Will,The problem with longer f ratio's is you end up with a long small scope or a really long big scope.
Kowa's specs for the 66A include the TE11WZ 25-60x zoom. The length is 36,5 cm and weight is 1500 g.
For comparison, my ATM 65HD (also magnesium body) measures 36cm with the shortish 30x W.
I put the ATM on the scales without its eyepiece, but with the TE11WZ from my 883 and measured 1390 g.
The extra weight of the 66A can probably be attributed to the generously dimensioned prism also used on the 88 and 99.
Btw, I'm surprised that this new release has generated comparatively little interest so far. I regard the ATC/STC as something of an expensive gimmick but that thread has 411 replies and 61K clicks since September.
If I didn't already have two scopes the 66A would be my one and only choice; better than everything smaller and better than some larger.
It's even got two threads in the foot, just to please Bill Atwood.
Regards,
John