1. Announcements 11/7/11 Prayer Term project progress reports due Saturday night Slinkies! (Joshua M, Thomas, Mike, Rachael, and Ken—this means you!) Frank & Ernest

2. Class-designed problem p = _____ Lens 1: f = _____ Distance to Lens 2 = _____ Lens 2: f = _____ q 2 = ? Real or virtual? M tot = ? Upright or inverted? Ray diagram? (for first lens, anyway)

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

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

5. Quick writing Draw the ray diagram for this third situation: Diverging lens, f = -20 cm, p = 15 cm

6. 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

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

8. Reducing Spherical Aberration with Aperture

9. Spherical Aberration

10. Reducing Spherical Aberration by Reversing Lens

11. Coma

12. 0 Degree Tilt

13. 10 Degree Tilt

14. 20 Degree Tilt

15. 30 Degree Tilt

16. 40 Degree Tilt

17. 40 Degree Tilt + Aperture

18. 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

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

20. 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

21. 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. 

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

23. 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

24. Near point vs. Far point 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) Near point: how close can you see things comfortably a. a.Regular person: np  25 cm b. b.Farsighted person: np = much larger How to fix things with glasses? Farsighted: object at 25 cm  image at –np (converging lens) Nearsighted: object at  cm  image at –fp (diverging lens)