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 Explore Scientific Comet Hunter cannot focus Canon 5D 
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Joined: Thu Apr 26, 2012 12:13 pm
Posts: 6
Post Explore Scientific Comet Hunter cannot focus Canon 5D
I recently purchased the Explore Scientific David H Levy Comet Hunter scope, and have taken it out for a quick view of just the moon since it is the only thing I can see in the sky where I live. With the provided eyepiece, the moon looks gorgeous. Sadly, when I attach my Canon 5D to the scope using a T-ring, there is not enough inward travel on the focusing tube to get a focused image on the camera. Bummer. If I remove the T-ring from the camera and manually hold the camera body to the focusing tube, I can achieve an almost focused image. It is still soft though. This would also make it very hard to do longer exposures when I take it to a dark sky location. Not that I would seriously try that.

I have googled this issue, and it seems to be common with a Newt style reflector. This scope is a MakNewt, so I'm guessing I'm suffering with the same issue. I have read that the primary mirror can be moved, but this seems like the nuclear option to me as that logically means that focus would change for normal viewing.

Does anyone have any suggestions on getting my camera to be able to focus? I'm not ready to buy a dedicated camera, yet.

--
Dylan


Sat Jun 02, 2012 8:16 pm
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Joined: Mon Feb 01, 2010 2:33 pm
Posts: 278
Location: Victoria, Canada
Post Re: Explore Scientific Comet Hunter cannot focus Canon 5D
Are you using the 1 -1/4" adapter or the 2" adapter? You might find that is the difference that you need. Otherwise, I would suggest you contact the vendor.
An aside, unless you have a good mount for this telescope, you will find it very frustrating for visual use and impossible for photographic use. I have been there. And don't expect to take any star photos with this.


Sun Jun 03, 2012 2:05 pm
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Joined: Thu Apr 26, 2012 12:13 pm
Posts: 6
Post Re: Explore Scientific Comet Hunter cannot focus Canon 5D
RogerBotting wrote:
Are you using the 1 -1/4" adapter or the 2" adapter? You might find that is the difference that you need. Otherwise, I would suggest you contact the vendor.
An aside, unless you have a good mount for this telescope, you will find it very frustrating for visual use and impossible for photographic use. I have been there. And don't expect to take any star photos with this.


I am using a 2" t-ring adapter. From further inspection, it is the distance matching the thickness of the t-ring that is required to move the camera's focal plane into the correct position. I have reached out to my local store to inquire about this as well.

As far as the mount goes, I'm using the Celestron CGEM. If that doesn't provide a stable enough system, then I'm quitting this hobby now ;-)


Mon Jun 04, 2012 9:23 am
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Joined: Thu Apr 26, 2012 12:13 pm
Posts: 6
Post Re: Explore Scientific Comet Hunter cannot focus Canon 5D
I wanted to post a follow up with what I was able to do to get this setup to allow me to focus. I contacted the vendor that I purchased the scope from, and they contacted the manufacture. The focus tube on this scope is built with threaded extension tubes, and by default comes with a tube that is set up for eye pieces. The manufacture told us that all we had to do was unscrew the outer ring with the compression ring, then unscrew the extension tube from the scope, and then screw the compression ring back to the scope. That sounds like it might be obvious, except we couldn't get the compression ring to unscrew from the extension tube. After a second call to the manufacture, they told us that they used Loctite on the threads. All I had to do was soak the piece in Acetone for a few seconds to loosen up the glue. After that, I just cleaned up the rest of the glue, and now everything works great.

I just didn't want to leave an old trail on the internet without a solution.


Mon Aug 13, 2012 2:16 pm
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Joined: Tue Jan 29, 2013 1:29 pm
Posts: 1
Post Re: Explore Scientific Comet Hunter cannot focus Canon 5D
and wow, am i glad you did tie up the loose ends, as i was having the exact same problem with a comet hunter i bought used last week. i did the thing with the acetone, the parts came apart, and i was able to screw the compression ring holder to the eyepiece tube and use the 1.25 in nosepiece to hold the camera in place and focus on something several hundred yards away that i previously could not focus on. i ordered a zero profile 2 in to t ring adaptor from orion. thanks for posting this.


Tue Jan 29, 2013 1:36 pm
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