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Equipment Discussions >> Cats & Casses

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freestar8n
Post Laureate
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Reged: 10/12/07

Re: New Celestron OAG Arrived! new [Re: jsrj98]
      #5971111 - 07/14/13 07:59 PM

Hi-

I just posted a comparison of the QHY5L-ii with Lodestar in the ccd section. Yes, the qhy is very sensitive and works well with OAG - and in my case with MetaGuide.

Frank


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jsrj98
member


Reged: 02/21/08

Re: New Celestron OAG Arrived! new [Re: freestar8n]
      #5971369 - 07/14/13 10:50 PM

Thanks, Frank. Very interesting analysis comparing the QHY5L II to the Loadstar. I've always wanted to try MetaGuide but never had a guide camera that could use it. Perhaps this will be my chance.

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jsrj98
member


Reged: 02/21/08

Re: New Celestron OAG Arrived! new [Re: jsrj98]
      #5975817 - 07/17/13 11:37 AM

I wanted to report that I was able get my new OAG working last night. It took me quite awhile to figure out the correct spacing for use with my QHY5 guider. I initially used the moon to get the focus close, and then used an open cluster (M39) to fine-tune focus. In the end I needed 21mm of T spacers between the OAG and the guider (with the guider directly screwed onto the OAG). Celestron provides a variety of different spacers included in the package. I followed the instructions and used the ~11mm spacer between the OAG and the T-Ring for my DSLR (their math in the manual does check out in terms of the requirement for 133mm backfocus between OTA and camera for my Edge 8). Luckily had I had on hand a number of other smaller T spacers to to supplement the 6mm they suggest in the manual. It's possible the 24mm they include in the box would come to focus for the guider.

In terms of performance I was able to get just ever so slightly out of round stars at 5 min subs and more oblong stars with 10 min subs. I'm using a Orion Sirius EQ as a mount. I will probably need to check my polar alignment. Also, using PHD with such a long F/L guiding is very new to me, so I will need to do some experimentation on the various settings, I'm sure. My PHD "graph" was all over the place-- but perhaps that's normal? I'm used to using a short F/L guiding setup. However, in the end the FWHM for 5 min and 10 min subs was pretty close to that of a 10 sec sub, so I was pretty happy-- all in the range of the seeing conditions at between 3" and 2.5".


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freestar8n
Post Laureate
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Reged: 10/12/07

Re: New Celestron OAG Arrived! new [Re: jsrj98]
      #5979099 - 07/19/13 02:12 AM

Hi John-

Thanks for the report and I'm glad the OAG is working. It sounds like you were able to find guidestars. If you saw some out of round in 5m and they were more out of round in 10m, that does sound like field rotation and not a guiding issue but you would need to confirm. OAG should provide smaller stars - so other factors like field rotation will be more visible.

As for the "plot" - this alludes to some of the misconceptions about OAG and motivated design aspects of MetaGuide. If you look at the guide error in terms of pixels, it will change dramatically when you change the optics from a small guidescope to oag. An OAG guidestar error plot will look huge and noisy compared to a very quiet guidescope plot - but what really matters is how it looks in terms of arc-seconds. If the centroid is accurate, the plots should be no different when viewed in terms of arc-seconds - and the tuning should be the same also. In MetaGuide all displays and tunings are based on arc-seconds, which I consider the fundamental unit for autoguiding.

Unfortunately when people see this big and noisy oag plot - they think it is *worse* to guide on because it is "guiding on the seeing" or "chasing the seeing" or something. Instead it is providing a more precise measure of the star centroid, when scaled to arc-seconds - and that's a good thing.

I expect this improved guiding will show in your images once you get the polar alignment and other tunings optimized. Then you just need to focus well and you will be limited by seeing rather than guiding and flexure.

Frank


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jsrj98
member


Reged: 02/21/08

Re: New Celestron OAG Arrived! new [Re: freestar8n]
      #5979575 - 07/19/13 10:41 AM

Thanks for your input, Frank. I tweaked the polar alignment a bit and now I'm getting consistently round stars at 5 min. I do understand what you mean about the plot in terms of arc secs. Using my OAG the QHY5 is now guiding at 0.5" per pixel, a huge change from my previous setup-- which was over 6.0"! With that rig, my PHD graphs were always beautifully flat and consistent.

I have to say that I really like the Celestron OAG, as big as it is. It's really robust, and I could see hanging a lot of gear off it. The only conditions under which you might run out of backfocus with it (especially with the larger HD's 9.25 to 14) are if you wanted to add a regular focuser, and fix the primary.

BTW, my new QHY5L II arrives tomorrow so I'm hoping to try MetaGuide very soon. AstroFactors shipped my order the very next day!


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end
sage


Reged: 08/31/11

Loc: Houston, Texas, USA
Re: New Celestron OAG Arrived! new [Re: jsrj98]
      #6044944 - 08/25/13 10:40 AM

I have finally had a bit of time to work with my Celestron OAG. Not a lot of time, but enough to say that I'm very happy with the purchase. Last night, for example I was able to take six 480 second exposures with a focal length of 2800mm with perfectly round stars (well not perfect - my collimation and focus left something to be desired, but perfectly guided). Compared to my results using an Orion 400mm guide scope, this is a massive improvement. The only reason I didn't take more and longer exposures was that clouds rolled in and ended the night. Before this OAG I had purchased a Lacerta OAG and while I was able to get good long exposure guiding with that set up, the Celestron OAG is a much more versatile setup. The Celestron allows adjustment of the placement of the guider mirror in 360 degrees around the imaging field of view in addition to modest movement of the guide mirror in and out. It also allows easy rotation of the camera for framing shots. More important, in my opinion, is the helical focuser for the guide camera which makes focusing guide stars infinitely easier than the process for the Lacerta. So far I'm a very happy customer!

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NeoZavier
sage


Reged: 03/22/10

Loc: Puerto Rico
Re: New Celestron OAG Arrived! new [Re: end]
      #6061681 - 09/03/13 09:11 PM

Hi to everyone!
Jos to inform I recently bought the OAG from celestron and is amazing! But one horrible problem I found. I own the EdgeHD 8, this error wont happened in the other models of hd. I also bought the reducer for the 8 and the problem is with the back focus. On the 8 with the reducer the back focus is 105mm. The OAG is designed to work on a 133mm back focus that means I can only use it at f/10 so I returned. This wont happened on the other models because the 11hd and 14hd have 146mm of back focus. This is a horrible problem but everyone owning a Edge HD 8 has to know!


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jsrj98
member


Reged: 02/21/08

Re: New Celestron OAG Arrived! new [Re: NeoZavier]
      #6061851 - 09/03/13 10:53 PM

I haven't purchased the new Edge8 FR yet, but when I do, I'm planning to connect it to the scope using this adapter:

http://agenaastro.com/blue-fireball-sct-female-m48-male-thread-adapter-c-04.html

I've done the math and the resulting backfocus will be very close to (+-2mm) the 105mm spec.


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NeoZavier
sage


Reged: 03/22/10

Loc: Puerto Rico
Re: New Celestron OAG Arrived! new [Re: jsrj98]
      #6063120 - 09/04/13 05:49 PM

Interesting I would have to see the difference. But still it has to have the male and it has to be short too.And if u use a DSLR it has to sum the distance to the sensor that is 55mm or so. If you are using a CCD you wont have this problem.

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Wmacky
Carpal Tunnel
*****

Reged: 11/24/07

Loc: Florida
Re: New Celestron OAG Arrived! new [Re: jsrj98]
      #6315703 - 01/16/14 12:23 AM

Quote:

I haven't purchased the new Edge8 FR yet, but when I do, I'm planning to connect it to the scope using this adapter:

http://agenaastro.com/blue-fireball-sct-female-m48-male-thread-adapter-c-04.html

I've done the math and the resulting backfocus will be very close to (+-2mm) the 105mm spec.




brought this thread back looking for an update:

Has anyone tried this adapter or resolved this issue of the wrong backfocus distance when using this OAG with a reducer on a C8 Edge.

Also, is there a place to install a 2" LPS filter?

Edited by Wmacky (01/17/14 12:48 AM)


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ZR1
member


Reged: 01/13/14

Loc: San Francisco Bay Area
Re: New Celestron OAG Arrived! new [Re: Wmacky]
      #6317050 - 01/16/14 05:47 PM

Is this new adapter for the OAG going to make much of a difference when it is available in April? It looks like it has a larger aperture.

http://www.celestron.com/astronomy/off-axis-guider-adapter.html


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ewave
Pooh-Bah
*****

Reged: 05/16/09

Loc: northwest NJ
Re: New Celestron OAG Arrived! new [Re: ZR1]
      #6317129 - 01/16/14 06:38 PM

Quote:

Is this new adapter for the OAG going to make much of a difference when it is available in April? It looks like it has a larger aperture.

http://www.celestron.com/astronomy/off-axis-guider-adapter.html




I am interested in this item, but cannot find information on the thread specs on either side. It's as if Celestron has this hidden.....


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Peter in Reno
Postmaster
*****

Reged: 07/15/08

Loc: Reno, NV
Re: New Celestron OAG Arrived! new [Re: ewave]
      #6317169 - 01/16/14 06:57 PM

It looks like one side of the new adapter screws into the rear cell of SCT (EdgeHD 9.25 or larger) using larger threads (probably 3.5") instead of much smaller SCT threads.

The other end of the adapter simply connects to the input or telescope side of Celestron latest OAG. This connection uses "dovetail" and is held by three screws of OAG, no threads and still rotatable. All you need to know is the opening or clear aperture of this adapter and it's 62.7mm or 2.47" as stated at the web site. The larger opening allows to fully illuminate the prism of OAG so the guide star can be brighter and easier to find.

The camera side of OAG uses the same supplied camera adapters that already came with OAG. The largest opening is M48 which is just under 2" and big enough for larger format cameras.

Download the OAG manual from Celestron web site. On pages 2, 4 and 5, you will see a picture of "SCT Adapter". This SCT adapter is replaced by the new larger adapter.

Hope this is clear.

Peter


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ewave
Pooh-Bah
*****

Reged: 05/16/09

Loc: northwest NJ
Re: New Celestron OAG Arrived! new [Re: Peter in Reno]
      #6319248 - 01/17/14 06:50 PM

Quote:

It looks like one side of the new adapter screws into the rear cell of SCT (EdgeHD 9.25 or larger) using larger threads (probably 3.5") instead of much smaller SCT threads.

The other end of the adapter simply connects to the input or telescope side of Celestron latest OAG. This connection uses "dovetail" and is held by three screws of OAG, no threads and still rotatable. All you need to know is the opening or clear aperture of this adapter and it's 62.7mm or 2.47" as stated at the web site. The larger opening allows to fully illuminate the prism of OAG so the guide star can be brighter and easier to find.

The camera side of OAG uses the same supplied camera adapters that already came with OAG. The largest opening is M48 which is just under 2" and big enough for larger format cameras.

Download the OAG manual from Celestron web site. On pages 2, 4 and 5, you will see a picture of "SCT Adapter". This SCT adapter is replaced by the new larger adapter.

Hope this is clear.

Peter




Many thanks


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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: New Celestron OAG Arrived! new [Re: Wmacky]
      #6319282 - 01/17/14 07:13 PM

Quote:

Quote:

I haven't purchased the new Edge8 FR yet, but when I do, I'm planning to connect it to the scope using this adapter:

http://agenaastro.com/blue-fireball-sct-female-m48-male-thread-adapter-c-04.html

I've done the math and the resulting backfocus will be very close to (+-2mm) the 105mm spec.




brought this thread back looking for an update:

Has anyone tried this adapter or resolved this issue of the wrong backfocus distance when using this OAG with a reducer on a C8 Edge.

Also, is there a place to install a 2" LPS filter?




Anyway......


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Alfredo Beltran
sage


Reged: 08/01/10

Loc: Bogota, Colombia
Re: New Celestron OAG Arrived! new [Re: Wmacky]
      #6319431 - 01/17/14 08:55 PM

Quote:



brought this thread back looking for an update:

Has anyone tried this adapter or resolved this issue of the wrong backfocus distance when using this OAG with a reducer on a C8 Edge.

Also, is there a place to install a 2" LPS filter?




Anyway......




When I bought the C9.25 Edge I chose the adapter manufacturer by Starizona instead of the Celestron because it allows to place 2" filters and except that is exactly the same one as you can see here.

But it would be good to know also if the OAG has an adapter to place the 2" filters after the prism.

Best regards,

Alfredo


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jsrj98
member


Reged: 02/21/08

Re: New Celestron OAG Arrived! new [Re: Wmacky]
      #6321063 - 01/18/14 06:36 PM

I finally purchased the Edge8 0.7x FR to use with the Celestron OAG, and it arrived last week. I THINK my strategy of using the SCT to M48 adapter will work. Unfortunately, after one night of testing I determined that I got a bad FR, and I sent it back to the vendor for a replacement. Using a DSLR, 2/3 of the field was perfectly corrected, with pinpoint stars to the very edge-- from top to bottom. This was using the standard Celestron T-Adapter, so I know the 105mm backfocus was correct, as well as with the OAG. However 1/3 showed oval stars. I sent pics to the vendor and they agreed with my assessment and are sending a new one. Once I receive it and test I will post images.

ETA: I don't think there's a way to use a 2" filter with this combination. Although there might be some creative way to do that.

Edited by jsrj98 (01/18/14 06:40 PM)


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Wmacky
Carpal Tunnel
*****

Reged: 11/24/07

Loc: Florida
Re: New Celestron OAG Arrived! new [Re: jsrj98]
      #6321199 - 01/18/14 08:20 PM

Quote:

I finally purchased the Edge8 0.7x FR to use with the Celestron OAG, and it arrived last week. I THINK my strategy of using the SCT to M48 adapter will work. Unfortunately, after one night of testing I determined that I got a bad FR, and I sent it back to the vendor for a replacement. Using a DSLR, 2/3 of the field was perfectly corrected, with pinpoint stars to the very edge-- from top to bottom. This was using the standard Celestron T-Adapter, so I know the 105mm backfocus was correct, as well as with the OAG. However 1/3 showed oval stars. I sent pics to the vendor and they agreed with my assessment and are sending a new one. Once I receive it and test I will post images.

ETA: I don't think there's a way to use a 2" filter with this combination. Although there might be some creative way to do that.




Thanks for the update. Sure seems to be a lot of defective FR for the Edge8! Hmmmmmm. Anyway, that's too bad about the 2" filter. No LPS, and no HA narrowband.


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Thirteen
sage


Reged: 07/12/13

Loc: Milford, Michigan
Re: New Celestron OAG Arrived! new [Re: jsrj98]
      #6437969 - 03/30/14 03:40 PM

Quote:

I finally purchased the Edge8 0.7x FR to use with the Celestron OAG, and it arrived last week. I THINK my strategy of using the SCT to M48 adapter will work. Unfortunately, after one night of testing I determined that I got a bad FR, and I sent it back to the vendor for a replacement. Using a DSLR, 2/3 of the field was perfectly corrected, with pinpoint stars to the very edge-- from top to bottom. This was using the standard Celestron T-Adapter, so I know the 105mm backfocus was correct, as well as with the OAG. However 1/3 showed oval stars. I sent pics to the vendor and they agreed with my assessment and are sending a new one. Once I receive it and test I will post images.

ETA: I don't think there's a way to use a 2" filter with this combination. Although there might be some creative way to do that.




Thread resurrection!

I've been shopping around and really feel this setup would be the best way to use an OAG and the edge .7 FR. It's been a few months, do you have an update on it? I haven't purchased either yet. As far as I can tell, a lot of these Celestron Focal reducers get sent back. I am really considering pairing the Lepus HD telecompressor. With adapters it may cost more, but us Edge 8" owners need something that works. It's not like we are trying to do something extraordinary.


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