I'm looking for glasses or contactlenses for use when scuba diving, in the
meaning... no ekstra mask.
Is this possible? Does anybody know where to find more info on this
subject...

I'm looking for glasses or contactlenses for use when scuba diving, in
the meaning... no ekstra mask. Is this possible? Does anybody know
where to find more info on this subject...

It would be nice to dive without the mask
I know about a tribe of sea gipsy called "chao ley" they have learnt
to see better below water as kids.

I'm looking for glasses or contactlenses for use when scuba diving, in the
meaning... no ekstra mask.
Is this possible? Does anybody know where to find more info on this
subject...

It would be nice to dive without the mask
I know about a tribe of sea gipsy called "chao ley" they have learnt to
see better below water as kids.
--
Tor
www.gjerrestad.no

No, it isn't possible. The cornea of your eye is a strong positive
(focusing) lens, and without this, your eyes won't focus correctly. The
focusing action depends on the bending of light at the surface, which in
turn depends on the difference of refractive index between the air and
the cornea. Immersing the cornea in water changes the index difference
enormously, changing the focusing action, and putting your eyes _way_
out of focus, to the extent that your maximum accommodation can't bring
the focal point in as close as optical infinity, IIRC.

"Tor" <tor@gjerrestad.no> wrote in message
news:oprxrfjw06i0ca9r@news.chello.no...

I'm looking for glasses or contactlenses for use when scuba diving, in the
meaning... no ekstra mask.
Is this possible? Does anybody know where to find more info on this
subject...

It would be nice to dive without the mask
I know about a tribe of sea gipsy called "chao ley" they have learnt to
see better below water as kids.
--
Tor
www.gjerrestad.no

The main refraction in the eye occurs at the eye/air interface. If you
immerse it in water you greatly lengthen the focal length.
This makes what you want virtually impossible.
Note that diving masks have a *flat* outer surface so the focal length is
constant in air & water, you need to see with it on in both.

Further more, since with experience dives can last a long time (I think my
longest is 1hr 20 mins on a shallow dive, 15 litre 230 bar) I think you
would find direct contact with water intensely uncomfortable for that
period.

I have heard the story about pearl divers etc, but not seen it verified. It
related to divers not using scuba, so short dives, but I do not see how they
could accomodate to compensate for switching n=1 top n=1.33! It *may* be
that the adaptation is really in *using* the blurred out of focus
informnation efficiently for a given purpose (finding whatever they are
after) not in actually focussing the eye.

Im around 250 dives, sadly all with a custom mask.

Harvey

"Phil Hobbs" <pcdhSpamMeSenseless@us.ibm.com> wrote
No, it isn't possible. The cornea of your eye is a strong positive
(focusing) lens, and without this, your eyes won't focus correctly. The
focusing action depends on the bending of light at the surface, which in
turn depends on the difference of refractive index between the air and
the cornea. Immersing the cornea in water changes the index difference
enormously, changing the focusing action, and putting your eyes _way_
out of focus, to the extent that your maximum accommodation can't bring
the focal point in as close as optical infinity, IIRC.

But if you're myopic (i.e. the cornea/lens combination is effectively
"too strong"), then perhaps the "weakening" of that optical system by
immersion into a medium of higher refractive index, would compensate,
and allow _better_ vision. What do you all think?

It's not clear (P.I.) to me just _how_ myopic you'd need to be though.
Probably very. Myself, I take -8.00, -7.50 (L, R) contacts.

Comments?

But if you're myopic (i.e. the cornea/lens combination is effectively
"too strong"), then perhaps the "weakening" of that optical system by
immersion into a medium of higher refractive index, would compensate,
and allow _better_ vision. What do you all think?

It's not clear (P.I.) to me just _how_ myopic you'd need to be though.
Probably very. Myself, I take -8.00, -7.50 (L, R) contacts.

Comments?

I have heard the story about pearl divers etc, but not seen it verified. It
related to divers not using scuba, so short dives, but I do not see how they
could accomodate to compensate for switching n=1 top n=1.33! It *may* be
that the adaptation is really in *using* the blurred out of focus
informnation efficiently for a given purpose (finding whatever they are
after) not in actually focussing the eye.

"Harvey" <xh.ruttx@ecs.soton.ac.uk> writes:

I have heard the story about pearl divers etc, but not seen it verified.
It
related to divers not using scuba, so short dives, but I do not see how
they
could accomodate to compensate for switching n=1 top n=1.33! It *may* be
that the adaptation is really in *using* the blurred out of focus
informnation efficiently for a given purpose (finding whatever they are
after) not in actually focussing the eye.

I've seen a photograph of one of therse divers in Nature or Science
(cannot remember which one) some issues ago where you clearly can see
that the pupil is VERY narrow. In the text to the picture was said
that the ability to have a very tiny pupil is related to the ability
to have a better sightness (don't know whether this is the vcorrect
word in english) under water. I do not know whether this very small
pupil acts as a kind of camera obscura as the diameter of the pupil
was not given...

Armin Lambacher

I'm looking for glasses or contactlenses for use when scuba diving, in
the meaning... no ekstra mask.
Is this possible? Does anybody know where to find more info on this
subject...

It would be nice to dive without the mask
I know about a tribe of sea gipsy called "chao ley" they have learnt to
see better below water as kids.

På Tue, 28 Oct 2003 16:48:58 +0100, skrev Tor <tor@gjerrestad.no>:
Could it be possible with glasses instead...
If anyone could draw (and refer to a www site) an illustration i'd be very
(something like white ligt through a prism kind of illustration.)

Could it be possible with glasses instead...
If anyone could draw (and refer to a www site) an illustration i'd be very
(something like white ligt through a prism kind of illustration.)

--
Tor
www.gjerrestad.no

"Harvey" <xh.ruttx@ecs.soton.ac.uk> wrote in message
news:<3f9eb325@news.ecs.soton.ac.uk>...
"Tor" <tor@gjerrestad.no> wrote in message
news:oprxrfjw06i0ca9r@news.chello.no...

I'm looking for glasses or contactlenses for use when scuba diving,
in the
meaning... no ekstra mask.
Is this possible? Does anybody know where to find more info on this
subject...

It would be nice to dive without the mask
I know about a tribe of sea gipsy called "chao ley" they have learnt
to
see better below water as kids.
--
Tor
www.gjerrestad.no

The main refraction in the eye occurs at the eye/air interface. If you
immerse it in water you greatly lengthen the focal length.
This makes what you want virtually impossible.
Note that diving masks have a *flat* outer surface so the focal length
is
constant in air & water, you need to see with it on in both.

Further more, since with experience dives can last a long time (I think
my
longest is 1hr 20 mins on a shallow dive, 15 litre 230 bar) I think you
would find direct contact with water intensely uncomfortable for that
period.

I have heard the story about pearl divers etc, but not seen it
verified. It
related to divers not using scuba, so short dives, but I do not see how
they
could accomodate to compensate for switching n=1 top n=1.33! It *may* be
that the adaptation is really in *using* the blurred out of focus
informnation efficiently for a given purpose (finding whatever they are
after) not in actually focussing the eye.

Im around 250 dives, sadly all with a custom mask.

Harvey

Harvey,

That is a very interesting comment about the divers not actually
focusing, instead adapting to their environment based on familiarity
with certain aspects of the sea and their purpose for diving. And you
are right...their dives are not scuba dives. They dive in for only a
few minutes.

I know of divers in the Arabian Gulf that do this. They actually hunt
for pearls (oysters). So, they actually know where exactly to dive in
and upto what depth. They do have a higher lung capacity.

Sorry, Tor...but I don't have an answer to your question which is
quite an interesting question. Hope someone out there knows more about
the physics to give a more technical answer.

max.