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#26 nemo129

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Posted 26 March 2011 - 07:05 PM

Multi Purpose Coma Corrector

Check here.

It's made by Baader. I do not image with a newt either, almost, but I bought an AT8RC instead! Like Falcon though, I have heard lots of good things about the MPCC.

#27 bluedandelion

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Posted 26 March 2011 - 08:32 PM

I agree with Sean (Falcon) and Kirk. Enjoy the scope. You will love it and be glad that you did not go for anything bigger. I have a 9.25 inch SCT on an Atlas that is right on the upper limit for AP in my estimation. With an MPCC you will have an excellent imaging platform.

Ajay

#28 Duncan Kitchin

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Posted 28 March 2011 - 10:09 AM

I'm using a Canon XS (1000D?). I have been looking at getting a coma corrector, but there is a lot of them to chose from lol. I also ordered the Orion Awesome Autoguider Refractor Package along with it. Hopefully this set up will hold me over for the time being anyway.


That should be a great setup - you'll have lots of fun with that. I used a Baader MPCC with my 6" Newt, and found it to work very well.

Regards & Clear Skies
Duncan

#29 locod1

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Posted 27 April 2011 - 08:26 PM

OK, so I'm sitting in my living room gazing at my New atlas mount with the 8" f/4.9 newt that just came in Monday and Tuesday. I am still waiting on one more 11lb. counterweight. Now I'm wondering what would be the best way to attach my un-forked meade 8" sct OTA to the atlas mount. I need something on the cheaper end as I have already spent more money than my better half allotted me!

#30 locod1

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Posted 27 April 2011 - 08:42 PM

Sorry, I have to list the new equipment. Can't hold it in.
Orion Atlas w/ 8" f4.9 newt
Astro-Tech 72mmED
William Optics 2" Carbon Fiber Dielectric Diagonal
2" SCT Focuser - Crayford Dual Speed
Bahtinov Focus Mask
F/6.3 SCT Focal Reducer
Orion Awesome Autoguider Refractor Telescope Package
So you can see why the wife might be a little upset, but when I told her It was all "around $1500" she calmed down.
now I just have to figure out how to tell how just how "round" that was...........

#31 Ranger Tim

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Posted 28 April 2011 - 08:00 AM

The Baader MPCC is a very nice corrector. Stars away from the center of view are much less "seagull" shaped and the corrector provides a convenient method of inserting the camera rig into the 2 inch focuser. A low profile focus tube adapter is not necessary with the MPCC - simply screw the MPCC onto the T-ring, attach camera and insert into focus tube. There is a flange on the MPCC to prevent the rig from falling too far into the tube. Spacing is generally not an issue with a DSLR.

#32 Bill W.

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Posted 28 April 2011 - 08:25 AM

You made a great choice with the Atlas. Mine has been a great performer. I have the AT8IN. It's a good match. I would also suggest at some point upgrading to a Losmandy head for your Atlas. ADM makes the dovetail you need to mount your Meade and also makes a dual Losmandy/Vixen head for the Atlas. Email Anthony at ADM if you have any questions. He makes quality stuff and is very knowledgable. Check out my webpage at the link at the bottom of the page. I have a Meade 8" SCT mounted with ADM dovetails.

http://admaccessories.com/

-Bill

#33 Patrick

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Posted 28 April 2011 - 09:44 PM

I just bit the bullet, and purchased the Atlas 8 EQ-G GoTo Reflector Telescope.



I have a personal dislike for EQ mounted Newts (sorry to be so blunt), but on the other hand, you can't go wrong with the Atlas mount, 8" of aperture, and an f/4.9 focal ratio (as you well noted).

Back to your original problem: " i have been taking some simple exposures of M42, and in almost every one i have misshaped stars. I not im not tracking perfect and I expect some trails, but the zig zag can only come from vibration? " While mount vibration could very well be a major contributor, I think a large factor is likely plain old periodic tracking error combined with the long focal length 8" SCT.

I'm assuming you were not autoguiding with your LX50 and I want to throw out a cautionary note regarding your new mount. Even though I'm sure the Atlas will be much (very much) better than the LX50 mount, I think you'll find you'll still need to autoguide with the 1000mm focal length reflector. If astrophotography is really the main goal, you might want to consider putting an autoguider in your budget.


Patrick

#34 Bill W.

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Posted 29 April 2011 - 08:28 AM

I agree with Patrick about autoguiding. To cut costs, you can make a guidescope out of a 50mm finderscope and use an Orion SSAG. I know from personal experience that the Atlas does a fine job autoguiding at 800mm. I have shot at 2000mm a couple of times and the Atlas did a good job with nice round stars. IMHO, collimation is the biggest 'hurdle' to over come using a newt until you learn how to obtain a good collimation. Your f/4.9 with be a little more forgiving than my f/4.0. Good luck.

-Bill

#35 orlyandico

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Posted 29 April 2011 - 09:28 AM

er. the OP listed the equipment he just bought.. and it includes..

Orion Awesome Autoguider Refractor Telescope Package

#36 EFT

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Posted 29 April 2011 - 10:34 AM

Now I'm wondering what would be the best way to attach my un-forked meade 8" sct OTA to the atlas mount. I need something on the cheaper end as I have already spent more money than my better half allotted me!


For price and quality, the ADM dovetail is really the way to go for your M8.

#37 locod1

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Posted 29 April 2011 - 11:44 AM

Thank you all for the great input. I ordered a autoguider with the atlas mount I haven't been able to use it as of yet because I am still waiting on one more counterweight. After last night I also have a dislike for an EQ mounted Newt, the eyepiece seems to always end up in a totally impossible viewing position. On the other hand for AP it seems to be a dream compared to the LX 50. I used the autoguider package on my LX 50 (as it shipped almost a month before the atlas) and after 3 hours of drift alignment, plus autoguiding I couldn't do more than 25 sec exp. at F6.3. I assume the PE for the LX 50 is just more that can be guide out? Now last night i tryed the new atlas out for the first time, attached is a image I took. I am really excited with this capture, as I only did a quick alignment thru the polar scope. I did not drift or autoguide and this is a 60s exp. M51

#38 Bill W.

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Posted 29 April 2011 - 01:52 PM

er.. orlyandico, it had been a day or two since I had read his original post... :p

locod1... your first image with the Atlas looks good. Congrats!

-Bill

#39 Patrick

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Posted 29 April 2011 - 03:26 PM

er. the OP listed the equipment he just bought.. and it includes..

Orion Awesome Autoguider Refractor Telescope Package



:waytogo:

#40 Bachus

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Posted 30 April 2011 - 09:35 AM

Yep..I agree with others that replacing the OEM saddle with a ADM "Dual Saddle will be your best upgrade you can get and you'll thank yourself.

http://admaccessorie...ual_Saddles.htm

If you check over in the "Imaging" area and search for Guidescope or 50mm there are plenty using this as a guider with say a Meade DSI.Something like this which is what I made..

http://msfastro.net/...der_guidescope/

#41 ADBjester

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Posted 30 April 2011 - 07:36 PM

I was actually wanting to order the "Orion Awesome Autoguider Refractor Package" this weekend. Dont really know how it comparse to other systems in its price range tho.


Reading the older posts in this thread, I noted this one. Since your scope is a Schmidt-Cassegrain, I would advise against any form of piggyback guide scopes.

First of all, both products you mention have simple tube mounts with two tight screws and one loose spring mounted one -- just not stable enough. It will move microscopically in relationship to the imaging scope as the scope moves. (This is one form of differential flexure.) While some have tried with moderate success to use six-point Stellarvue guide rings to minimize this, I've got a KWiq, mounted in rings, with an 8" SCT... and I still had flexure.

Second, the inherent nature of an SCT is that the focusing is done via a mobile primary mirror, which means it's just not rigid enough inside the tube to retain its relative position to the tube (not microscopically, anyway). This is the other form of differential flexure, which simply cannot be overcome with better gear (unless you have a high end SCT with a mirror lock, like the Meade ACF or the Celestron HD lines).

To overcome flexure, you want an off-axis guider. Then, you're using the same light path for the guiding and the imaging -- the OAG can't move relative to the camera, and if you experience "mirror flop", the camera and the guider both see it.

I may throw another reply on after reading other posts, but I've seen some people suggest a CG5. Don't do it. For astrophotography, I saw you comment that you wanted to buy more mount than you need. You also saw the correct advice that (unless you're dealing with a $10,000 Astro-Physics mount), you shouldn't expect to exceed 50% payload for photography. With a 10" SCT in the wings, and likely some additional gear like an off-axis guider ($100 for entry level, up to $700 or more for Cadillacs like the Moag or the Taurus), your camera, your finderscope, dew shield if the dew point calls for it, etc, etc... my guess is that even the Atlas EQ-G or the CGEM may be "pushing" it (if indeed you want to "overbuy".)

Either is a great first mount for AP, but each has their quirks and learning curves and issues to overcome.

If you can stretch your budget into the low $3000 range, though, you absolutely cannot go wrong with the Losmandy G-11. I wish I'd saved up a bit longer and bought that instead of my CGEM.

Jester

#42 ADBjester

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Posted 30 April 2011 - 08:03 PM

Thank you all for the great input. I ordered a autoguider with the atlas mount I haven't been able to use it as of yet because I am still waiting on one more counterweight. After last night I also have a dislike for an EQ mounted Newt, the eyepiece seems to always end up in a totally impossible viewing position. On the other hand for AP it seems to be a dream compared to the LX 50. I used the autoguider package on my LX 50 (as it shipped almost a month before the atlas) and after 3 hours of drift alignment, plus autoguiding I couldn't do more than 25 sec exp. at F6.3. I assume the PE for the LX 50 is just more that can be guide out? Now last night i tryed the new atlas out for the first time, attached is a image I took. I am really excited with this capture, as I only did a quick alignment thru the polar scope. I did not drift or autoguide and this is a 60s exp. M51


That's not a bad 60 second unguided image of M51, especially for your relatively southern latitude.

Take it from someone that just went through all this.... the problem is not in your periodic error. It's probably not even in your polar alignment, though you can bet that if you're doing pure visual drift as a first-timer, you may be making errors. I still can't drift unassisted, and am happy that:

1) The CGEM has a built-in All-Star Polar alignment routine that will get you within one degree of the pole.

2) With a CCD there are ways to "drift" computer-aided, including EQAlign, PHD's companion, PEMPro, and "Straight line exposure".

If you're within a degree of perfect polar alignment, good auto-guiding will overcome the PE of your Atlas easily, for exposures of 5 to 10 minutes. However, if you're experiencing differential flexure (as I detailed in my last post), this can kill your session.

I've also had recent experiences with the mount not being adjusted for backlash (not familiar enough with the Atlas to know where it's settings for that are, but it needs to be done), and having backlash bite you even when adjusted because of balancing issues. You have to have a *slight* imbalance to keep a slight but steady pressure on the gears. If it's told by the guider to slow down or stop, you don't want momentum to carry the scope to the other side of that gear tooth. That motion isn't much -- about 3 small star widths on that mount.... but it will wreck your image.

Since the Right Ascension motion is always to rotate west, to "push back" you'll want a few ounces of "push" toward the East. This differs depending on where the scope is. If the scope tube is on the west side of the mount, move the counterweight more to the east (away from the scope) -- just enough to ensure that that's the ever-so-slightly heavier side. If the scope tube is on the east side of the mount, move the counterweight closer to the scope (again, to the east). Always move the weight toward the east, from perfectly balanced.

I suspect your inability to get beyond 30-60 seconds is either or both of the differential flexure in the standard Orion Easyguide package (mirror flop doesn't matter on your Newt), or a misbalanced scope, or both, and possibly could be to incorrect backlash correction settings as well.

Check all three, and upgrade the mount on your EasyGuide at once. The Stellarvue 50mm rings listed here are cheap (~$20) and far more stable than the spring-loaded junk that shipped with the Orion:

Stellarvue 50 mm finder mount from Skies Unlimited

Good luck!

Jester

#43 locod1

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Posted 01 May 2011 - 08:40 PM

here is a image from the first time I used the auto guider Friday night
M 65 and 66
It is just one exposure of 4 minutes. I adjusted the white balance, but other than that it's just a raw image.






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