Finder orthogonality

[Stonius (Markus)]

I had my new 16" Hubble Optics ultra light out for the first time the other night. I'm pretty happy with the construction, optics and movement, though I have a lot more testing to go.

But there was something strange with alignment of the finderscope (supplied by me) that I have never seen before on any of my other telescopes.

Usually I look through a finder with both eyes open, so I can see the crosshair in one eye, and the object in the sky with the other. Then it's just a simple matter of putting the crosshair over the object in the sky and bam! It pops right into the field of the finderscope.

Where it got weird was that the finder was accurate, in that an object on the crosshair would be centred in the eyepiece, but the old 'use both eyes' when using the finder trick didn't work. Placing the crosshair over the object in the sky was usually off (too high).

So...the finder was aligned with the telescope, but not the sky if that makes sense? I can't figure out what ajustment to make. Maybe the optical axis of the scope needs tweaking to be parallell to the mechanical axis? Thqat's all I can think of.

Markus

[bojan]

This may happen if crosshair is not aligned with optical axis of the finder... maybe ?
Finder magnification may then exaggerate the effect.
Eye fatigue can be the factor as well.
BTW, I am using the same technique for coarse pointing, but always refine with one eye (through finder).

[Stonius (Markus)]

Maybe that's it. I had removed the EP to put new batteries in the reticule illuminator, so maybe I put it back in slightly crooked. Thanks, I'll test this scenario.

Cheers

Markus