Quote:
Originally Posted by davewaldo
hmmm... you've got me thinking...
You say a 30sec or 60sec exposure would be good. What f ratio would that be for? I'm assuming one could get a usable image quicker with an f5 scope than one could with an f12 scope?
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Apature is a factor, as is Focal length. Depends on the object.
For example: My 12" dob (f5) will not give nice wider images like my ED80 (f7.5) becuse of focal length. So it isn't as cut and dry as 'focal ratios'. There are some maths involved to solve what focal ratio for what object.
My images above are using the ED80.