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Weird arcs on my photos?


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Today I finally picked up my focal reducer, and took it outside and had a blast.  It really has taken my AP to a new level.  However it is not all good, as well as incrediblt detail compared to before I also have some... I am not sure what to call them.  Arcs of light? Flares?

They look similar to the aberations I see due to air currents when the scope is cooling, but these were after 2-3 hours of cooling.  Can anyone advise?  Below is the Orion I took (with a blown out core, that is something separate I need to work on) 

On the right hand side of the image you can see one huge faint arc, and one very bright one coming out of a star.  Is this a flaw to do with focal reducers?

Setup was:

Celestron C8 with 6.3 focal reducer

CG5 mount

Canon EOS 1000d unmodded

7 x 90 second lights

10 darks

5 flats

10 bias.

As always, any other feedback on the images would be much appreciated.

post-36407-0-47567000-1419032407_thumb.j

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Hi

Someone else posted about a similar problem recently:

http://stargazerslounge.com/topic/228829-elliptical-circles-around-bright-stars-in-long-exposure/

It seems to be a bright star problem with Celestron SCTs.

Louise

Edit: Just looking again at your image you may also have a tilt issue (eggy stars on the left) though I confess I know little about SCTs...

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You could try swinging the scope to centre the artefact and shoot a few subs. They might be fine on axis. Then you'll need some processing tricks to use the new ones as a fix but it can be done.

Olly

I have looked at all my subs for the evening.  Basically any brightness on the edge of the field of view(eg windows from a nearby house that aren't in frame but I know were near) have large arcs in the image.

On the plus side I found some time today to spend on youtube and I learned about layer masks, gaussian blur and other such esoteric terms and came up with this:  I am aware that the core is too faint now, but I am quite happy with a first attempt.

16062251042_ae8735ef60_s.jpgOrion Blended by Ryan Simmons, on Flickr

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