Also can’t do parallel, only cross view. I only have to use effort for the first few seconds, as soon as the two images are aligned, my focus snaps to it and I can relax and keep the focus without having to think about it.

It does cause some mild strain if I’m doing it for too long (like going through a book of these), but if I’m cross-eyed for a just a couple of minutes its no problem.

These are cross-view, your probably using the focus at infinity trick instead.