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determining aperture reduction from shorter truss tubes experimentally
Hi there,
I've got a 16" truss dob. The trusses are adjustable in four increments of 10cm. Currently it's on the second to lowest one. I'd quite like to get my Baader Mk V binoviewer going on it. However, even with Baader's 1.7 correcting lens for newts, it still won't quite achieve focus. I can put my truss tubes on their lowest setting, but I'm concerned I maybe inside the light cone from the mirror and trimming my aperture as a result.
Is there a way to experimentally figure out if this is the case and if so, how by how much? I feel like there should be a simple way but I just can't think of it.
Markus
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