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Peter in Reno
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Reged: 07/15/08

Loc: Reno, NV
Re: The end of OAG? new [Re: garret]
      #6148366 - 10/20/13 12:47 PM

Quote:

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




Hi Garret,

QSI 683wsg with integrated filter wheel and OAG has back focus of 50mm to 53mm depending on T-thread or 2.156" adapter. Wouldn't this camera work?

Peter


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vpcirc
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Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: garret]
      #6148402 - 10/20/13 01:04 PM

Garret, if I understood SBIG correctly, these have to be engineered to the OTA, so I don't know that they would sell one that had you drilling to mount it. It looks like Frank has a good solution for you. Again, at this point this has yet to be proven in the field by users so I wouldn't bet on this being your solution yet. As Rick stated, they've been working on this for a few years, so it appears to be more complicated than we know. I am not advocating the product only sharing what I saw. I hope it works as advertised.

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mikeschuster
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Reged: 08/25/11

Loc: SF Bay area
Re: The end of OAG? new [Re: vpcirc]
      #6148418 - 10/20/13 01:12 PM

A couple of possible issues:

I believe SBIG mentioned using an IR light, which requires a filter on the main camera. If there are other telescopes nearby, it is important that any scattered IR light not affect them.

The retro-reflector mounted at the front of the tube is a source of potential flexure. So flexure remains an issue with this design.

Guide camera exposure time varies due to several factors (guide scope size, guide star magnitude, seeing conditions, etc.). Presumably an IR intensity control will also be necessary.

Thanks,
Mike


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orion69
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Re: The end of OAG? new [Re: Alph]
      #6148493 - 10/20/13 02:02 PM

Quote:

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




You can just slew to an object and start shooting only with high end mount without guiding. So, no it does not.

As mentioned before, this device could be usable if there is not enough backfocus for OAG.


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Wmacky
Carpal Tunnel
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Reged: 11/24/07

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Re: The end of OAG? new [Re: vpcirc]
      #6148499 - 10/20/13 02:08 PM

Quote:

most of them are in a private google group that's invitation only.




Well aren't they fancy....


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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: The end of OAG? new [Re: orion69]
      #6148513 - 10/20/13 02:26 PM

Quote:

You can just slew to an object and start shooting only with high end mount without guiding. So, no it does not.




It just happens that I own one of those mounts you are alluding to and they don't work that way. They require a lot of setup time and in the end you end up auto-guiding anyway.


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vpcirc
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Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: Wmacky]
      #6148516 - 10/20/13 02:30 PM

I think you misunderstand. They don't get into discussions about processes and procedures, they just share images. That's where they're interest lies, it's has nothing to so with being "special" Dave wanted to know why didn't chime in here. For great technical questions Ron Wodaski runs a great useful group on yahoo ccd-newastro with 4000+ members. His group is private too, but he lets folks in with a request. Most of these guys post their contact info on their web sites and gladly answer questions and help people. They do not however spend their time cruising Astro sites chiming in on every post.

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Hilmi
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Re: The end of OAG? new [Re: vpcirc]
      #6148570 - 10/20/13 03:13 PM

Dave,

In response to your post on page 2 of this discussion.

Those of us with high light pollution and long f ratios do find OAG a pain to use. I have had many targets where I could not find a guide star when I used to image at f10. This is one of the reasons I moved to f8. In light polluted skies even a reasonable guide star is sometimes not very effective.

I agree that a good rotator with an OAG is an idea that appeals to me and I am in fact considering making such a purchase but I believe there is a market for those who find OAG don't work well with their setups.

Different horses for different races. Besides, an experienced company like SBIG will not spend the money researching a product if they did not feel there was a solid business case for it.


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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]
      #6148672 - 10/20/13 04:30 PM

Quote:

Dave wanted to know why didn't chime in here. [sic erat scriptum]




Please don't put words into my mouth. I never asked why "they" don't chime in here. I am fairly confident I already know the answer to that question.

I merely pointed out that you frequently refer to individuals and groups of individuals to back up your anectdotal comments and those referenced never say the same things as you say.

Of course you have now isolated "them" even further into this elite group of demigods that wouldn't dare mingle with us mere mortals.

I'm sure glad we have you as "their" liason.

What's most interesting about this whole thing is that we have exactly the same situation in Amateur Radio. The elitists, the liasons and the rest of us.

What an awesome society in which we live!


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vpcirc
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Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: SL63 AMG]
      #6148728 - 10/20/13 05:13 PM

I did anything but isolate them Dave. I learn from them because I take the time to contact and ask the questions . Like most imagers they will help anybody at any time. I don't just spout off. Almost every question asked here is one I had myself. I seek the advice from those who have paved the road before me. Don't worry Dave, there's no room to put words in your mouth, there seems to be something in the way.

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Raginar
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Reged: 10/19/10

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Re: The end of OAG? new [Re: SL63 AMG]
      #6148765 - 10/20/13 05:39 PM

Dave,

That's your opinion of OAG guiding.. I'm just dabbling in it and so far it's been frustrating for me (all user generated I assure you). I guess if I had something like star lock that worked perfectly with my random conglomeration of scopes I have... I'd be stoked and might buy it.



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Peter in Reno
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Reged: 07/15/08

Loc: Reno, NV
Re: The end of OAG? new [Re: Raginar]
      #6148875 - 10/20/13 06:36 PM

Some people are missing the point about OAG. The reason OAG is mentioned in this thread is the OP mentioned it in the first post and title of this thread as being a P.I.T.A. to operate. If he had left it out and only mentioned SBIG's new flex free guide scope, compared with ordinary guide scopes and nothing else, this thread would not have gone viral.

I was in the same boat as Dave. Long time ago I started imaging with C-11 (2800mm focal length) and guide scope and I had nothing but trouble thanks to mirror flop inside the scope. I threw out the guide scope and replaced it with OAG/Lodestar and viola no more image shifts in between subs. Not only that, at least one guide stars have always been found in OAG guide port and NEVER had to hunt for guide stars by rotating OAG thanks to high sensitivity Lodestar. This is my hard fact and objective words about OAG. I live in extremely high light pollution area and I am very surprised I have not had a single issue with OAG and Lodestar.

I am very sorry that OAG has not worked quite well for Hilmi. Maybe he can start a new thread describing his issues and possibly someone will provide a good solution.

I now own a TEC 140 F/7 APO refractor but will still use OAG since I know how to operate it and why risk using guide scopes when there's a better chance of flexure?

Probably the most common mistake when people could not get OAG working is they use insensitive guiders like Orion SSAG.

Frank is correct about some disadvantages of OAG like it won't work for Hyperstar and some Newts with very short back focus. That's fine for Hyperstar since focal ratio is extremely small (or fast) and sub-exposures are also very short that any small guide scope would very well.

If the OP removes any negative comments about OAG in the original post, then discussions about OAG may stop. Discussions about OAG will never stop here until the OP removes negative comments in his first post and title of the thread.

I agree with Dave that discussions should always be objective.

To OP, if you remove any negative comments about OAG in the first post and title of this thread, I promise not to mention OAG from then on.

Finally, my comments do not in any way bash SBIG's new flexure free guide scopes. In fact I welcome this new technology. I never said that using OAG is easy. Quite the opposite. It takes time for some people to grasp the concept of using OAG. I also admit using guide scope is easier but not necessarily better than OAG. Please understand my reluctance of replacing OAG with guide scope.

Peter


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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]
      #6148927 - 10/20/13 07:10 PM

Quote:

I don't just spout off.




Quote:

Save your money and go with the 5. I don't know to many people using a 3 on SII




Supporting Thread


Quote:

Here's what Don told me at the Advanced Imaging conference. The greater the light pollution your dealing with the lower the number you want. I'm in the country with 4.5 skies, so I could use the 5nm. Had I been closer to town with more light pollution I would have coughed up the extra for the 3nm. I don't think you can get much better than the AstroDon E2's. I did my research and there's nothing close to para focal as they are. That does come at a price though.




Contradictory Supporting Thread


Would you like me to post a couple dozen more examples just like it?


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PGW Steve
Pooh-Bah


Reged: 10/03/06

Loc: Winnipeg, Canada
Re: The end of OAG? new [Re: SL63 AMG]
      #6148995 - 10/20/13 07:44 PM

Is it possible to just disagree with someone and state your point without turning it into a thread with more information on discrediting them than there are facts about the topic at hand?
I'm glad the OP shared information on a new technology. How that technology is applied, and how good/bad it is remains to be seen. As someone stated, it is unlikely SBIG did this just to waste R&D money, obviously there is a reason for it, AND a demand. Until there are working systems, with tangible results of the pros and cons of this system in real life imaging systems, EVERYONES opinion is just that. Perhaps we can carry on this discussion about Differential Guiding (DG) when there has been a suitable demonstration of its features via youtube, or a reputable imager that isn't an employee of SBIG.

Talk about shooting the messenger, this thread has brought out the bad in some people.


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Peter in Reno
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Reged: 07/15/08

Loc: Reno, NV
Re: The end of OAG? [Re: PGW Steve]
      #6149056 - 10/20/13 08:36 PM

The OP made very poor statement in his original post by making poor comparison with other technology like OAG. This is not about bashing or disagreeing with SBIG's new technology of flexure free guide scope. Dave and I actually welcomed this new technology. It's simply the way the OP made comments very poorly in his original and subsequent posts, that's all.

Please carefully read what Dave and I are trying to say. We did not bash or disagreed with SBIG's new technology of flexure free guide scopes. I just wished the OP simply had stated about SBIG's new but untested technology and nothing else.

Peter


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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: The end of OAG? new [Re: Peter in Reno]
      #6149625 - 10/21/13 10:46 AM

I don't think he did. He made an opinion, just like you are right now. I'm just learning how to setup an oag, and it's not easy like my finder guider. So, it's a PITA.

Again, you guys are just attacking poor Mike over a very small part of his post. Who cares if mike thinks a OAG is a PITA? The thread is about the new tech.


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Peter in Reno
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Re: The end of OAG? new [Re: Raginar]
      #6149679 - 10/21/13 11:26 AM

You are correct that the OP made an opinion and I simply rebutted his opinion. For that I am sorry that I didn't presented in a diplomatic manner.

I believe a better comparison would be to compare to typical guide scopes that has difficulty keeping in sync with the main scope since OAG do not have flexure issues. Primarily I believe this is supposed to replaced ordinary guide scopes, secondary for OAG.

Back to original thread. Did the speaker mention anything about software or will it still work with popular guiding software like PHD or MaximDL? What about dithering? After each dithering, will it have to re-calibrate the artificial star with guide star since the guide star moved due to dithering? I saw a Facebook video of the presentation but I am deaf and cannot hear what the speaker said.

I hope with time and experience from SBIG or other companies will come up with a much simpler design of same idea and universal to work with any scopes (Newt, Refractor, SCTs, etc.) to keep the cost down. Yes, I admit that guide scope is easier than OAG and am willing to try if I can get convinced it will work as well as OAG and guaranteed to get round stars for every sub like my OAG does.

Peter


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mikeschuster
super member


Reged: 08/25/11

Loc: SF Bay area
Re: The end of OAG? new [Re: Peter in Reno]
      #6149713 - 10/21/13 11:48 AM

Quote:

What about dithering? After each dithering, will it have to re-calibrate the artificial star with guide star since the guide star moved due to dithering?
Peter




I was at the presentation, these topics were not discussed.

As the system flexes, the IR star shifts with respect to the background stars. The IR star may collide and overlap with a background star, which will compromise measurement and differential guiding accuracy. Similarly with dithering.

Also, the positions of the chosen guide star and IR star may be widely separated. This will require a larger guide box size, increasing download times. There may be a need to reposition the IR star, to position it closer to the guide star, but any mechanical adjustability is an additional source of potential flexure. Also, issues like these will make the system harder to use that it otherwise might appear.

An automated setup (ACP, CCDAutopilot, etc) may need to deal with these issues. Positioning the IR star, making sure it does not collide across flexure and dithering, and resetting the intensity of the IR source to match the automatically selected guide star exposure are all issues that may required software development and ASCOM and/or custom interfaces.

Regards,
Mike


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vpcirc
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Reged: 12/09/09

Loc: Merced CA
Re: The end of OAG? new [Re: Peter in Reno]
      #6149742 - 10/21/13 12:02 PM

If I can make a few points to clarify
1. I posted this to share the new tech with others as not everyone is as fortunate as I to attend AIC.
2. I am not advocating or anyway saying that SBIG has found a solution but am hopeful.
3. My statement about OAG being a pain came directly from Mike Rice who runs NM Skies and has set up systems expertly for 20+ years. I am buying a new planewave 14 (hopefully) and SBIG is working with them to incorporate the new system. When I told Mike that, he said that's great you won't have to deal with the problem of OAG and rotation.
4. I believe that OAG is an absolute necessity in some cases
5. The president of SBIG said this system was most beneficial to SCT owners and that's why they were pursing that system first. I am not an expert nor have I tried to use OAG with an SCT so I have no clue why he feels that way.
6. The second part of the post with AP's new setup for refractors is a far better solution to OAG. AP makes some of the best refractors in the world, and again, if Roland didn't think this was a brilliant idea, it wouldn't be offered. I've used a similar setup for 4 years, but not nearly as secure and stout as they did, and yet I can guide perfectly for 30 min with my inferior system that Roland let me know I had mounted at the wrong point lol.

When I express my opinion, it is from my own experience of learning and asking questions from those much smarter than I and my own failures. I am far from always being right and many times there's more than one way to do things. My only goal is try and help others learning to not repeat my mistakes and make the journey through this learning curve easier. Yes, I seek out the advice of the best and the brightest, had I not, the telescope would be sitting in the closet gathering dust as I would of given up. I'm not bright enough to figure it out on my own.
Anyone that knows me personally will tell you I'd do anything to help another imager, not because I think I'm smarter or better, its just the way most of this community is.


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garret
sage


Reged: 07/26/09

Loc: Netherlands
Re: The end of OAG? [Re: Peter in Reno]
      #6149771 - 10/21/13 12:15 PM

Quote:

QSI 683wsg with integrated filter wheel and OAG has back focus of 50mm to 53mm depending on T-thread or 2.156" adapter. Wouldn't this camera work?






I want to use 35x24mm ccd arrays...because it give me a large field.
My 5 dmk2 has a coolerbox (-22 Celsius inside) the imaging result are very good only limited by seeing, light-pollution, and poor guiding (I'm working on this: new guider telescope, PEC for mount etc.)


Garret van der Veen


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