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FSQ85 misalignment?


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I got my new FSQ85 sometime ago, and have been struggling with elongated star issue. Basically the star at different corners show different shapes.
 
I did some tests this week without CAA, trying to figure out what the problem is.
 
1. FSQ85 -> 72mm thread extension -> 55.9mm thread adapter -> customized T2 adapter -> 20mm T2 extension -> CCD
 
2. FSQ85 -> 72mm thread extension -> 55.9mm thread adapter -> customized T2 adapter -> 40mm T2 extension -> CCD
 
3. FSQ85 -> 72mm thread extension -> 55.9mm thread adapter -> customized T2 adapter -> 40mm T2 extension -> DSLR
 
From images, clearly there is some tilt. I think #1 and #3 are more severe because tilt is on diagonal direction.
Looks to me that either optical or focuser is not aligned (assuming all threaded adapters are aligned), because tilt on #1 and #3 is same wrt star position. 
#2 is not severe as tilt is more up-down direction if my theory is correct.
 
The focus is done on the brightest star using mask for all images.
 
Has anyone had the similar issue with FSQ85 before? What is the most probable cause?
 
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I find this an odd problem, I have an fsq106 and my subs show some elongation usually in one of the corners, both with a reducer and without.

so...I carried out a number of tests taking short subs...10 secs maybe of a rich star field high altitude without guiding, say 20 subs.

i combined them in CCD inspector  and looked at the result...it looked very flat. I couldn't make sense of it but......if I then take say 20 X 20 min subs and combine them to form an image, I find the the image shows round stars in all corners.

so..as far as my subs go, I just ignore the shape!

baffled but happy

Ray

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1. FSQ85 -> 72mm thread extension -> 55.9mm thread adapter -> customized T2 adapter -> 20mm T2 extension -> CCD
 
2. FSQ85 -> 72mm thread extension -> 55.9mm thread adapter -> customized T2 adapter -> 40mm T2 extension -> CCD
 
3. FSQ85 -> 72mm thread extension -> 55.9mm thread adapter -> customized T2 adapter -> 40mm T2 extension -> DSLR
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5 hours ago, ollypenrice said:

If you don't have the reducer in the system you should just focus and get clean stars. If you don't then the scope has a problem. I've read on here of a couple of bad ones so it can happen.

Olly

Thanks! I have contacted the dealer to analyze my images. Hopefully I will get reply soon.

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1 hour ago, libraryman said:

I find this an odd problem, I have an fsq106 and my subs show some elongation usually in one of the corners, both with a reducer and without.

so...I carried out a number of tests taking short subs...10 secs maybe of a rich star field high altitude without guiding, say 20 subs.

i combined them in CCD inspector  and looked at the result...it looked very flat. I couldn't make sense of it but......if I then take say 20 X 20 min subs and combine them to form an image, I find the the image shows round stars in all corners.

so..as far as my subs go, I just ignore the shape!

baffled but happy

Ray

I just uploaded JPG file, does you image look similar or worse than mine?

I can try to do some long exposure images and stack.

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8 minutes ago, blackdragon72 said:

I just uploaded JPG file, does you image look similar or worse than mine?

I can try to do some long exposure images and stack.

Actually mine has bad star shapes on 3 corners. Eg, 

https://drive.google.com/open?id=0B-QlWQSc_Fi0bXF5ZVFyX0NHb1U

top left looks fine, bottom right is the worst which looks like just regular elongate star, the other two look like field rotation, so looks to me system is tiled from top left to bottom right.

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Just out of interest what is the serial number on your scope? We still have a record of the number for the one that we returned late last year as unusable - see the link that gnomus posted about the problems that we experienced.

I strongly suspect that our duff FSQ85 will have been sold on to someone else but would be a little surprised if it had crossed the Atlantic but perhaps another from the same batch?

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51 minutes ago, MrsGnomus said:

Just out of interest what is the serial number on your scope? We still have a record of the number for the one that we returned late last year as unusable - see the link that gnomus posted about the problems that we experienced.

I strongly suspect that our duff FSQ85 will have been sold on to someone else but would be a little surprised if it had crossed the Atlantic but perhaps another from the same batch?

Your image was far better than mine so it can not be the same one.

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