>It took me a while to find it - the topic of T-stops was a recent discussion
>among the astrophotographers. Without going into the arithmetic, the T-stop
>for the Rubinar is f/6.68. This assumes 100% reflectivity and 100%
>transmission by the mirrors and lenses. FWIW, I get a 31percent central
>obstruction for a primary diameter of 90mm and a central obstruction of
>50mm.
>
>John P
That's right, I miscalculated the percentage.
Matthias
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|