Collmation and eye astigmatism - how perfect does it have to be on both axis? (1 Viewer)

Collmation and eye astigmatism-can eye astigmatism affect perceived collimation?

I tried to change the title in advanced settings but it wouldn't transfer to the forum page. Anyway...

I read somewhere (maybe cloudy nights?) (depending on magnification) about the allowable horizontal, and the more critical vertical convergence. Obviously each brain and eye package will differ re sensitivity and ability to pull everything together.

Question -
Let us assume that perfectly collimated binoculars are in use - Can astigmatism in ones eyeballs (without glasses) give a false looking vertical collimation when casually testing in the usual way...bins six inches to a foot away looking through them at a spire in the distance...or a flat horizontal line in the distance etc?...I'm not just referring to horizontal convergence, but can astigmatism in eyes make one side appear higher or lower? ...or worse - slightly rotate one or both images?

I have other questions but their validity depends on the answer to the above..

Regards
Rathaus

I'll stick my ignorant neck out and say that I don't think there is any relationship between the two things.

If there is, I'll learn something.

I think I would have to agree with Maljunulo , I would doubt astigmatism in eyes would make one side appear higher or lower, but then I'm no optician.

I'll stick my neck out a little further.. ;-)

The two things aren't related very closely,
but your brain aligns the two views to match each other based on matching details.
The more chances to match, the easier it is for the brain to align slightly un-collimated sides.
Seeing bad collimation, for example, is hard looking into a busy nearby forest.
(it does cause strain though)

So...if you are looking with uncorrected astigmatism
(or corrected but bad, since prescriptions are only an approximation),
and the affected image parts in each eye are different,
this would make you more sensitive to alignment errors.
If it is really bad, you may see bad alignment even if the binocs are aligned.
The brain would declare the two pictures to be different views.

OPTIC_NUT said:

The brain would declare the two pictures to be different views.

Click to expand...

But wouldn't that happen irrespective of the presence of binoculars?

Maljunulo said:

But wouldn't that happen irrespective of the presence of binoculars?

Click to expand...

Not as likely as when multiplied by a power and restricted in field width.
Unaided,your eyes see a huge field of view of a size natural to you
since birth. Many more clues to match and a many more angles to see.

OPTIC_NUT said:

Not as likely as when multiplied by a power and restricted in field width.
Unaided,your eyes see a huge field of view of a size natural to you
since birth. Many more clues to match and a many more angles to see.

Click to expand...

OK, that makes sense.

Thank you.

OPTIC_NUT said:

Not as likely as when multiplied by a power and restricted in field width.
Unaided,your eyes see a huge field of view of a size natural to you
since birth. Many more clues to match and a many more angles to see.

Click to expand...

Good stuff, thanks Optic Nut.