Telescope Reviews: AT6RC - Use Of Extensions

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Equipment Discussions >> Cats & Casses

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theflop
super member

Reged: 02/25/09

Loc: Ortonville, MI

AT6RC - Use Of Extensions
#4509099 - 04/10/11 01:13 PM

Here is my situation:
When I set up my Celestron ASGT and AT6RC I use only the 2" extension so I may achieve focus with my eyepieces. I align my mount using the 2-star and polar alignment routines. I use Orion eyepieces and an illuminated eyepiece with crosshairs. To proceed to imaging with my Canon 300D DSLR I have to remove the focuser, add the 1" extension then put the focuser back on (3" of total of extensions). I can then focus the camera.
I was just wondering if everybody goes thru this procedure every time they image (non-permanent setup). It's alot of unscrewing and screwing of focusers and extensions every time. Seems like I am doing extra work but I know of no other way. I also don't like fiddling with my scope after I achieve alignment in the dark.
What procedures do you guys perform? Is there a better way? Can I use some kind of 1" extension on my camera T-adapter instead and forgo using the 1" AT6RC extension all together?

Photos please!

Just an inquiry!

Michael C.
Ortonville, MI

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Falcon-
Post Laureate

Reged: 09/11/09

Loc: Gambier Island, BC, Canada

Re: AT6RC - Use Of Extensions new

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[Re: theflop]
#4509191 - 04/10/11 01:58 PM

The before-focuser extension is a larger diameter then any extensions you could use that go after the focuser. After-focuser extensions may produce vignetting that would not be present otherwise.

For my own AT6RC I use the camera itself connected to a computer to do alignment, using either continuous 1s exposures with the 350d or LiveView video with the 1000D. That may be harder to do with a 300D given it is harder to find software that supports the older camera.

I have read reports that the AT2FF field flattener will let you achieve focus with only the 2" extension in, so that may be a solution if you plan to get the field flattener.

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bluedandelion
Carpal Tunnel

Reged: 08/17/07

Loc: Hazy Hollow, Western WA

Re: AT6RC - Use Of Extensions new

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[Re: Falcon-]
#4509219 - 04/10/11 02:15 PM

Quote:

The before-focuser extension is a larger diameter then any extensions you could use that go after the focuser. After-focuser extensions may produce vignetting that would not be present otherwise.

For my own AT6RC I use the camera itself connected to a computer to do alignment, using either continuous 1s exposures with the 350d or LiveView video with the 1000D. That may be harder to do with a 300D given it is harder to find software that supports the older camera.

I have read reports that the AT2FF field flattener will let you achieve focus with only the 2" extension in, so that may be a solution if you plan to get the field flattener.

I use a 350D which also does not have liveview. My solution was to align my finderscope so that if a star is on the cross hair of the finder, it is centered in the view finder of my camera. Then I use the finder to do my alignment.

Ajay

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darkman
Man In Black

Reged: 10/19/10

Loc: San Antonio, TX

Re: AT6RC - Use Of Extensions new

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[Re: theflop]
#4509220 - 04/10/11 02:16 PM Attachment (30 downloads)

Here’s mine:

1 two-inch extension, Astro-Tech 2” prime focus adapter (Product #: ATPFA), T-ring, and Canon T3.

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Ranger Tim
professor emeritus

Reged: 03/25/08

Loc: SE Idaho, USA

Re: AT6RC - Use Of Extensions new

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[Re: darkman]
#4509264 - 04/10/11 02:44 PM

The AT2FF will work on the Canon Rebels with only the 2 inch ring in place. To align the mount and do drift alignment with an eyepiece I use a diagonal with the eyepiece and it works fine. If I did not have the field flattener I would use my 80mm guide scope to fine tune alignment. It is easier to focus the guide camera rather than dismount, align, remount then refocus the main camera. The prime focus adapter shown above should work well also.

The 6X30 finder I have mounted will get me in the ball park for finding stars, but then the go-to can assume the role of finder.

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darkman
Man In Black

Reged: 10/19/10

Loc: San Antonio, TX

Re: AT6RC - Use Of Extensions new

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[Re: darkman]
#4509281 - 04/10/11 02:54 PM

My other trick is that I’ve aligned the ST80 and the AT6RC dead-on, so I actually just use PHD with the ‘bulls eye’ turned on, and literally use that display for my three-star alignment.

On my last alignment star, I use the Batinov mask and focus up the camera, lock down and head for my target.

My 400D doesn’t have live view, so I use Backyard EOS focus/frame screen and just shoot multiple subs while I tweak the focus.

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Don Trinko
Carpal Tunnel

Reged: 07/05/09

Loc: Ohio

Re: AT6RC - Use Of Extensions new

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[Re: darkman]
#4509395 - 04/10/11 04:11 PM

For my AT6RC I use the 1" extension, a Vixon flip mirror, and the camera hooked directly to the T threads on the flip mirror with the Canon T adapter. Camera and eyepiece both focus almost identical. Don T.

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RAKing
Postmaster

Reged: 12/28/07

Loc: West of the D.C. Nebula

Re: AT6RC - Use Of Extensions new

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[Re: theflop]
#4509454 - 04/10/11 04:44 PM

I feel your pain. With my arthritis, I cannot be screwing and unscrewing things in the dark. Plus, that stock focuser has a bad tendency to cross-thread easily.

For imaging, I use the 2 inch extension, along with the AT2FF with my Canon 40D and it focuses fine.

You could use some Baader T2 extensions to push the camera back the required distance, but that could cause some vignetting as mentioned earlier.

If you don't want to go this route, I suggest you get a decent finder scope (SV, Baader Vario, etc.) and use that for your alignment - skip the eyepieces and go right into imaging.

Cheers,

Ron

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theflop
super member

Reged: 02/25/09

Loc: Ortonville, MI

Re: AT6RC - Use Of Extensions new

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[Re: RAKing]
#4509487 - 04/10/11 04:59 PM

I love these forums!
These are all excellent and helpful replies. I now have MANY more options than I did when I woke up this morning! I never thought of using my guidescope (ST80) for alignment and leaving the AT6RC just for imaging. Maybe I should replace the ST80 (400mm) with my Orion 120ST (600mm) as my guidescope and alignment scope.
Getting a tad off-topic, but who thinks my ASGT can carry the load of the AT6RC and Orion 120ST on the mount together? That would solve my "Use Of Extensions" issue all together...

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imjeffp
Aluminum Falcon

Reged: 09/30/03

Loc: Cedar Park, Texas

Re: AT6RC - Use Of Extensions new

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[Re: theflop]
#4509871 - 04/10/11 08:54 PM

Quote:

I have read reports that the AT2FF field flattener will let you achieve focus with only the 2" extension in ...

That is my setup, and works great.

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RAKing
Postmaster

Reged: 12/28/07

Loc: West of the D.C. Nebula

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[Re: theflop]
#4511711 - 04/11/11 05:30 PM

Quote:

Getting a tad off-topic, but who thinks my ASGT can carry the load of the AT6RC and Orion 120ST on the mount together? That would solve my "Use Of Extensions" issue all together...

You're pushing your CG-5 a bit, but it is something I would definitely try. You might need larger rings, but it's worth the gamble to me.

Ron

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JoseBorrero
Carpal Tunnel

Reged: 09/04/09

Loc: MI

Re: AT6RC - Use Of Extensions new

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[Re: RAKing]
#4544826 - 04/26/11 07:58 AM

I'm wondering when Astronomics will ship my extension rings, I'm still waiting patiently my order since march.

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frebie
Chief assistant to the assistant chief

Reged: 04/29/08

Loc: Neither here nor there.

Re: AT6RC - Use Of Extensions new

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[Re: JoseBorrero]
#4545511 - 04/26/11 01:16 PM

We'd love to ship your 2" extension ring order, along with the extension ring orders of other customers (some of whom have been waiting patiently since February). Unfortunately, we can't ship to you until the manufacturer ships to us, so we also continue to wait patiently.

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JoseBorrero
Carpal Tunnel

Reged: 09/04/09

Loc: MI

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[Re: frebie]
#4545943 - 04/26/11 04:31 PM

I'm sure a machinist at this moment will make a substantial amount of money just for make them ready at least for the next month.

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JoseBorrero
Carpal Tunnel

Reged: 09/04/09

Loc: MI

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[Re: JoseBorrero]
#4547829 - 04/27/11 02:06 PM

Hey, forget this waiting pain. Theres a store in Canada that has them in stock www.qwtelescope.com I called them today and made my order rightway by phone. $39 for 2" and 29 for 1". They are sold under GSO extension rings, remember GSO,Orion,Altar astro are all the same. This scopes 6" and 8" use same rings. Hurry up they're not much left.

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tjay
Carpal Tunnel

Reged: 02/03/07

Loc: just outside of Toronto

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[Re: JoseBorrero]
#4548369 - 04/27/11 07:14 PM

Quote:

Hey, forget this waiting pain. Theres a store in Canada that has them in stock www.qwtelescope.com I called them today and made my order rightway by phone. $39 for 2" and 29 for 1". They are sold under GSO extension rings, remember GSO,Orion,Altar astro are all the same. This scopes 6" and 8" use same rings. Hurry up they're not much left.

I think it's actually www.kwtelescope.com Great people to deal with BTW.

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JoseBorrero
Carpal Tunnel

Reged: 09/04/09

Loc: MI

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[Re: tjay]
#4548761 - 04/27/11 11:28 PM

Oh yeah, thanks

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JoseBorrero
Carpal Tunnel

Reged: 09/04/09

Loc: MI

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[Re: JoseBorrero]
#4557046 - 05/02/11 12:19 PM

Finally, My extension rings arrive just 3 days after ordering.

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hpcdan
journeyman

Reged: 08/15/11

Loc: Iowa City, IA

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[Re: JoseBorrero]
#5263850 - 06/09/12 06:48 PM

Anyone know of a current source for these? I am looking for the 2" version

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