Re: [ATM] Ghost image

["Jerry" <wa4guu@verizon.net>]

Mel was right. The second time. It is in the eyepieces.

Astigmatism and pinched optics would for all practical purposes place the
main and "ghost" images in a pretty much fixed relative position to each
other. They would move through the field in formation. Pretty much the same
for my second surface reflection idea also.

In the case of internal reflections in the eyepiece, If the eyepiece were
squared on the optical axis it would be expected that the main and a ghost
images would be superimposed on each other when the object is in the center
of the field. In most cases as the object moves off center the ghost will
separate from the main image and maybe even go the opposite direction.

Either...
Your focuser's axis is not tracking straight on, or is not centered on the
optical axis. It may be off only a small amount, but your alignment is not
perfect. When it is perfect the ghost and main image will be at the center
of the field at the same time, and separate as the object moves off center.

Or...
Your draw tube has slop in the fit to the focuser body allowing it to tilt
out of alignment. You might see that it will tilt one way when you rack in
and tilt the other when you rack out. The tilt effect from the slop might be
exaggerated when the eyepiece focuses close to the full racked out position
as opposed to near full racked in.

Whichever it is the effect is the same. Your eyepiece is tilted or off
center to the telescopes axis. 

Jerry

-----Original Message-----
From: vorblesnak@peak.org
 
The ghost is more of a blob than a out of focus
Saturn as it were, but one could tell it was Saturn that is out of focus.

As the image of Saturn moves across the field of view the blob will come
closer to the infocus image.  If I wander around the eyepiece I can find a
spotwhere the blob is not seen.

I collimated the scope by eye, then by laser. 


David Davis
Toledo, OR 97391






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