1. Announcements 11/8/10 Prayer Exam 2 graded: median score 79 (after 2 pt curve) Found PpP book Still missing slinkies from: a. a.Stephen Grant b. b.Ty Beus c. c.Jon Mortensen d. d.Chris Read e. e.Roger Brown f. f.Tess Larson (I think she dropped; does anyone know her?)

2. Quick writing Draw the ray diagram for this situation: Converging lens, f = 20 cm, p = 80 cm

3. Quick writing Draw the ray diagram for this other situation: Converging lens, f = 20 cm, p = 15 cm

4. Quick writing Draw the ray diagram for this third situation: Diverging lens, f = -20 cm, p = 5 cm

5. Reading Quiz What’s the term used to refer to rays failing to focus because a lens is shaped incorrectly? a. a.elliptical aberration b. b.hyperbolic aberration c. c.parabolic aberration d. d.spherical aberration

6. Spherical Aberration Credit: the next several slides were produced by Dr. Durfee

7. Reducing Spherical Aberration with Aperture

8. Spherical Aberration

9. Reducing Spherical Aberration by Reversing Lens

10. Coma

11. 0 Degree Tilt

12. 10 Degree Tilt

13. 20 Degree Tilt

14. 30 Degree Tilt

15. 40 Degree Tilt

16. 40 Degree Tilt + Aperture

17. Thought question Red light coming from O produces an image at I. Where will blue light coming from O form an image? a. a.same place b. b.closer to the lens c. c.farther from lens Lens-makers’ eqn: Chromatic Aberration

18. How does a camera work? Simplest picture What if you leave out the lens? What’s a pinhole camera?

19. Reading Quiz What is the f-number of a lens? a. a.The focal length in meters b. b.The focal length in inches c. c.One over the focal length in meters d. d.The focal length divided by the diameter of the lens e. e.The focal length divided by 25 cm

20. Thought question How does the f-number of a lens relate to the half-angle of the “light cone” formed by parallel light entering the lens? a. a. b. b. c. c. d. d. e. e. 

21. Cameras: f-stops Which has the higher f-number? What’s the advantage of one over the other?

22. Thought question If you have trouble seeing things far away but can see close objects well, you are “near- sighted”. What kind of lenses do you need in your glasses? a. a.Converging lenses b. b.Diverging lenses

23. Near point vs. Far point Near point: how close can you see things comfortably a. a.Regular person: np  25 cm b. b.Farsighted person: np = much larger Far point: how far away can you focus on things a. a.Regular person: fp = infinity b. b.Nearsighted person: fp = much smaller – – For me, my fp  1 m (right eye), 0.5 m (left eye)