hi matt,
you have a 200mm aperture (8") f5, so i would calculate your focal length to be 1000mm ie 200 x 5
if you start using a 2x barlow, that now is 2000mm or the ratio that was f5 (1000/200) is now (2000/200) = f10
a 5x powermate would give you 5000mm focal length of ratio of f25.
hope this helps
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Originally Posted by matt
Bert
Great pic. I'm new to imaging. Can you explain how you achieve F/32?
I keep seeing people refering to the effective f number of their scope for a pic, but don't know how they achieve it or calculate it?
I'm keen to hear from you since I'm working with exactly the same aperture and f ratio.
Thanks mate.
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