1. Lab 10: Lenses 1.Focal Length 2.Magnification 3.Lens Equation 4.Depth of Field 5.Spherical Aberrations and Curved Focal Plane 6.Chromatic Aberration 7.Astigmatism (Optional) 8.Barrel and Pin Cushion Distortion (Optional) 9.Diverging Lenses

2. Lenses Lab Pay attention to quality of images in this lab –Photography needs good images on the film Do experiment #5 after all other experiments

3. Light Rays A source could be anywhere along the dashed line ????

4. Light Rays You locate the source by diverging rays!

5. Light Rays Observer: the converging point 1.makes diverging rays 2.appears to be the light source Converging point – image point Optical components

6. Light Rays Light rays from far away object appears to be...

7. Parallel Rays Nearly parallel! Huh?

8. Converging Lens Light rays deflect toward optical axis

9. Converging Lens Thick Thin A strong lens has a short focal length  Is it thicker or thinner?

10. Converging Lens optical axis parallel rays FF focal points focal length f parallel rays converge at F each lens has a unique f

11. Two Sides - Two Focal Points FF

12. Diverging Lens Light rays deflect away from optical axis

13. Diverging Lens Thick Thin A strong lens has a short focal length  Is it thicker or thinner?

14. Diverging Lens optical axis rays deflect away from optical axis

15. Diverging Lens F rays appear to come from point F F focal points focal length f

16. Ray Diagram Practice drawing ray diagrams for different lenses and object distances (o) in this lab

17. What is Ray Diagram? shows object (O), lens, and image (I) shows rays originating from an object using three easy rays, you can graphically determine image distance (i) and image size (L i )

18. Ray Diagram  1.Pick one point on object 2.Extend 3 rays in good direction

19. Ray Diagram  parallel center through F real image image (tip of arrow)

20. Image Quality  Out of focus No image Slightly out of focus Focused Sharp imageSmeared image

21. Ray Diagram  Object parallel through focal point center

22. Ray Diagram  Object Image (Virtual) rays appear to come from back of the lens

23. Expt 1: Focal Length Lens # 1 0 Screen Parallel light rays from far away light source Move lens until the image of light source appears on the screen

24. Magnification  Object How large? 10  larger or 0.5  larger? Magnification: ratio of image size to object size

25. Magnification  LoLo o LiLi i ray passing through center of lens How do you derive the magnification equation using the light ray passing through the center of the lens?

26. 3. Lens Equation (Formula) f: focal length o: object distance i: image distance Lens equation relates f, o, and i real ( i > 0) inverted image or virtual ( i < 0) upright image  o i O I f > 0  o i O I f < 0

27. Light Unit Plastic ruler is on the light source! Inner circle diameter: 10 mm mm Face view

28. Expt 4: Depth of Focus (Field) Move screen Find the range (depth) of good focus Light Unit Lens # 2? Aperture Top view

29. Expt 5: Spherical Aberrations and Curved Focal Plane Screen Light Unit Peripheral MaskCentral Mask Move lightly Aperture Lens # 1 Aperture Examine image qualities Top view

30. Expt 6: Chromatic Aberration Roscolux Filters Adjust screen Compare the position of good focus #27 Medium Red #83 Medium Blue Light Unit Lens # 2? Aperture Top view http://www.rosco.com/images/filters/roscolux.jpg