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Author Topic: Trouble focusing sky objects on celestron c11  (Read 585 times)


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Trouble focusing sky objects on celestron c11
« on: March 30, 2017, 12:37:08 AM »

Hi, I am really worried that I may have a very expensive hunk of scrap iron in my backyard right now! Basically, after a few months in storage (in the house) and a move across town, I set up my c11 tonight only to discover that while I could focus on my neighbor's window sharply enough to see the spider inside a web, I could not focus on anything in the sky. Not the sun (with my solar reflector on obviously), nor the moon, much less see any stars at all. The sun and moon I could tell I was centered on from the bright light through the eyepiece, but just couldn't focus any detail. And couldn't see any stars. The eyepiece I have is the celestron luminos. I might add that focusing on the neighbors window, I had to fiddle with the three knobs on the ota that are on the end with the eyepiece. But no matter how much I fiddled with them and the eyepiece together, I just could not see anything further. Not even the distant mountaintop. Where do you think my problem lies, where should I start?! The mirror and glass, etc all 'look' pristine, and the entire telescope has been stored securely in its original packaging all this time. I'd appreciate any advice!!!


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Re: Trouble focusing sky objects on celestron c11
« Reply #1 on: April 02, 2017, 05:30:05 PM »

I heard Jerry, SBAU President, had sent you a reply already on this, but here and attached are some Celestron info in case his recommendations on eyepiece placement distance did not work (you are using a diagonal with the eyepiece, correct?).
Chuck McPartlin and I tried to help you set up your scope at his driveway, a while back.

If you still need help, please feel free to email me at tomcez @ gmail.com or call at 562-8795. Tom Totton

From the Celestron EdgeHD Series manual for OTA's (see attached file) this is the part about focusing and locking the clutches, so read it carefully.

Your telescope's focusing mechanism controls the primary mirror which is mounted on a ring
that slides back and forth on the primary baffle tube. The focusing knob, which moves the
primary mirror, is on the rear cell of the telescope just below the star diagonal and eyepiece.
Turn the focusing knob until the image is sharp. If the knob will not turn, it has reached the
end of its travel on the focusing mechanism. Turn the knob in the opposite direction until the
image is sharp. Once an image is in focus, turn the knob clockwise to focus on a closer object
and counterclockwise for a more distant object. A single turn of the focusing knob moves the
primary mirror only slightly. Therefore, it will take many turns (about 30) to go from close
focus to infinity.
For astronomical viewing, out of focus star images are very diffuse, making them difficult to
see. If you turn the focus knob too quickly, you can go right through focus without seeing the
image. To avoid this problem, your first astronomical target should be a bright object (like
the Moon or a planet) so that the image is visible even when out of focus. Critical focusing is
best accomplished when the focusing knob is turned in such a manner that the mirror moves
against the pull of gravity. In doing so, any mirror shift is minimized. For astronomical
observing, both visually and photographically, this is done by turning the focus knob
Mirror Support Clutches
The EdgeHD Optical tube is equipped with mirror tension
clutches to help support and minimize lateral movement of
the primary mirror during astrophotography.
To use the mirror clutches:
1. Use the focus knob to adjust the primary mirror
to the desired focus.
2. Once in focus, turn the two mirror lock knobs
clockwise until both are very tight and can be
turned no further.
Warning! Once the mirror is locked down, do not turn
the focuser knob without loosening the mirror locks first
Although turning the focus knob should not damage the
telescope, undue stress can be placed on the focus mechanisms causing excessive image shift while focusing."
« Last Edit: April 02, 2017, 10:24:14 PM by TomT »
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