Re: Burning question

Hi KJ -
You wear glasses, right? Well, you should.
Your eye's shape is not perfect, and so rays reaching different zones
of the pupil land in different places on your retina. This causes a
blurring and loss of contrast of the type print you're looking at. Now
when you move your finger around, its edge occults some of those rays.
The remainder of the rays form an image that is no longer at the
full-aperture "average" position, and so the image seems to move
around. BTW, the dimmer the ambient light (or the less you're adapted
to it) the greater the effect because your pupil will be dilated,
exposing more zones of the lens.

You can use this effect to some benefit:
Place your thumb and forefinger together on each hand, then push these
four fingers together to form a small, diamond-shaped aperture. The
harder you push, the smaller the aperture. Now bring that aperture up
close to your eye. You will have super-resolution (but dim), and be
able to see distant ships or read the directions on an aspirin bottle
without glasses. This technique works really well to view the moon!

curiousmind wrote:
> Alright, let me see if i can word this right. I have observed that
if
> I close one eye, then hold up a finger around 5 inches from my face
> and focus on say a picture or piece of text lying on a desk, my
> finger is quite blurry, and when I move my finger around, the parts
> of the picture/text where my blurred finger are over "morph" so to
> say. It's almost like moving a very small magnifying glass around.
> If anyone know why this is, how this works, I would love to know. I
> seriuosly don't know where else to find this answer.
> thanks, kj
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