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May 2nd H-Alpha

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#1 wargrafix

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Posted 04 May 2021 - 10:35 AM

Trying to diagnose the double limb issue, I focused on what may be incurring the error. Visually when in focus, the double limb can be seen.

 

Adjusting the tilt doesn't seem to have any meaningful change. Either of the etalons, did very little to change the limb issue. I will try without the 2X barlow to see if it is incurring errors. 

 

Here are different limb locations. The "left side is always better in terms of the limb issue.

 

Coronado Solarmax 2 60mm DS

2x barlow

ASI224MC

 

med_gallery_218407_319_158836.jpg

 

 

right side with limb issue  

med_gallery_218407_319_285890.jpg

 

 

med_gallery_218407_319_23128.jpg

 

med_gallery_218407_319_21393.jpg


Edited by wargrafix, 04 May 2021 - 10:47 AM.

  • peterm, MAURITS, hopskipson and 4 others like this

#2 HPaleske

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Posted 04 May 2021 - 12:10 PM

good job!  The results appear sufficiently homogeneous.

 

cs Harald

www.unigraphprom.de



#3 peterm

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Posted 04 May 2021 - 07:09 PM

Well done indeed!



#4 hopskipson

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Posted 04 May 2021 - 07:37 PM

Nice job! I really like the first one with the long chain of filaments ending in a filaprom.



#5 wargrafix

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Posted 05 May 2021 - 06:37 AM

Thank you everyone! I am unsure what is inducing the partial double limb

#6 HPaleske

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Posted 05 May 2021 - 10:40 AM

...

I think

a) that the flanks of the halp line are not steep enough and therefore parisitic photosphere light penetrates. Only the specification of the half value width is not enough. or

b) the half value width is not yet tight enough or
c) Etalone finesse is not good enough

d) The beam path is not slim enough

 

 

cs Harald

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#7 wargrafix

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Posted 05 May 2021 - 12:52 PM

How do I correct for that?

#8 HPaleske

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Posted 05 May 2021 - 01:08 PM

The easiest way is to improve the focal ratio to make the optical path slimmer (d). However, the telecentricity must be maintained. This is not possible with a simple barlow. You need a stronger telecentric for this. However, this leads to a long focal length. The focal length must then be reduced again.

The other three possibilities, a) to c), can only be improved by higher quality etalons.

 

update:

There is one more possibility.  Use three etalons (tristack).
Unfortunately, the brightness then decreases rapidly and the etalons must be aligned exactly.

 

cs Harald

www.unigraphprom.de


Edited by HPaleske, 05 May 2021 - 01:12 PM.


#9 astro rocketeer

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Posted 05 May 2021 - 02:20 PM

looks very nice!



#10 wargrafix

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Posted 05 May 2021 - 04:25 PM

Are you referring to a telecentric barlow?

#11 wargrafix

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Posted 05 May 2021 - 04:27 PM

Also.....Grrrrrrrr. this rainy weather is projected to go on for another week!

#12 hopskipson

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Posted 05 May 2021 - 04:52 PM

Are you referring to a telecentric barlow?

A telecentric is an amplifier that also creates a parallel light path before it enters an etalon such as with a Quark.  Baader makes them to use with Solar Spectrum and DayStar SE, PE, and Ion etalons.



#13 HPaleske

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Posted 05 May 2021 - 04:52 PM

"...Are you referring to a telecentric barlow?"  

 

No, it should be a real telecentric system (example Baader a.o., Unfortunately only quadruple magnification .)

 

cs Harald

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#14 hopskipson

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Posted 05 May 2021 - 05:07 PM

"...Are you referring to a telecentric barlow?"  

 

No, it should be a real telecentric system (example Baader a.o., Unfortunately only quadruple magnification .)

 

cs Harald

www.unigraphprom.de

Hi Harald

 

I'm not sure a telecentric is going to help the OP.  The scope in question is a Solarmax II which use internal and external etalons.  Unless I'm missing something.  I have the Solarmax II also and I can attest that the etalon finesse is not that great.



#15 HPaleske

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Posted 05 May 2021 - 06:05 PM

James,

 

the slimmer the beam path, the easier it is for the etalons to work properly, which means a small aperture ratio.  Of course, there is nothing you can do if the etalons are of poor quality.

 

I use select Lunt 35mm etalons. There are big differences.

 

cs Harald

www.unigraphprom.de


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#16 wargrafix

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Posted 05 May 2021 - 07:05 PM

I use vivitar teleconverters for my planetary work, and they make regular barlows look like a joke.

The 2x requires a bit more infocus distance.

When I get clear skies I need to try my 3x teleconverter

#17 wargrafix

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Posted 06 May 2021 - 02:11 PM

med_gallery_218407_319_808142.jpg

 

med_gallery_218407_319_437800.jpg


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#18 rigel123

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Posted 06 May 2021 - 08:22 PM

Those last two images look fantastic!

Edited by rigel123, 06 May 2021 - 08:23 PM.



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