#1  
Old 20-03-2013, 02:07 PM
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Ryderscope (Rodney)
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Help with my field flatener please

I have had my Meade ED80 F6 APO for about 18 months and have only just managed to find time to exercise its capabilities. I have fitted a Hotech SCA field flatener which has improved the field but I am still getting quite noticeable pin cushion distortion. I have provided a link below to a cropped image of Omega Centauri. The top right hand corner seems to be more noticeable.

http://www.astrobin.com/full/36246/

Is this the best that I can expect from this scope or is there likely to be a bug in my image train somewhere? Any assistance in diagnosing this would be much appreciated.

Technical specifications follow:
- Meade Series 5000 ED890 Ff6 APO
- Canon 60Da
- Astronomik CLS-CCD clip in filter
- Custom white balance
- Hotech SCH Field Flatener
- Synguider Auto Guider
- HEQ5 GEM
- Captured with Backyard EOS
- ISO 800, 60 seconds
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  #2  
Old 21-03-2013, 03:00 PM
gbeal
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It's hard to tell, when I click on your link I only get half an image.
I'd say if all four corners are not OK then check the distance that the chip is from the flattener. If only one or two corners are soft it normally indicates the flattener and camera not in the focuser squarely.
Gary
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Old 21-03-2013, 04:04 PM
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Ryderscope (Rodney)
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Thanks Gary, I did only upload the top half of the imag to try and keep the file size down. It is true that the top corners are the worst so you may be right about it being not square.
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Old 21-03-2013, 06:13 PM
gbeal
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Rodney.
Ah, makes sense then.
If possible screw all the sections together, but that's not always possible I know.
Shimming the flattener so it doesn't "wobble" might help too.
Gary
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Old 22-03-2013, 06:19 AM
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MrB (Simon)
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Does the Meade have a rotateable focuser? These can introduce tilt and some(like my Stellarvue) have screws to adjust the tilt out.
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Old 22-03-2013, 09:12 AM
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Ryderscope (Rodney)
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Quote:
Originally Posted by MrB View Post
Does the Meade have a rotateable focuser? These can introduce tilt and some(like my Stellarvue) have screws to adjust the tilt out.
Thanks Simon, I have never noticed any options for rotating the focuser on the Meade but I will look at this and check. Thanks for your post.
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Old 24-03-2013, 08:38 AM
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PRejto (Peter)
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You might also try CCDInspector (free trial available). It will diagnose all sorts of problems and provide you with 3D maps. I have found that I cannot live without this software. http://www.ccdware.com/products/ccdinspector/

Peter
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