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Collimation of SCT; Edge HD

astrophotography beginner cassegrain Celestron
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4 replies to this topic

#1 kuschivonhausen

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Posted 15 October 2019 - 02:51 PM

Hello,

 

my attempt at collimating my SCT. Magnification is approx. 500 x. Is it possible to achieve good collimation with this seeing or is it hopeless.

https://www.youtube....h?v=1mZoJ-fzu1Q

 

Thanks for your answers.


Edited by kuschivonhausen, 15 October 2019 - 03:01 PM.


#2 freddie

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Posted 15 October 2019 - 03:25 PM

MetaGuide would help a bit but good seeing is preferred.



#3 Kokatha man

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Posted 15 October 2019 - 06:39 PM

Hi k/h - Metaguide is a good program for people who aren't confident of their ability to visually appraise de-focused star patterns & especially so for poorer seeing conditions. (mind you, I have no personal experience using Metaguide but am sufficiently confident of the author's (Frank) & users' integrity/experiences to affirm the preceding!)

 

I am strictly a visual exponent of what I do admit is a skill won by hard work & experience - you can find a few notes at the start of my processing tutes on our website & of course our hi-res images should attest to our capabilities overall: https://momilika.net...rocessing.htm      

 

NOTE: remove the suffix %C2%A0%C2%A0 that CN seems to randomly apply to the url of many links & the proper link should appear - if you have further problems just use the website link in my signature & find your way to the processing tutorials..! wink.gif

 

The examples were with the ASI224MC camera & a C14 so they a good comparative examples - I do not know if your youtube image is magnified beyond what the camera recorded but there are a few things that are instantly recognisable to the trained eye...the central "Poisson Point" is inclined towards the 4/4:30 clock position with a subsequent brightening of the outer rings displayed between 3 & 6 o'clock...also there is very little indication of any illumination of the inner rings between the PP & that outer band - which comprises only a faint one inside a much brighter outer ring that has that brighter portion between 3 & 6.

 

There is a faint indication of a first diffraction ring around the PP where the inclination towards 4/4:30 is amplified in comparison to the nearness of that outer ring: this is to be expected & confirms this.

 

Without repeating all that I say in the link on our website wink.gif I recommend that you go there & look at the realtime, real animations & read it carefully!

 

Good seeing makes collimating much easier & it is an art to collimate accurately in poorer seeing conditions - if this appears too challenging then I'd suggest Metaguide will be your friend! smile.gif


Edited by Kokatha man, 15 October 2019 - 06:42 PM.

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#4 RedLionNJ

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Posted 16 October 2019 - 06:29 AM

I wouldn't consider seeing like that to be at all helpful in collimation - it's just too challenging to judge.

 

It's not totally clear to me if this is "seeing" or the result of a non-equilibrated optical system. But the effect is the same.  Make sure to let any reasonable-sized SCT cool for a couple hours before trying precise collimation.


Edited by RedLionNJ, 16 October 2019 - 06:29 AM.


#5 kuschivonhausen

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Posted 19 October 2019 - 07:57 AM

Freddie, Kokatha and RLNJ,

 

thank you for your valuable recommendations. That is more advice than I could have hoped for. I will try all of those things when the sky is clear again. Maybe the seeing will be better then.

 

Thanks again

 

Regards

vonhausen




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