Section 4.1: Image Formation in Eyes and Cameras ml

Class Website

I CAN… I can explain the use of concave and convex lenses in objects, such as cameras and eyeglasses.

Concave and Convex Lenses

How Light Gets In Both eyes (natural) and cameras (artificial) are image-producing technologies. A camera is very similar to how an eye works. photography-geeks/

Structures and Functions EyeCamera

Anatomy of a Camera and an Eye

Similarities Between a Camera and an Eye Human EyeCamera How does light enter? PupilAperture What controls the amount of light? IrisDiaphragm What interprets the image? RetinaFilm How is the light focused? Lens

Eye Anatomy The pupil is the opening; the amount of light that enters is controlled by the iris. The iris is made up of a circular band of muscles. your-eye/

Iris Controls the Light In bright light the iris constricts, becoming smaller, and reduces the light. In dim light the iris dilates, becoming larger and increases the light.

When Light Gets Inside… To see, the light must hit the sensitive retina at the back of the eye, which has 2 types of light-sensitive photoreceptors: 1) Rods and 2) Cones Rods  Highly sensitive to small amounts of light (dim light).  Allows for seeing in the dark (when there is enough light reflected).  More rods on the outside of the retina.

 Sensitive to bright lights, and they detect colour.  Almost exclusively in the retina. Patcharaporn Ch. Own Work. creed-iii-liberation/ Cones

Rods and Cones Cones can’t function in low light, so we only see shades of grey in low light because only rods are stimulated. projects-inspired-by-fifty-shades-of-grey/ light-is-on-albeit-dim/

Give it a Try (p. 233)

Focusing the Light In order to form a clear and sharp image, the focal point must land on the retina. In the eye there are muscles that control the shape of the lens.

Images Produced In a camera the lens is moved forward and backward. The upside-down image produced by the lens is not a problem because the brain interprets the world right-side up, and film can be developed either way.

Correcting Vision Problems Nearsightedness (Myopia)  Image falls short of the retina.  Trouble seeing distant objects.  Corrected with concave lenses. you-see-einstein-or-marily/

Correcting Vision Problems Farsightedness (Hyperopia)  Image falls behind the retina.  Trouble seeing near objects.  Corrected with convex lenses.

Review Can be corrected with a concave lens. Can be corrected with a convex lens.

Astigmatism Astigmatism Video problems/astigmatism

Review Normal Vision and Vision Problems Reading Between the Lines Activity

Laser Eye Surgery The lens is reshaped by a laser, which helps focus light. Lasik surgery

Night Vision Goggles Low light is intensified by phosphor-coated screen. Looks green %201x24%20Night%20Vision%20Goggle%20Kit%20YK25025.ht m whats-so-great-about-night.html

Homework Check and Reflect #2 (p. 235). Go to Mrs. Pilipchuk’s website and print off the handout for section 4.2 for next class.Mrs. Pilipchuk’s website

Differences Between a Camera and an Eye Human EyeCamera Flexible eyeball Filled with fluids Rigid camera body Light proof box Flexible lens Controlled by muscles Solid lens Not flexible Rods and cones Specialized cells which send images to the brain. Silver compound in film Retains image

Red Eye