Scuba contact lenses

"Mike Painter" <mdotpainter@att.net> wrote in message
news:Qrgob.21108$Ec1.1907200@bgtnsc05-news.ops.worldnet.att.net...
>
> "Chris Guynn" <chrisguynn@sbcglobal.N.O.S.P.A.M.net> wrote in message
> news:03bob.85$V82.51@newssvr23.news.prodigy.com...
> <snip>
> >
> > As I understand it, this sounds like much the same phenomenon you
> experience
> > when you see the moon just over the horizon. It looks enormous. If you
> > photograph it, it is normal sized. From what I understand, your mind is
> so
> > used to seeing this get smaller as they approach the horizon that when
> > something doesn't (the moon), your brain says it must have expanded and
so
> > you see an even larger moon. Or something like that...
> >
>
> Not at all. In fact the next time you see the moon like that turn around,
> bend over and look at it between your legs. Bang, the moon appears normal.
> It is an optical illusion and looking at it in a different manner breaks
the
> illusion.
> The between the legs thing *really* works but any odd angle works.

Woudn't that also fit into what I said? Since you aren't used to looking at
things from that angle, you see what is actually there...

>
> In diving objects actually are magnified as light passes from water to
air.
> That's why the camera always must be focused to the apparent distance
rather
> than the real distance.
> But our brains can learn to ignore the difference.

True, but couldn't that be basically the same concept? We learn to see it's
actual distance instead of its apparent distance...

Either way, it's pretty neat.

>
>

--
Posted via Deeper Blue [ http://www.deeperblue.net ]
freedive.scuba.travel - The Online Resource for the Underwater World

Visual perception. This is the way in which the visual system and higher
order cognitive processes interact to give the visual world, as an
individual perceives it. Very complicated, speak to a psychologist!

Visual optics. Theoretically you could manufacture a pair of contact
lenses to enable clear vision underwater without the use of a mask. The
reason this is necessary is down to the fact that the human eye depends
on the difference in refractive index of cornea (the part of the eye
responsible for the majority of its refractive power) compared to the
air, which is removed underwater since the cornea and water have
approximately the same refractive index. Assuming the eye in question is
emmatropic (has no need for a spectacle correction) the cornea to air
interface is responsible for about 45D of refractive power, therefore,
one would need to produce a contact lens of this power which is no mean
feet! In addition to this, there would be the practicalities of keeping
the lens in situ while submersed. This would require a scleral lens, as
it would not be possible with standard hard or soft lenses. Other
potential problems would be the physiological implications of such a
lens on the cornea plus the problem of a visual correction while above
the water!

In summary, I think you would be better off with a simple face mask!



--
Posted via Deeper Blue [ http://www.deeperblue.net ]
freedive.scuba.travel - The Online Resource for the Underwater World

På Mon, 27 Oct 2003 16:14:56 GMT, skrev Marcin Dobrucki
<Marcin.Dobrucki@FAKE.nokia.com>:

> Tor wrote:
>> I don't want the mask at all..
>> I want to use lenses to see clearly without the mask.
>
> During the basic scuba course, you instructor should have explained
> that this is rather impossible. -- more stuff

You don't see the question here! Explain why a divemaster can explain this
complex matter?

Tor
www.gjerrestad.no

På 30 Oct 2003 15:00:27 -0600, skrev Erik <greatspirit63@yahoo.com>:

> Richard Whitcom wrote:
> > ". I should imagine contact lenses would be impossible as would
> glasses
>
> > purely due to the small size you'd need and the distance involved.
>
>
>
> Jaccque Mayol wore hard contact lenses that allowed him to see without
> an airspace. Umberto Pellizari and a few other people have used newer
> soft lenses for the same kind of freediving attempts. The company that
> makes the lenses charges about 10,000$ for a set, so usually a regular
> set of goggles goes over top, filled with water so that they don't get
> lost. The problem with them is that they can shift during the dive and
> the diver loses sense of direction. Erik Y.
>
>
>
> --
> Posted via Deeper Blue [ http://www.deeperblue.net ]
> freedive.scuba.travel - The Online Resource for the Underwater World


This is close Erik.
What are the idiots around this forum use for thinking. Now, im not aiming
at u folks thinking that this is possible

Use your brain for it's purpose.
--
Tor
www.gjerrestad.no