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Need Help about size and Focal Length.

Started by jimw3470, 12/04/2006 10:24AM
Posted 12/04/2006 10:24AM Opening Post
I have a C8 SCT with a focla length of 2000, My 7mm ep is too powerfull for it, moon is OK but overall a 12mm is about as strong as I can enjoy a view with. I figure at 12mm the magnafication is at 166. I want to move up I thought to a 10 inch and thought about a newt based on price and so on, but in looking I noticed that the FL on this is about 1000, which is half of my C8 yet it's a bigger scope. Now I'm confused. I think my 7MM will work better in the 10 inch but mag will only be 142 which is less than a 12mm in my C8. What am I missing??? Thanks Jim
Posted 12/04/2006 10:39AM #1
Jim,

To start with, I think this is just the kind of question that the people up in the "equipment" or "Beginner's" Forums would just love to discuss. These people in this Forum mostly talk about how Astromart itself works (or, rarely, does not work). So, try reposting in the Equipment or Beginner's Forums. You will get a better response.

But, to answer your question. SCT's are famous for having long focal lengths folded into a short tube. A newt, on the other hand, has a longer tube with a relatively short focal length. The length of the tube is related to the length of the optical path in Newt's and Refractors (not exactly, because of dew shields, maybe diagonals, and so forth) but not in an SCT, which folds the light path.

So, don't be surpised.

Alex
Posted 12/04/2006 12:35PM #2
jim wolfe said:

I have a C8 SCT with a focla length of 2000, My 7mm ep is too powerfull for it, moon is OK but overall a 12mm is about as strong as I can enjoy a view with. I figure at 12mm the magnafication is at 166. I want to move up I thought to a 10 inch and thought about a newt based on price and so on, but in looking I noticed that the FL on this is about 1000, which is half of my C8 yet it's a bigger scope. Now I'm confused. I think my 7MM will work better in the 10 inch but mag will only be 142 which is less than a 12mm in my C8. What am I missing??? Thanks Jim
reposted in beginners,thanks