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Refractor collimation question

Equipment Collimation Tilt
4 replies•111 views
Sean Mc avatar
Sean Mc avatar
When i defocus, the center of the defocused stars are all shifted in the same direction across the field. If the primary cell was out of collimation, would the center of defocused stars be radially off center around the field? 

Or is this tilt?  The primary cell does have collimation and locking screws. My camera/filter wheel do not have tilt, as they work just fine on my other two scopes. 

thx in advance!
ScottF avatar
ScottF avatar
If the two circles are not concentric, with the center one off-center, then collimation is off.
Well Written
andrea tasselli avatar
andrea tasselli avatar
It's tilt.
Tony Gondola avatar
Tony Gondola avatar
If you can put an ocular on your scope you'll be able to check this visually and eliminate the camera as a cause. If you still see off-center donuts when out of focus, it's collimation. Also, if your camera had significant tilt it's likely to show up with all your scopes. I vote collimation.
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Sean Mc avatar
Sean Mc avatar
The direction of the “tilt” or “miscollimation” rotates around as I rotate the camera. It has to be somewhere upstream of the filter wheel. 

There is no play in the focuser, and the stars don’t change when I tighten or loosen the lock screw on the rotator. 

I have not really used this scope before, but I did whack it on a wall corner when bringing it up from the basement lol. Stupid crazy german shepherd is to blame for that.