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[Africajill]

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!!!
Jill

[TomT]

Jill,
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.

"Focusing
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
counterclockwise.
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."

[brucesbau]

I also have a C11, and sometimes focus is tack sharp, other times, not.

Telescope optics are designed to focus undistorted (plane) light waves (wavefronts) to a point.

The gremlin is atmospheric turbulence.  A typical turbulent cell is about 10 cm in diameter (4").  Light that enters one side of your C11 travels through a different path in the atmosphere than light entering the other side.  The incoming light wavefront is not planer, i.e., it is wrinkly; hence, the light does not get focused to a point.

The larger the scope, the worse atmospheric distortion becomes.

The light from objects directly overhead only has to go through 60 miles of atmosphere.  The light from objects near the horizon has to go through 1000 miles of atmosphere.

The air over the ocean tends to be more stable; hence, clearer images result.  When we go to Refugio Beach State Park for public outreach, oftentimes we get quite good viewing.

Going to higher altitude helps also.

On the plus side, the larger the scope, the brighter the image.

You also want to make sure your scope is well collimated.  On a Schmidt Cassegrain scope, like the C11, collimation is done with tiny adjustments of the three screws in the secondary mirror.  Image a bright star and throw the scope out-of-focus.  You should see the shadow of the secondary mirror in the middle of the disc of the out-of-focus star.  If the shadow is not concentric with the star disc, then collimation is required.

Bruce Murdock

[TomT]

Bruce,
It turned out that it was a collimation problem.  Unfortunately, first I took apart the eyepiece thinking it was the problem, then had to buy a new one since I could not figure out how to reassemble it!  I still need to work on restoring that eyepiece...where did that thing go to?
TT

[brucesbau]

Tom,

What is the eyepiece make and model?

I hope you marked the lenses as to which side faces the telescope (or the astronomer).  Why don't you bring the eyepiece remains to the next telescope workshop.

If you used spanner wrenches to unscrew retaining rings, please bring them also. 

Let me know when you plan on comping, and I will bring a tanks of compressed air and air nozzle to blow out dust, etc., as assembly proceeds.

Bruce

[TomT]

Bruce,
Just noticed your reply...I will email or call you on scheduling a reassembly....Thanks for your interest!
Silly to just have it sitting in front of my face.   Nope, did not mark lenses before I realized I goofed up.