For astronomical viewing this is unnecessary-- there is no up or down in space. :) For terrestrial viewing you can but an erecting diagonal which will make the image right side up. Here is one http://www.highpointscientific.com/stellarvue-1-25-quot-45-deg-erecting-prism-d1032?utm_source=google&utm_medium=cse&utm_term=STV-D1032&gclid=COv8-cSP58MCFdCmaQodUxwATQ
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For astronomical viewing this is unnecessary-- there is no up or down in space. :) For terrestrial viewing you can but an erecting diagonal which will make the image right side up.
Here is one
http://www.highpointscientific.com/stellarvue-1-25-quot-45-deg-erecting-prism-d1032?utm_source=google&utm_medium=cse&utm_term=STV-D1032&gclid=COv8-cSP58MCFdCmaQodUxwATQ