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#1 zoltrix

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Posted 18 September 2021 - 06:22 AM

hello

out of curiosity
suppose you have a refractor 100/500 + barlow 2x and a newton 200 / 1000
you take a picture of a galaxi, same magnification
a longer integration time for the refractor the focal ratio being f10 vs F5
with the refractor you should achieve an higher contrast with the newton an higher resolution
All other things being equal which is better ?

Edited by zoltrix, 18 September 2021 - 06:24 AM.


#2 Avgvstvs

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Posted 18 September 2021 - 07:03 AM

Resolution is determined by the diameter of your objective.

So that would give you resolution rather than contrast.

Contrast is reduced with a secondary mirror, so who can tell?

I guess a lot would depend on the quality of the optical systems,

baffling/EP/sky conditions etc. So I'm not sure you can easily answer this question



#3 Jon Isaacs

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Posted 18 September 2021 - 08:47 AM

Contrast is reduced with a secondary mirror, so who can tell?

 

 

Fine scale contrast is reduced by a secondary obstruction, when compared to an unobstructed scope of equal aperture.   But when one scope has twice the aperture, the smaller scope will have the poorer fine scale contrast.  

 

When imaging galaxies, resolution and fine scale contrast are not the important parameters.

 

Jon


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#4 zoltrix

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Posted 18 September 2021 - 12:53 PM

hello

thanks Jon
what are the most important parameters when imaging galaxies ?


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