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Image taken with New Refractor - what is wrong

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#1 astroricardo

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Posted 06 August 2014 - 08:57 AM

Does this look like a combination of CA or bad collimation or both or what?  First light with a new refractor and I'm thinking it should go back to Orion.  It is that newer EON 110.  What do you guys think?

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Edited by astroricardo, 06 August 2014 - 09:25 AM.


#2 jgraham

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Posted 06 August 2014 - 11:40 AM

Is your T3i modified with a Baader filter or a clear (full spectrum) filter? It looks like your are picking up light beyond the red end of the visible spectrum. An IR cut filter might reduce or eliminate the problem.



#3 fetoma

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Posted 06 August 2014 - 11:49 AM

Looks like a collimation issue to me.



#4 mmalik

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Posted 06 August 2014 - 12:07 PM

If that's full frame, if you are blocking IR, if camera is focused, if there are NO orthogonality issues with the train, then yes it would be the scope. Regards



#5 astroricardo

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Posted 06 August 2014 - 01:01 PM

It's not a full frame, just a section.  My camera is not full spectrum modded and I've used it with a refractor before so I don't think I need to block IR.  Thanks for taking a look.



#6 jgraham

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Posted 06 August 2014 - 01:22 PM

Wow, that suggests that the color correction on the EON rolls over really fast on the red end of the spectrum. With my 6" f/8 achromat it is the blue end that I struggle with.



#7 srosenfraz

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Posted 06 August 2014 - 02:43 PM

It's not a full frame, just a section.  My camera is not full spectrum modded and I've used it with a refractor before so I don't think I need to block IR.  Thanks for taking a look.

I would suggest you post the whole sub (a jpeg of it would be fine, but not reduced in size at all) - not just a section of the frame.  Not knowing whether this is one corner, the center, what other corners may look like, etc. leaves room for a lot of guessing. 



#8 astroricardo

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Posted 06 August 2014 - 03:21 PM

It is too big, even a JPG, but it is all over the frame.  Not fully processed, I didn't see the point of finishing.

 

http://astrob.in/111896/0/



#9 Jerry Lodriguss

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Posted 06 August 2014 - 03:53 PM

It looks like some spherical aberration combined with some mis-alinged lens elements.

 

The red halos could be from the spherical aberration, or it could be that the scope is just not focusing these long red wavelengths that a modified camera would be picking up.

 

Even though it is called an "apo", it's probably not really with just an air-spaced doublet lens.

 

You get what you pay for, and you will have to decide if is reasonable to expect perfect performance in an inexpensive Chinese doublet, but the fact that there is spherical aberration and that the core of the star is not centered is not acceptable in any case.

 

I would send it back.

 

Jerry



#10 jhayes_tucson

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Posted 06 August 2014 - 09:44 PM

That looks like spherochromatism.  This is when spherical aberration varies with wavelength.  The only fix is to use a narrowband color filter or to send it back.  I'd do the later.

John



#11 leviathan

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Posted 07 August 2014 - 01:07 AM

f/6 is too fast for ED glass.



#12 jzeiders

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Posted 07 August 2014 - 01:16 AM

f/6 is too fast for ED glass.

 

Oh I don't know about that, my FSQ 106 is ED and works fine at f/5, even f/3.6 with the reducer.  as does my ED 300mm f/2.8 Nikon. It all depends on the design and which ED glass you use and how you use it. :-) Then again neither of the optical systems I mention are considered "inexpensive".

 

YMMV

 

Jack








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