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Old 20-06-2015, 07:22 AM
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PRejto (Peter)
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Join Date: Jan 2011
Location: Sydney, Australia
Posts: 1,299
Thanks for posting this! I learned a lot by listening to the whole seminar.

Of course, I immediately compared my puny effort to theirs and was intrigued by the formulas for calculating the apeture and effective fl of multi telescope systems:

A = V n x size

fl = individual fl/ V n

n = number of lenses

V = square root (how do you get this sybol on an iPad?)

I'm wondering if anyone knows the formula for A (aperture) for combining lenses of different size (in my case 140 and 180 mm)?

I took the average of using 2 140 mm + 2 180 mm lenses and got 225mm. Not sure if that would be correct. Since both scopes are f7 I think my system is equivalent to f4.95.

Thanks,

Peter
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