Hi, just to persist a bit on binoviewers and backfocus if I may. It is great you test your scopes with DenkIIs. I have one of these with the powerswitch and 2" OCS. Do you test with the Denk "middle Newtonian spacer" expanded ?? If you fully expand this hardly any extra focusser in-travel is needed, so most makes of Newtonian scopes should work. If you dont expand it, about 1.5" extra backfocus is needed. I hear alot of praise for the Baader MkV binoviewer as possibly being the closest to perfection bino that exists, and am thinking of getting one, now the euro is weak. It was originally manufactured by Zeiss, before they lost interest in amateur astronomy. There is a drawback though- the backfocus requirement is more than the Denk, but not hugely so (unlike the binos mentioned in Jim's response). Perhaps 1" more max. If you design the Webster scopes so the DenkII only just comes into focus after expanding the Denk middle spacer, then MkV is a no-go. It wont focus.
Related to this, someone on the web commented that the truss length on your scopes is adjustable- but I cant see how that could be so. In the event of just needing a tad more backfocus, this would do it.
Thanks guys, jon
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