1. The pinhole camera and the simple camera Objectives: You will be able to : Explain why we need a lens in a camera describe the parts we need in a simple camera Describe what the parts are used for

2. Draw the ray diagram that produces the image at the back of the camera. Is the image: - upright or inverted -magnified or diminshed -real or virtual

3. You are going to make a pinhole camera and then try to improve it by adding a lens. First you must find the focal length of your lens. Then choose a box with about the same length as the focal length of your lens. Then make a pinhole camera

4. The pinhole camera You can see images on the translucent screen with a pinhole camera. Think! How could you take photos with a pinhole camera? What would happen if you made the hole bigger? What would happen if you made the hole smaller?

5. The pinhole camera If you make the hole bigger, the picture will be lighter but more blurred. If you make the hole bigger, the picture will be darker but more in focus. How can you get round this problem?

6. The camera A real camera uses a lens! What are the parts of the real camera used for?

7. The eye How is the eye similar to the camera? Which parts does the eye have? Lens? Film? Focussing ring? Shutter? Diaphragm?

8. How does the eye work?.

9. The parts of the eye Cornea, aqueous humour and lens: focus the light The lens: adjusts the focus for objects which are near or far away The ciliary muscle: Changes the shape of the lens so that it can change the focus. The retina: Detects the image (rods and cones are sensors) The optic nerve: sends picture to brain The iris: Changes size of pupil – lets more or less light in Vitreous humour: is watery and gives the eye its shape The sclera and the chroroid: protect the eye

10. CameraLensUse Match the parts of the camera and the eye and their uses: Lensciliary muscleretinairisfilmdiaphragmlens focussing ring

11. Problems with the eye Myopia (Short-sightedness) People who are short-sighted cannot see objects which are far away. They focus the image in front of the retina. How can you correct this?

12. Problems with the eye Myopia (Short-sightedness) People who are short-sighted cannot see objects which are far away. They focus the image in front of the retina. How can you correct this?

13. 6. CONCAVE (DIVERGING) LENS Used in spectacles: Short sight ‘Myopia’Long sight ‘Hyperopia’ Eye lens too strong: spectacle lens diverges light to bring back into focus Eye lens too weak: spectacle lens converges light to bring back into focus