thinner than the TSOAG9-EOS. I'm putting in a order.How robust does it seem concerning the stalk to body connections? I know the Lacerta was favored over the TS-OAG in this regard.

OK, it's ordered. I will be using it with a 40D initially, along with a ASI120 as a guider. I guess I need the same guide camera spacer as Phillip?I'm thinking that instead of ordering the Orion t-thread spacer kit, I can substitute with this?
http://agenaastro.com/blue-fireball-t-thread-spacer-ring-4-5mm-extension.html


Edited by Wmacky (09/18/13 09:50 PM)


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Raginar
Post Laureate
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: New Orion "thin" OAG [Re: Wmacky]
      #6088796 - 09/18/13 08:22 PM

Can anyone tell me how wide the 'coma corrector' spacer is? I need like 5mm in my image train and I'm hoping that works.

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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: New Orion "thin" OAG [Re: Raginar]
      #6088966 - 09/18/13 09:51 PM

Quote:

Can anyone tell me how wide the 'coma corrector' spacer is? I need like 5mm in my image train and I'm hoping that works.




Orion lists it at 3mm


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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: New Orion "thin" OAG [Re: Wmacky]
      #6089172 - 09/18/13 11:35 PM

Thanks. Missed that!

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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: New Orion "thin" OAG [Re: Thirteen]
      #6089916 - 09/19/13 12:56 PM

BTW - If anyone else wants to try one, Here's a coupon for $10 off the OAG.

GRT213


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cherokawa
super member
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Reged: 10/19/08

Loc: Torrance, CA
Re: New Orion "thin" OAG [Re: Wmacky]
      #6090889 - 09/19/13 11:57 PM

What I'd be interested in knowing is how easy/difficult it is to find a guide-star with this and an SSAG.

The price is definitely right. If it works well with the SSAG, I might order one. But I'm worried that finding a guide-star would be a chore with my 150mm f/5 reflector.


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