Drawing lessons - illustrated lesson notes for teachers and students

Grapes, cherrys and the eyeball

3-3 THE GRAPE, THE CHERRY AND THE EYE

The eye is a ball with the iris (dark part) forming a slight projection like a boss. The pupil is not

a color but a dark shadow, a hole that allows light into the eye.

An attribute of the eye is the that it is translucent. This can lead to the following paradox:

when the light strikes the iris at an angle the highlight appears to be surrounded by dark even

though being round, that side is facing the light.

There are two layers to the outer eye. There is the cornea, and the lens. Light might very

easily pass through the cornea, and reflect off the lens causing a hightlight at odd locations on

the cornea. Both these stuctures bend light to some extent; the lens obviously bending light

more than the cornea. A hightlight on the cornea should show up on the opposite side of the

cornea as a reflected hightlight just as it does in glass.

The light that is seen in the iris of the eye opposite the highlight is transmitted light, which is

seen also in a glass or bottle of wine, or any container of transparent liquid. It works the same

with a grape. The iris of an eye is likewise a container of transparent liquid. Light passes

through it and reflects off the inside of the back of it, 180 degrees opposite the entry point.

The highlight itself is the reflection of the light source from the moist outer surface of the eye.

Of course this only occurs when the eye is in the light.

So the side opposite to the highlight often seems lit up, although it is in shadow.

The proper rendering of this effect gives the eye an aqueous and luminous quality, which is not

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