Old 24-07-2011, 10:47 PM
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DavidTrap (David)
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More questions about alignment of my scope

I started a thread here a while ago with questions about collimation of my Tak FS-102.

After much discussion, I found there was significant slop in the focuser when the focus lock knob was left undone (as recommended by Robofocus). It has gotten considerably better since I have been gently screwing that knob down - the wiggle in the focuser has gone.

I took some flats last night as the object went through the meridian - so the scope was pointing vertically.

Here are some screen shots. There is a well illuminated "circle" - but that circle is not centered on the CCD chip. (Should I expect that the chip is in the centre of the opening of the camera - QSI583) I have adjusted the screen stretch to exaccerbate the edge of the circle. The transition on the graph is thankfully more gradual.

I've also attached a curvature analysis from CCD inspector for my image from last night. The "tilt" is in the same direction.

Any suggestions - or do I have to go looking for more slop in my focuser? (I am yet to do the obvious and spin the camera around 180 degrees and see what happens)

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Old 25-07-2011, 11:43 AM
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RickS (Rick)
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I am also having some intermittent tilt and curvature issues with my FSQ. I had hoped they would go away when I got the last couple of adapters needed for a fully screwed together optical train, but alas they haven't. When I figure out what is going on I will let you know. So far my reasonably methodical troubleshooting attempts haven't resulted in a Eureka moment. I'm wondering whether I might actually have more than one problem...

Good luck with your troubleshooting!

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Old 25-07-2011, 07:05 PM
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I'm no expert, but IIRC there are two very very fine screws on the top of the focuser, near the big lock down knob. They may have, some form of sealant on/in them. Tighten them, very carefully and gently. They push down like the big tightening knob.
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Old 25-07-2011, 08:41 PM
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DavidTrap (David)
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You are correct Gary - a guide to adjust them was posted on the previous thread.

Might need to pluck up courage and fiddle with them.

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