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PGW Steve
Pooh-Bah


Reged: 10/03/06

Loc: Winnipeg, Canada
Re: The end of OAG? new [Re: vpcirc]
      #6136164 - 10/14/13 12:51 AM

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.


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Warhen
Vendor (IP4AP)
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Reged: 11/12/05

Loc: WV, USA
Re: The end of OAG? new [Re: vpcirc]
      #6145962 - 10/19/13 01:15 AM

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

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garret
sage


Reged: 07/26/09

Loc: Netherlands
Re: The end of OAG? new [Re: jaddbd]
      #6146283 - 10/19/13 09:38 AM

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

Garret


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SL63 AMG
scholastic sledgehammer
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Reged: 12/21/09

Loc: Williamson, Arizona
Re: The end of OAG? new [Re: Mike Wiles]
      #6146645 - 10/19/13 12:46 PM

Quote:

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



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.


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SL63 AMG
scholastic sledgehammer
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Reged: 12/21/09

Loc: Williamson, Arizona
Re: The end of OAG? new [Re: vpcirc]
      #6146657 - 10/19/13 12:57 PM

Quote:

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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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: SL63 AMG]
      #6146806 - 10/19/13 02:35 PM

IF you like OAG that's great Dave, I'm not bashing it, but I can tell you some of the best imagers at AIC I spoke to, would prefer not to deal with rotator other than when they want to use it. Of course, as I witnessed with Adam Block, they all take matching flats on a nightly basis, for illumination reasons because you are correct, the donuts aren't that much of an issue. They must do it on both sides of the meridian keep track if the shot was to the east or to the west. Mike Rice said if this works as advertised it's a godsend. At this point they're only getting ready to release for SCT owners, which SBIG said needed it more than anyone. I don't think I've seen a rotator option for a Celestron Edge, but they worked with Planewave and got all their specs on each OTA and hopefully will be rolling it out before mine is built. I cannot speak from experience, only trust Mr. Rice and others are telling me from their thoughts. I don't think this product is geared towards large RCOS owners, and would likely not be available anyway.

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Peter in Reno
Postmaster
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Reged: 07/15/08

Loc: Reno, NV
Re: The end of OAG? new [Re: SL63 AMG]
      #6147157 - 10/19/13 05:43 PM

+1 for OAG.

For the last few years imaging C-8 at 2000mm focal length, not ONCE I had to rotate OAG to find guide stars. No rotator is needed for me. Even after Meridian flipping, guide stars are always available in OAG's guide port. All is needed is a high sensitivity guide camera like Lodestar or ST-i and at least one usable guide star is always available especially in high light pollution area where I live. If you have an excellent mount, then increase guide exposure not only to brighten the guide stars but also to increase SNR.

OAG is getting extremely popular and there are many reports of people struggling to fix guide scope to main scope flexure issues have switched to OAG and swore to never go back to guide scope like myself. Once you get the hang of operating OAG, it's just as easy as guide scope. Another big plus for OAG is saving weight, easier balance and better ergonomics by eliminating guide scope.

I always take flats after each imaging session even if I didn't change camera's orientation. Better safe than sorry. You never know whether dust moved or added on CCD window or filters. It's so easy and quick to take flats. Flat is probably the most critical part of calibration with lights.

I am replacing C-8 with TEC 140 F/7 APO and I will still use OAG. It will be even easier to find guide stars due to shorter focal length or wider FOV.

Peter


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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: Peter in Reno]
      #6147222 - 10/19/13 06:25 PM

I'm sure SBIG hasn't done their research and has wasted years and 1000's on a problem that doesn't need to be fixed. Sorry I bothered to share it since it's pointless and OAG is the perfect answer for Sct's. I'll write the president of SBIG and let him know how foolish he's being!

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Peter in Reno
Postmaster
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Reged: 07/15/08

Loc: Reno, NV
Re: The end of OAG? new [Re: vpcirc]
      #6147316 - 10/19/13 07:24 PM

You were the one started the argument in your original post:

Quote:

By eliminating mirror issues, this seems like very promising new tech to end the pain of OAG and rotators for reflector systems.




Some of us are simply saying that operating OAG is NOT a P.I.T.A. to operate thanks to today's technology like high sensitivity cameras. Also I never need to use rotators as well.

If you had not mentioned the negatives about OAG, then I would kept it to myself and left this thread alone.

Peter


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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: Peter in Reno]
      #6147327 - 10/19/13 07:30 PM

The post was informational and believe it or not for some people it is a problem. It's amazing how some people can't let others look at what's being talked about without immediately saying its wrong. I'm sure the engineers at SBIG know what they're talking about, far more than anyone posting on CN.

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SL63 AMG
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Williamson, Arizona
Re: The end of OAG? new [Re: vpcirc]
      #6147356 - 10/19/13 07:47 PM

Quote:

I'm sure SBIG hasn't done their research and has wasted years and 1000's on a problem that doesn't need to be fixed. Sorry I bothered to share it since it's pointless and OAG is the perfect answer for Sct's. I'll write the president of SBIG and let him know how foolish he's being!




Mike,

I find it interesting that you are always "quoting" the best imagers and experts in the industry, but I have never once seen any of these poeple post themselves and back up your claims.

If you want to be an advocate for new products, fine, but at least try using them yourself first before making posts that are anectdotal at their core.

I don't think anyone has issue with you being the first to report a new product, it's just a little annoying when you make claims about a products fitness for merchantibility without having ever even tried it first.

If SBIG thinks this guider is going to replace OAG's in mass quantity, I think they are in for a wakeup call.

I tried guiding my 2857mm RCOS using my ST402ME on both a 250mm FL VarioFinder and a 650mm StellarVue SVRT 90mm Raptor and I can assure you that neither performed anywhere close to using the ST402ME or ST-i with my MMOAG at 2857mm FL.

Their system may work well with short focal length guiding but I don't see how it could become a feasible replacement for long focal length OAG guiding.


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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: SL63 AMG]
      #6147367 - 10/19/13 07:58 PM

Dave that's because most of them are in a private google group that's invitation only. They don't waste their time getting involved in silly pointless discussions on here like I do. Also, this system is not proven by any means. I saw the demo for it, I'm not advocating a brand.

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Raginar
Postmaster
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: The end of OAG? new [Re: vpcirc]
      #6147402 - 10/19/13 08:27 PM

Sorry everyone is attacking you, Mike. I think it's neat and if it gives us a new tool to work with, that'll be great.

Don't sweat it


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SL63 AMG
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Williamson, Arizona
Re: The end of OAG? new [Re: Raginar]
      #6147547 - 10/19/13 10:31 PM

Quote:

Sorry everyone is attacking you, Mike.




I dont get it.

Mike reports a new product.

Mike titles the product with an unlikely conclusion.

Mike then makes anecdotal statements about the likelyhood of the products performance and impact on competitive products though this product has not yet been released and he has never used it.

Mike repeatedly claims he is quoting well known people none of whom have ever publicly back up what he says.

People refute Mikes claims and back it up with facts.

You interpret it as a personal attack on Mike.

Perhaps Mike might consider evaluating his repeated "name dropping" anecdotal statements about things for which he has no personal experience and simply stick to the facts, then there will be no misperception of attacking him personally rather than his statements. Instead, we can simply discuss the merits of the information and products he wishes to share with us.

DISCLAIMER: This is not a personal attack on Mike.


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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: SL63 AMG]
      #6147850 - 10/20/13 04:16 AM

Dave there's a reason there's a question mark in the title. I was trying to share an item I saw at AIC that others might be interested in, as not everyone is as lucky as I to attend. I ask the questions of those who are far smarter than I, but they won't get dragged into stupid petty opinions from what one referred to as "armchair engineers" They gave their advice, take or leave it and do what you want.

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garret
sage


Reged: 07/26/09

Loc: Netherlands
Re: The end of OAG? new [Re: SL63 AMG]
      #6147851 - 10/20/13 04:18 AM

Quote:

Sorry everyone is attacking you, Mike. I think it's neat and if it gives us a new tool to work with, that'll be great.




Not every optical system has enough backspace for a OAG.
I have a newton astrograph, with the canon 5 dmk2; there is zero backfocus left.
The Wyne corrector has only 58mm of backfocus.
You can not even use a SBIG STX 16803 with filterwheel.

I'm waiting for this new guiding system due to guiding troubles, but placing a led near the imager is practically impossible without drilling a hole into the focusser

Garret van der Veen


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freestar8n
Post Laureate
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Reged: 10/12/07

Re: The end of OAG? new [Re: garret]
      #6147868 - 10/20/13 04:38 AM

Quote:

have a newton astrograph, with the canon 5 dmk2; there is zero backfocus left.





Hi-

Then you are definitely in the set of people who would benefit by guiding with a guidescope while avoiding flexure. You have a mirror system prone to flexure, and little backfocus.

In that case there is already a solution in the form of free software called FlexRX. It uses the Shift Guiding feature of MetaGuide to measure and compensate for motion detected in the arriving images. It is all based on free software, and it involves no hardware other than a video camera for guiding.

I am also a strong proponent of OAG and find it has little overhead in the imaging process, but I do aim for the brightest star available for guiding, and that does involve rotation on meridian flip and more flats - for best results anyway. If the OAG is far from the imaging chip, the difference in flats may be negligible.

But for certain systems such as Hyperstar and some Newtonians, OAG isn't practical and alternative solutions have uses.

I heard about this SBIG thing many years ago and expected they would face challenges getting it to work. A key issue is that it involves a moving centroid - which is unusual in autoguiding. For comet tracking MetaGuide also relies on a moving centroid - and I think it is the only software that guides with a moving centroid - and it has been doing so for many years.

Anyway - yes this device has been touted for years, and meanwhile there are already free software solutions for both flexure compensation without OAG, and comet tracking with or without OAG.

Frank


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Raginar
Postmaster
*****

Reged: 10/19/10

Loc: Rapid CIty, SD
Re: The end of OAG? new [Re: freestar8n]
      #6148099 - 10/20/13 09:53 AM

Dave, just look at your tone in your writing. Mike obviously isn't quite as versed on all the options as you are. He thought it was neat and shared it. I agree with him, it's neat and i can't wait to see it.

Kind of falls into the ONG area. I dunno if I need to buy one, who am I kidding, I'm a noob who barely can get data let alone make a pretty picture, but it's neat to see something new.

I get it, you think there isn't a problem to solve.


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SL63 AMG
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Williamson, Arizona
Re: The end of OAG? new [Re: Raginar]
      #6148266 - 10/20/13 11:40 AM

Quote:

Dave, just look at your tone in your writing. Mike obviously isn't quite as versed on all the options as you are. He thought it was neat and shared it. I agree with him, it's neat and i can't wait to see it.




You have hit the nail on the head.

There's no issue with him finding a product, thinking it's neat and sharing it. For that I am sure everyone is grateful, including myself.

The issue is that he doesn't just let it go at that. Instead he throws out anecdotal comments about the pain of OAG and rotating a camera, which provides a false impression to others who may find themselves in a situation where they need to have an OAG and may want to rotate their imaging camera. Mike does this often and I have decided that I'm not gong to sit back quietly and let it take place.

If that makes me unpopular in CN, so be it, but I know for a fact that I am not the only one that feels this way... I'm likely the only person that doesn't care if I'm unpopular for standing up and saying something about it.

If you think I'm wrong, click on Mike's nickname, then click on "show all user's posts", then see how many times he has been the very first response to someone's question and has provided subjective, rather than objective, responses to someones questions, many for which he has no personal experience.

I don't have issue with anyone wanting to be helpful, but I do have issue with stearing people down the wrong path when real money is involved.

Advice given hear needs to be objective, not subjective, so that people can make informative decisions about purchasing equipment to solve real issues.


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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: The end of OAG? new [Re: vpcirc]
      #6148361 - 10/20/13 12:42 PM

Quote:

Mike Rice said if this works as advertised it's a godsend.



I concur. The device takes us closer to point and shoot astrophotography. You can just slew to an object and start shooting.


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