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Andromeda Galaxy
- Conor
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18 years 9 months ago #24447
by Conor
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Replied by Conor on topic Re: Andromeda Galaxy
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- michaeloconnell
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18 years 9 months ago #24449
by michaeloconnell
Replied by michaeloconnell on topic Re: Andromeda Galaxy
Agreed.The bigger the scope for a given F ratio the smaller the field of view.
Jed.
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- markdj
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18 years 9 months ago #24459
by markdj
Mark Stronge
www.stronge.org.uk
google.com/+MarkStronge
Replied by markdj on topic Re: Andromeda Galaxy
Sorry for the confusion Eirik but there have been great images from 80mm scopes, aka Pete Lawrance.
I have seen m51 and it's satellite in 10x50 binoculars so anything is possible. Of course I did not see any detail, just a couple of smudges. As has been already said, a big aperture scope with a fast f/ratio of f/4 will allow you to see the spiral arms of m51. For galaxies, you need absolutely perfect conditions to see anything jaw dropping, star clusters on the other hand are more within your grasp.
I have seen m51 and it's satellite in 10x50 binoculars so anything is possible. Of course I did not see any detail, just a couple of smudges. As has been already said, a big aperture scope with a fast f/ratio of f/4 will allow you to see the spiral arms of m51. For galaxies, you need absolutely perfect conditions to see anything jaw dropping, star clusters on the other hand are more within your grasp.
Mark Stronge
www.stronge.org.uk
google.com/+MarkStronge
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- JohnMurphy
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- Super Giant
18 years 9 months ago #24536
by JohnMurphy
Clear Skies,
John Murphy
Irish Astronomical Society
Check out My Photos
Replied by JohnMurphy on topic Re: Andromeda Galaxy
Sorry to keep the FOV story going.
Maximum FOV of a scope formula is:
(Field stop(mm) x 180/pi) / Focal length
The two variables here are field stop (either 1.25" or 2" usually) and the length.
This however is the maximum FOV possible. You really need to bring the eyepiece to bear.
True FOV at an eyepiece is:
apparent FOV of the eyepiece / magnification
magnification is calculated by:
Focal length of scope / focal length of eyepiece.
Therefore it should be apparent that the eyepiece is a tad more important here. The shorter the focal length of the eyepiece, the smaller the true FOV.
Maximum FOV of a scope formula is:
(Field stop(mm) x 180/pi) / Focal length
The two variables here are field stop (either 1.25" or 2" usually) and the length.
This however is the maximum FOV possible. You really need to bring the eyepiece to bear.
True FOV at an eyepiece is:
apparent FOV of the eyepiece / magnification
magnification is calculated by:
Focal length of scope / focal length of eyepiece.
Therefore it should be apparent that the eyepiece is a tad more important here. The shorter the focal length of the eyepiece, the smaller the true FOV.
Clear Skies,
John Murphy
Irish Astronomical Society
Check out My Photos
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