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Seriously Thinking of Packing It In :-(

richyrich_one

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richyrich_one

richyrich_one

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I have all but given up trying to get anything half decent from my scope coma corrector camera combination.

After completely redoing collimation, centering the secodary under the focuser, tilting it to get the clips evenly in view and aligning the primary it seems worse than ever! (no lasers were involved btw)

This is an example. What the hell is going on in the bottom left corner?? The rest aren't much better. There is always off centre flaring on the outer edges of all my images. I'm pretty sure it all started to go wrong after flocking. BIG mistake!

I don't want pack it in but I have completely lost the plot as to what could possibly be going wrong and where anymore.

Single__2017-01-02_21-49-52_0002_ISO800_60s__19C.JPG

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D4N

D4N

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Yeh the right side looks like minor coma but the left side is a bit of a disaster.  It looks like the left 1/4 of the image is noticeably darker and the stars are smeared oddly.

Does it stay on the left side of the image if you rotate the camera / corrector in the focuser?  Maybe something isn't square, how is the camera / corrector connected to the scope?

 

I would use this as the perfect excuse to get a small format CCD that will conveniently only see the good bit in the middle :)

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Charic

Charic

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1 minute ago, richyrich_one said:

Seriously?

Yes I was serious, although now sitting in a dark room, lights off,  looking at the screen, there is a slight  difference between left/right image.
I don't do imaging, but I'd still be happy to pin that image up.

BUT DON'T QUIT - HAVE A DRINK -THINK IT THROUGH.

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richyrich_one

richyrich_one

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2 minutes ago, D4N said:

Yeh the right side looks like minor coma but the left side is a bit of a disaster.  It looks like the left 1/4 of the image is noticeably darker and the stars are smeared oddly.

Does it stay on the left side of the image if you rotate the camera / corrector in the focuser?  Maybe something isn't square, how is the camera / corrector connected to the scope?

 

I would use this as the perfect excuse to get a small format CCD that will conveniently only see the good bit in the middle :)

I've packed in for the night now so can't try any rotation experiments.

The camera is connected by the usual method of thumscrews although I have added a third.

I tried some rotation experiments earlier today while testing flats, I got these results.

0 deg

_0_Deg_contourPlot.png

90 deg

_90_Deg_contourPlot.png

180 deg

_180_Deg_contourPlot.png

 

270 deg

_270_Deg_contourPlot.png

 

Then after recollimation I took another at 0 deg, not perfect but much improved I thought.

F_2017_01_02_07_45_47_0001_ISO800___20C_contourPlot.png

So I was feeling pretty confident that all was pretty good and set for a decent night of imaging.

But the results were worse than ever.

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RayD

RayD

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Yes it's not ideal is it. Not sure what to suggest to correct but I do feel your pain and can only urge you to look again at alignment as that seems to be the issue.

above all don't quit as the rest of the image is great.

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richyrich_one

richyrich_one

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6 minutes ago, Charic said:

Yes I was serious, although now sitting in a dark room, lights off,  looking at the screen, there is a slight  difference between left/right image.
I don't do imaging, but I'd still be happy to pin that image up.

BUT DON'T QUIT - HAVE A DRINK -THINK IT THROUGH.

 

I don't normally drink but I'm thinking of taking it up!

It's just mystifying. I am obviously doing something wrong, screwed something up, just wish I knew what.

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Peter Drew

Peter Drew

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6 minutes ago, richyrich_one said:

That was one of the things I did, loosened the primary clips just to make sure it wasn't being pinched.

That's good. Did you also check whether the mirror rotated easily, I've often found that despite loosening the clips the mirror was still stuck if it had been overtightened initially.  :icon_biggrin:

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richyrich_one

richyrich_one

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6 minutes ago, Peter Drew said:

That's good. Did you also check whether the mirror rotated easily, I've often found that despite loosening the clips the mirror was still stuck if it had been overtightened initially.  :icon_biggrin:

Yes it could rotate freely.

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Peter Drew

Peter Drew

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2 minutes ago, richyrich_one said:

Yes it could rotate freely.

Sorry to have laboured that point Rich, it's just that I see a suggestion of deformation in the rotation images which could easily have been the result of pinched optics.  :icon_biggrin:

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richyrich_one

richyrich_one

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3 minutes ago, Peter Drew said:

Sorry to have laboured that point Rich, it's just that I see a suggestion of deformation in the rotation images which could easily have been the result of pinched optics.  :icon_biggrin:

No problem, any suggestion is greatly appreciated.

As you say there appears to be distortion. That's got me worried, what else could cause it if not the optics?

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Chris

Chris

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I bought a second hand f/4 imaging newt once where someone had previously silicone sealed the primary in place. All I can say is my word were the stars weird! some approaching figure of eight shaped! I didn't know what was causing it at the time so sold it very cheap with full disclosure. The guy that bought it freed the primary which fixed the problem in 30 minutes!... you live and learn hey!

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richyrich_one

richyrich_one

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I guess the first step is to attach the camera assembly to my other scope and see what I get.

I hope I haven't mullered the primary somehow. It's possible its been tight, although not overly, for quite some time and now that I have released the pressure it's all over the place.

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richyrich_one

richyrich_one

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Just educated myself on primary mirror clips...wow never would have believed it. It's possible I need to back off the clips even more. I will recheck that they are indeed loose and not actually holding the mirror at all.

Meanwhile I am taking subs with the 250 and all looks pretty good so at least I have (with your help) narrowed the problem to the scope and most likely the primary mirror. I think that's good news :undecided:

I just hope no permanent damage has been done.

Thanks everyone for listening and giving suggestions, without this forum it would be a whole lot harder. :icon_biggrin:

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Chris

Chris

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3 hours ago, richyrich_one said:

 

I just hope no permanent damage has been done.

 

I doubt there would be, I've seen pinched optics with both lenses and mirrors, and once loosened they are generally fine :) 

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RayD

RayD

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5 minutes ago, moonomaly said:

Speaking as someone who hasn't taken an astrophotograph yet, the image in the OP is stunning and i can't see a thing wrong with it!

 

 

Best, Gary.

 

That's what I said, most of the image is great, but if you look at full scale and then look bottom left you will see the stars go fuzzy and elongated, so I can definitely see Rich's frustration.

This will get fixed, it always does, then we all want to see the image with the issue fixed :thumbright:

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Charic

Charic

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14 minutes ago, moonomaly said:

Speaking as someone who hasn't taken an astrophotograph yet, the image in the OP is stunning and i can't see a thing wrong with it!

 

 

Best, Gary.

 

Seriously is what I got? Lol. but I was of the same opinion, yet enlarged,  in a darkened room, magnified, I think one of the pixels could have been modified a little bit more ? 

What do we know! Lol

 

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richyrich_one

richyrich_one

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16 minutes ago, moonomaly said:

Speaking as someone who hasn't taken an astrophotograph yet, the image in the OP is stunning and i can't see a thing wrong with it!

 

 

Best, Gary.

 

 

2 minutes ago, Charic said:

Seriously is what I got? Lol. but I was of the same opinion, yet enlarged,  in a darkened room, magnified, I think one of the pixels could have been modified a little bit more ? Lol

 

All I can say is you'd be blown away by the stuff I'm happy with :icon_biggrin:

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