Section 4.1: Image Section 4.1: Image Formation in Eyes and Formation in Eyes and
Cameras Cameras
http://www.imaging-resource.com/PRODS/E50D/E50DA.HTM
http://www.eyedoctorguide.com/eye_care/eye_pupil.html
I CAN…I CAN…I can explain the use of concave and convex lenses in objects, such as cameras and eyeglasses.
Concave and Convex Concave and Convex LensesLenses
http://www.daviddarling.info/childrens_encyclopedia/light_Chapter4.html
How Light Gets InHow Light Gets In
Both eyes (natural) and cameras (artificial) are image-producing technologies.
A camera is very similar to how an eye works.
http://photoity.com/top-10-digital-cameras-for-photography-geeks/
Similarities Between a Similarities Between a Camera and an Eye Camera and an Eye
Human Eye
Camera
How does light enter?
Pupil Aperture
What controls the amount of light?
Iris Diaphragm
What interprets the image?
Retina Film
How is the light focused?
Lens Lens
Eye AnatomyEye 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.
http://perspectiveopticians.co.uk/2011/11/25/anatomy-of-your-eye/
Iris Controls the Light 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.
http://www.thenakedscientists.com/forum/index.php?topic=50610.0
When Light Gets Inside…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
RodsHighly 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. http://www.gamefaqs.com/boards/640108-assassins-creed-iii-liberation/64500498
Cones
Rods and ConesRods and Cones
Cones can’t function in low light, so we only see shades of grey in low light because only rods are stimulated.
http://hypervocal.com/entertainment/2012/sinfully-crafty-diy-projects-inspired-by-fifty-shades-of-grey/
https://whin111.wordpress.com/page-5-the-light-is-on-albeit-dim/
Focusing the LightFocusing the LightIn 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 ProducedImages 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.
http://www.eetimes.com/author.asp?doc_id=1284549
Correcting Vision ProblemsCorrecting Vision Problems
Nearsightedness (Myopia) Image falls short of the retina. Trouble seeing distant objects. Corrected with concave lenses.
https://www.koofers.com/links/nearsightedness-test-do-you-see-einstein-or-
marily/
http://en.wikipedia.org/wiki/Myopia#mediaviewer/File:Myopia.gif
Correcting Vision ProblemsCorrecting Vision Problems
Farsightedness (Hyperopia) Image falls behind the retina. Trouble seeing near objects. Corrected with convex lenses.
http://www.bausch.com/your-eye-concerns/vision-correction/farsightedness-hyperopia#.VOgJqFPF8mc
AstigmatismAstigmatismAstigmatism Video
http://www.lasikmd.com/edmonton/candidate/eye-problems/astigmatism
Laser Eye SurgeryLaser Eye SurgeryThe lens is reshaped by a laser,
which helps focus light.
Lasik surgery
Night Vision GogglesNight Vision GogglesLow light is
intensified by phosphor-coated screen.
Looks green
http://rhode.meccahosting.com/~a0008087/Yukon%20Tracker%201x24%20Night%20Vision
%20Goggle%20Kit%20YK25025.htm
http://bestnightvisionbinocular.blogspot.ca/2015/01/exactly-whats-so-great-about-night.html
HomeworkHomeworkCheck and Reflect #2 (p. 235).
Go to Mrs. Pilipchuk’s website and print off the handout for section 4.2 for next class.
Differences Between a Differences Between a Camera and an EyeCamera and an Eye
Human Eye Camera
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
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