> I've got a question about focusing Dobsonian binoculars. I
> realize that the scopes must move perpendicular to each other
> to adjust them for different inter-occular spacings. My
> question is: Does the focus of each scope need to be
> adjusted so that the surface of each eyepiece is the same
> distance from each eye? If someone has the same vision in
Richard,
I have this problem with my 8" F8's. I have about 2 dioptres more short sight on the left tha the right. I compromised by setting the left focal position slightly further out so that people with normal vision would have only slight inconvenience ( a slight tilt of the head accomodates ) and the eyepiece would be foreward of the right, when I have my glasses off. No one has comlplained yet. If you have any more focus difference than this I would recomend having a weak lens made to slip over one eyepiece which will account for the focus differnce between your eyes.
The interocular distance is fairly insensitive for large exit pupils, as you pupil can miss some of the beam without a heavy vignetting effect being visible. For 2mm and smaller exit pupil, I find the interocular distance must be well adjusted. A nice smooth adjustment motion helps here.
Mark