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Reading the responses to this thread, leads me to ask a question, because I haven't kept up with things.
If one buys a 12' dob which can be used for prime focus photography, doesn't that mean that for the same focal length, the primary mirror has to be closer to the focuser, which in turn would mean that the secondary mirror has to be bigger, resulting in less contrast from that dob when viewing planets?
I figure that there would have to be a trade -off somewhere, or manufacturers would have been making dobs that could be used for photography years ago.
Cheers,
Renato
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