Pinched optics, backspacing error....or both?

Acquisition Deep Sky Troubleshooting Collimation
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Piers Palmer avatar
Piers Palmer avatar
I managed about two hours of imaging last night with my R200SS and have very quickly processed the images this morning; 40 x 180" frames.  

I've been using the scope for years now, so have the backspacing sussed (I think) and collimation is ok (I think) but this image is weird. The top left looks ok to me, but the other three corners are horrid. Have I got a pinched mirror? 






I did deconstruct the cell recently after a slight accident with primary, but I wonder if something's a bit too tight after putting it all back together.  The odd thing is, I took this image the other night with exactly the same set-up and didn't have this problem. 

Can anyone help?
Engaging
Piers Palmer avatar
Piers Palmer avatar
Blurxtermintor seems to sort it out, but I'd prefer it didn't have to!
andrea tasselli avatar
andrea tasselli avatar
I guess it's tilt more than anything. And you used  BXT on the other one so it's hard to compare, isn't it?
Piers Palmer avatar
Piers Palmer avatar
I didn't think I had initially, but yes, I had., so good point. 

So where do I begin with tilt? Could it be caused by the secondary? The camera and spacers combo is the same as I use on my refractors which report almost zero tilt, so it's something unique to the Newt.
andrea tasselli avatar
andrea tasselli avatar
Could be tilt in the primary so my first port of call would be to check collimation to death. All the times I get something like that it is because, reasons unkown, the collimation screwed up one night to the next.
Piers Palmer avatar
Piers Palmer avatar
I think my first port of call might be my 115mm apo!
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