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Equipment Discussions >> Cats & Casses

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zjc26138
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Reged: 02/24/05

Loc: Mingo Junction, Ohio
Re: New Celestron OAG Arrived! new [Re: end]
      #5964004 - 07/10/13 12:46 PM

That's great also. Hopefully it does arrive today. It's supposed to be clear Thursday-Sunday for me. So I should plenty of time to test it out.

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sage


Reged: 08/31/11

Loc: Houston, Texas, USA
Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5964555 - 07/10/13 06:44 PM

Mine just arrived! Here are some unboxing pictures:

http://triplehelix.rice.edu/~jdhartgerink/astronomy/oag_unboxing/


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sage


Reged: 08/31/11

Loc: Houston, Texas, USA
Re: New Celestron OAG Arrived! new [Re: end]
      #5964601 - 07/10/13 07:20 PM

The pictures linked above are probably more valuable than anything I'll say here, but I'm quite happy with the quality of the build. Fully assembled the system is very rigid and still allows for helical focusing of the guide camera and 360 degree rotation of the pickoff mirror to allow more flexible guide star selection.

The main reason I bought this system was to have an OAG that had the proper back focus for my canon out of the box rather than having to make compromises or purchasing a large number of adapters from third parties. On that front this is certainly a success. For people who have limited back focus distance available to them this is NOT going to be a good OAG to buy. It will also probably be difficult to work with filter wheels. But in my case with a Canon 60Da as the imaging camera and using Astronomic EOS clip in filters, it may be just about perfect.

Of course, all of this is meaningless unless the pictures come out looking good. Unfortunately tonight is the only night I have to test it before going out of town for three weeks... If I have the opportunity to do a first light, I'll post back here again.


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zjc26138
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Reged: 02/24/05

Loc: Mingo Junction, Ohio
Re: New Celestron OAG Arrived! new [Re: end]
      #5964893 - 07/10/13 10:45 PM

Glad your OAG arrived and I hope you are having a good first light! What scope are you going to use with it?

I agree that this system seems is robust. Plus it comes with a whole slew of adapters. I'm hoping for first light tomorrow night with my Edge 8, T1I, and SSAG.


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sage


Reged: 08/31/11

Loc: Houston, Texas, USA
Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5965001 - 07/10/13 11:45 PM

Well, no first light for me tonight. Ran into a problem with my mount and don't have the time to trouble shoot. Unfortunately that means a three week delay for me...

I'll be using this on an Edge 11, Canon 60Da and SSAG. The mount gave me problems just at the point where I had achieved focus in both the guider and camera... the fun was about to begin and now this. Oh well.

Good luck on your end!! It has to be better luck than mine!

By the way, I think there is an error in the manual that comes with the guider. If you look at the figure for setting up with an Edge 8 vs. an Edge 11, the suggested adapters are identical even though the suggested back focus is different. I confirmed that the figure for my Edge 11 gave the proper back focus distance, but you might want to actually measure the setup you get with your 8 because to me it looks like if you use their suggestion you are going to be too long and will want to use one of the shorter spacers.


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zjc26138
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Reged: 02/24/05

Loc: Mingo Junction, Ohio
Re: New Celestron OAG Arrived! new [Re: end]
      #5965685 - 07/11/13 01:18 PM

Sorry you didn't get first light. I still haven't tested the OAG in the daylight. I probably should that way I won't have an hiccups when I get clear skies.

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crow
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Reged: 07/09/12

Loc: BC, Canada
Re: New Celestron OAG Arrived! new [Re: end]
      #5966127 - 07/11/13 05:49 PM

Thanks for the pics, really helpful. Looks like a nice piece of kit.

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zjc26138
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Reged: 02/24/05

Loc: Mingo Junction, Ohio
Re: New Celestron OAG Arrived! new [Re: crow]
      #5967149 - 07/12/13 10:36 AM

First light was not the best, even though it was a gorgeous night. I could not find guide stars to save my life. I tired several targets and could not find any stars. I think the SSAG might not be sensitive enough. I'll try again tomorrow night. I'll put an eyepiece in the autoguider spot first and find stars, then give the SSAG a try. I did not do that last night.

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rmollise
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Reged: 07/06/07

Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5967297 - 07/12/13 12:10 PM

You will need to be close to focus to see much of anything. Best bet? Get a bright star on the guider prism and focus the camera on that.

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zjc26138
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Reged: 02/24/05

Loc: Mingo Junction, Ohio
Re: New Celestron OAG Arrived! new [Re: rmollise]
      #5967438 - 07/12/13 01:38 PM

Thanks for the advice Rod. It's supposed to be clear the next couple of nights, so I'll have a good amount of time to test it out.

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rmollise
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Reged: 07/06/07

Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5967677 - 07/12/13 03:36 PM

Quote:

Thanks for the advice Rod. It's supposed to be clear the next couple of nights, so I'll have a good amount of time to test it out.




It's a pain in the you know what to get a guide cam focused in an OAG, but you'll get 'er done. Me? I used one for years when I was doing film imaging. I'm too lazy to do so now.


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zjc26138
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Reged: 02/24/05

Loc: Mingo Junction, Ohio
Re: New Celestron OAG Arrived! new [Re: rmollise]
      #5967684 - 07/12/13 03:41 PM

Oh I know I'll get it to work. Just need patience. My main reason for the OAG? So I can get 3-4 minute subs at 2032mm fl, and so that I don't have to take so many pictures. So I'm lazy as well.

This picture is 97 sub frame, and just over an hour total integration: http://www.astrobin.com/full/47915/?mod=none

While I think its a great image, it would be nice only to have to take 20-15 subs.


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Alfredo Beltran
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Reged: 08/01/10

Loc: Bogota, Colombia
Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5968180 - 07/12/13 10:01 PM

Hi Zach

That's a good image. I have the same camera, unmodified on a C9.25 EdgeHD. I suggest you use a lower ISO and longer exposure times per sub.

How big is the aperture of the OAG when it is attached to the EdgeHD?

Best regards,

Alfredo


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freestar8n
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Reged: 10/12/07

Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5968535 - 07/13/13 04:24 AM

The moon is coming back and I recommend getting the OAG and imaging camera co-focused using the moon. In order to see faint guidestars on the guide camera you will need to have it well focused. You should also look in the guide port with your eyeball to make sure there is a clear view of the pupil.

Once it is focused you should be able to find random stars to guide on - and you can practice that way just guiding on a star and not trying to image a particular object. That would get practice with calibrating the guider, and allow you to see first results with OAG - which should be pretty good.

Then I recommend calibrating the OAG so you know how far away the center of the guide chip is from the center of the imaging chip - in arc-minutes. This will let you create a field of view indicator (FOVI) for a planetarium program like TheSky - and let you select an optimal guidestar around an object you want. Then you just need to pre-orient the oag angle so that when the object is centered on the main ccd, the guidestar will fall on the guide ccd.

The one trick to setting the angle is that it is 180 degrees from where it "should" be. If the guidestar is on the north side of the object, then - looking at the back of the 'scope (sct or refractor) with north up - you should have the guide port on the 'down' or south side. This is because the image is inverted.

To do all this more precisely I would make an angle readout on the back.

Much of this is described in a write up I did here.

Some people don't worry about pre-planning a guide star, and they just center the object and then use a very long guide exposure until they see stars to guide on. This may work for you and it would take less effort - but it still requires very good focus on the guider side. I prefer to guide on the brightest guidestar available - and I find that pre-planning one and dialing it in is easy and systematic.

Good luck -
Frank


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zjc26138
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Reged: 02/24/05

Loc: Mingo Junction, Ohio
Re: New Celestron OAG Arrived! new [Re: freestar8n]
      #5969341 - 07/13/13 05:26 PM

Alfredo- Thanks! Yeah I plan using ISO800 or ISO1600 with 3-4 minute subs once I get the guiding figured out. How big is the aperture? Do you mean the opening, where the camera attaches? If so the opening is the same size as the t-ring adapter which at measured to be 4.2cm.

Frank- Thanks for all the pointers! How do you calculate the distance between the center of the imaging chip and the center of the guide chip?


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Alfredo Beltran
sage


Reged: 08/01/10

Loc: Bogota, Colombia
Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5969391 - 07/13/13 06:03 PM

Quote:

Alfredo- Thanks! Yeah I plan using ISO800 or ISO1600 with 3-4 minute subs once I get the guiding figured out. How big is the aperture? Do you mean the opening, where the camera attaches? If so the opening is the same size as the t-ring adapter which at measured to be 4.2cm.





Hi Zach

That is exactly the size I was asking. If it has the same aperture of the T-adapter then it would cause no different vignetting.

Could you post some pictures of your setup?

Best regards

Alfredo


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zjc26138
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Reged: 02/24/05

Loc: Mingo Junction, Ohio
Re: New Celestron OAG Arrived! new [Re: Alfredo Beltran]
      #5969414 - 07/13/13 06:23 PM Attachment (28 downloads)

Alfredo,
Great! I'm glad I answered your question.

Here is a quick picture during daylight testing. The only one I've taken so far. I'll take a couple more tonight once I get everything setup.


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Alfredo Beltran
sage


Reged: 08/01/10

Loc: Bogota, Colombia
Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5969505 - 07/13/13 07:27 PM

Hi Zach

Thank you.

It looks very nice! If you can, post one showing the opening.

Seems like a must have accesory. Let us know how the StarShoot Autoguider works with it.

Best regards

Alfredo


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freestar8n
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Reged: 10/12/07

Re: New Celestron OAG Arrived! new [Re: zjc26138]
      #5969999 - 07/14/13 05:28 AM

There are a number of ways to measure the separation of the guide chip from the imaging chip, and the choice depends on whether or not you have software to plate solve the imaging camera to know its exact center.

The simple way is to orient the guide camera so it is north or south of the imaging camera. Find a bright star and center it on the imaging camera - and note the declination. Then move the scope in dec. until the same star is centered on the guide camera. Make sure you remove any dec. backlash as you do this - and note the change in declination. That is the offset.

If you can plate solve, then just center a known star on the guide chip and then take a few second exposure with the imaging chip. When you plate solve the image it will tell you the exact center of the image, ra/dec, and you can calculate the offset. Again it's best to have the guide camera directly north or south so the only change is in dec.

And note that all this setup stuff and calibration is only needed once per OTA - and after that the OAG usage should be more systematic.

For now the main thing is just to get both things focused accurately - and the moon is good for that since it is big and bright - and at "infinity."

Frank


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jsrj98
member


Reged: 02/21/08

Re: New Celestron OAG Arrived! new [Re: freestar8n]
      #5970335 - 07/14/13 12:35 PM

My new OAG is due to arrive tomorrow, so I'm excited to try it. My guiding rig, which worked well for refractors, has proven problematic for my Edge 8 (as I expected).

I currently own a QHY5 (same as Orion SSAG), but I'm worried it won't be sensitive enough. Are there any recommendations on a replacement? I'd love something like the Loadstar or ST-i, but they may be out of my price range at the moment. Does anyone have experience with the QHY5-II L mono-- it has a very high QE?

Thanks, John


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