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The end of OAG?

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#1 vpcirc

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Posted 12 October 2013 - 01:15 PM

I watched the president of SBIG demonstrate a revolution in a new guiding technology last night at AIC. Using the benefit of a wide field guide scope and the generation of an artificial star in the imaging train, the system measures changes in movements between the two to send guiding corrections. By eliminating mirror issues, this seems like very promising new tech to end the pain of OAG and rotators for reflector systems. They are also working on multi star guiding! SBIG has become my new favorite Astro company. It seems this system will be released in the very near future.

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#2 Footbag

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Posted 12 October 2013 - 01:20 PM

I watched the president of SBIG demonstrate a revolution in a new guiding technology last night at AIC. Using the benefit of a wide field guide scope and the generation of an artificial star in the imaging train, the system measures changes in movements between the two to send guiding corrections. By eliminating mirror issues, this seems like very promising new tech to end the pain of OAG and rotators for reflector systems. They are also working on multi star guiding! SBIG has become my new favorite Astro company. It seems this system will be released in the very near future.


Wow. The artificial star idea sounds very smart. I've always wondered about multi-star guiding as well. Thanks for sharing the info.

#3 vpcirc

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Posted 12 October 2013 - 01:21 PM

They're saying it will be announced within the next month

#4 Tapio

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Posted 12 October 2013 - 01:25 PM

Don't quite get it.
Looked at SBIG site and there was only "Sorry, there are no products at this time" in Differential Guiding.
Does this eliminate differential flexure using separate guide scope ?

#5 vpcirc

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Posted 12 October 2013 - 01:27 PM

Yes, no flexure

#6 mattw

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Posted 12 October 2013 - 01:52 PM

Very cool, thanks for posting. While I love my OAG for it's nice round stars, if I could forgo the rotator/OAG, and still avoid flexure, I would be sold.

#7 andysea

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Posted 12 October 2013 - 02:24 PM

That sounds very interesting! I don't quite understand how it works but I can't wait to learn all about it!

How is the artificial star generated?

#8 orion69

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Posted 12 October 2013 - 02:27 PM

So if I'm understanding this correctly they are measuring difference in position between artificial star and the actual guiding star in guide scope?
In another words they added another device to guiding scope just to accomplish same quality of guiding you would normally get from any OAG? ;)

#9 Rick J

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Posted 12 October 2013 - 03:05 PM

They've been "coming out" with this for several years now. I remember hearing it was only months away at least two years ago. Maybe this time they mean it. Sounds like there were more technical hurdles than they expected.

There are some things a OAG can't handle, tracking a comet for instance as it is in the field of view. True there is now a guider that can do that but it only works with chips smaller than Mike or I use. While the Paramount will track a NEO making a pass it does so based on its velocity at the start of the image run. With very close ones this is not good enough as the velocity changes too much even in 30 minutes time such that by the end of the run the asteroid is making short trails. This system could eliminate this issue. NEOs are usually bright enough to be seen in a guide scope at closest approach when this becomes an issue for me.

It will be interesting to see how well it lives up to its billing when it finally does come out. I'll be waiting for their reports before considering it however. Often takes a year or so to get complex things like this ready for prime time. No matter how much testing is done it seems users find glitches no tester came across.

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#10 vpcirc

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Posted 12 October 2013 - 03:06 PM

I'll see if they have a flyer and scan it

#11 andysea

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Posted 12 October 2013 - 03:41 PM

Thanks Mike! Keep us posted.

#12 vpcirc

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Posted 12 October 2013 - 07:48 PM

Sorry, no documentation, but everyone there said within the next 30 days it will be released. They were talking to Planewave about adapting it to each of their OTA's. It looked operational and I don't think they would of been highlighting it if it wasn't a reality. No commitment was made on multistar guiding that I heard.

#13 jaddbd

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Posted 12 October 2013 - 08:10 PM

Is that the "differential guiding" that they have been working on for a while?

Not sure if this is what they are talking about actually becoming a reality.

Here is a blurb:

Differential Guiding: SBIG has a patent pending on a new guiding technique using an artificial guide star. Although artificial stars are used in a variety of techniques on professional telescopes, the SBIG technique is somewhat different and easy to implement on amateur scopes. An artificial star is created near the focal plane of the imaging CCD and an image of this star is retro-reflected into a separate guide scope. By using one real star in the FOV of the guide scope and the artificial star image reflected from the main scope, the difference in separation caused by telescope pointing errors is used to make the corrections to the telescope drive. There is no problem with differential deflection and a single CCD external guider can be used to monitor both the real and artificial guide stars. The artificial star image is not seen by the imaging CCD.

and a diagram.

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#14 jaddbd

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Posted 12 October 2013 - 08:12 PM

And another...

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#15 vpcirc

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Posted 12 October 2013 - 08:54 PM

Yep that's what they said will be ready in 30 days

#16 Iver

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Posted 12 October 2013 - 10:11 PM

Toward the end of this youtube clip from NEAF last year they explain the product.
https://www.youtube....h?v=ti8wvBkF2U8

#17 pfile

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Posted 12 October 2013 - 11:00 PM

yes unfortunately the same prototype was at AIC last year, so i hope they are really getting it done.

but these guys know what they are doing, so i'm sure we'll see it soon.

#18 PGW Steve

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Posted 13 October 2013 - 12:22 AM

Sounds like a really neat technique. I can see the importance of not having tube currents in an SCT, I don't know how much the 'boiling' air in the tube will upset the artificial star.
Coming soon, chasing tube seeing and sky seeing. :-P

#19 Mike Wiles

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Posted 13 October 2013 - 01:10 AM

What benefit does this system offer over an off axis guider? An off axis guider is an awesome way to get rid of differential flexure, reduce weight and get spot on guiding at long focal lengths. With today's more sensitive guiding cameras, the old issue of finding a bright enough guide star for on OAG is all but eliminated as well.

While I applaud SBIG's effort and I'm a big fan of their products.....it seems like a million dollar solution to a 50 cent problem. It's heavier, more expensive and has more points of potential failure.

#20 vpcirc

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Posted 13 October 2013 - 08:14 AM

Mike for those using a rotator on their system this is a godsend provided it works as promises. They don't have to take flats for every angle that used during the night including flips. They don't have to rotate to find a guide star if they don't need to. It makes things far less complicated. If you're shooting with a refractor, yep, no value to you. In that case AP has come up the perfect solution, but I'm not here to argue what's better if you love OAG then that's wonderful, and why would you care. For those of us who want a different solution hopefully there's options.

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#21 PGW Steve

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Posted 13 October 2013 - 11:51 PM

I can see a big advantage in adaptive optics. With the wider field of a guide scope as opposed to an OAG through some 3 meter focal length CDK or RC or something, there should be a much higher probability of a bright star to allow the higher Hz values that make AO able to shoot through the seeing so to speak??
This is just my limited knowledge of AO at the time.

#22 Warhen

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Posted 19 October 2013 - 12:15 AM

Kudos to good friend and former imaging partner George Whitney for this new A-P product!

#23 garret

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Posted 19 October 2013 - 08:38 AM

The retro reflector may cause unwanted reflections or spikes...
The led near imaging camera mean I must drill a hole into the focusser?

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#24 SL63 AMG

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Posted 19 October 2013 - 11:46 AM

What benefit does this system offer over an off axis guider? An off axis guider is an awesome way to get rid of differential flexure, reduce weight and get spot on guiding at long focal lengths. With today's more sensitive guiding cameras, the old issue of finding a bright enough guide star for on OAG is all but eliminated as well.

While I applaud SBIG's effort and I'm a big fan of their products.....it seems like a million dollar solution to a 50 cent problem. It's heavier, more expensive and has more points of potential failure.


I agree on all these points. In fact, I recently changed the guider on my RCOS from an ST402ME to an STi because I had to move the imaging system closer to the OTA due to the addition of a field flattener. Considering the huge size of the FLI CL1-10 filter wheel, the ST402ME would hit the CL1-10 sitting on top of the MMOAG helical focuser. The STi sits perfectly down into the MMOAG helical focuser.

At first I was worried about having smaller pixels (7.4 micron vs. 9.0 micron), a smaller FOV (648x484 vs 765x510)and less sensitivity, but the Sti, rotated lengthwise to the OAG prism works flawlessly and I never have trouble finding an adequate guide star outside of the FOV of my 16803 chip.

Look at all the guide stars available in my FOV of NGC1491

Posted Image

Besides, why give up a perfectly good rotator which can be used not only for finding a guide star but also for framing an object.

Mike, it looks like you could have used a rotator for your example image. :foreheadslap:

#25 SL63 AMG

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Posted 19 October 2013 - 11:57 AM

Mike for those using a rotator on their system this is a godsend provided it works as promises. They don't have to take flats for every angle that used during the night including flips. They don't have to rotate to find a guide star if they don't need to. It makes things far less complicated. If you're shooting with a refractor, yep, no value to you. In that case AP has come up the perfect solution, but I'm not here to argue what's better if you love OAG then that's wonderful, and why would you care. For those of us who want a different solution hopefully there's options.


Mike,

You make it sound as if we're in agony using our OAG's and rotators.

Nothing could be further from the truth.

When I plan my imaging session I simply open TheSkyX, rotate my FOVI so that my guide chip lands on an appropriate guide star that provides me the best looking composition for the obejct I am imaging and send the position angle to CCDAutoPilot.

As far as flats are concerned, I can tell you from experience that taking flats at every position angle isn't really necessary. All of the dust donuts of concern produced by the imaging system are near the camera. If you look at any of my flats, you'll see that the small tight dark dust donuts are caused from dust on the camera glass cover, the larger fainter ones are caused by dust on the filters. Anything on the secondary or primary mirror is not visible in a flat, BUT, if it were, take sky flats at dusk and dawn at the same PA angle as the image you are capturing is simple. CCDAutoPilot does all the work and produces perfect flats every time.

There is nothing complicated about it.

Besides, guiding at focal length versus guiding at a fraction of focal length is a no brainer.

I'll keep my OAG and I'll bet every owner of a large long focal length reflector will do the same.






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