Thanks for the suggestion; I'll check it out.
One thing I already tried was looking at stereographs (SIRDS / SIS types especially the ones that do not require crossed eye viewing). I've no problem "seeing" the hidden 3D picture. But after that the focus problem remains.
It feels as if my eyes remain "locked" into farseeing mode only. When I try to focus at a page (say 20 - 30 cm away) I can't see sharp.
Presently, after some more tries, the problems seems to lessen. Could it be that a little eye practice - or getting used to - is required?
