Chapter 25 Optical Instruments CHAPTER 25 Conceptual Questions C1 Using a camera with a fixed focal length lens how will decreasing the f number affect the depth of field and the intensity of the light reaching the ccd or film a The depth of field will increase as will the intensity of light reaching the ccd b The depth of field will increase but the intensity of light reaching the ccd will decrease c The depth of field will decrease as will the intensity of light reaching the ccd d The depth of field will decrease but the intensity of light reaching the ccd will increase C2 A person can see well in the distance but cannot do so at an arm s length distance To correct this lenses that are having a power could be used a thicker at their center than at the edges positive b thicker at their center than at the edges negative c thinner at their center than at the edges positive d thinner at their center than at the edges negative C3 The eye parts iris retina cornea and ciliary muscle play roles related to and in a camera a the aperture the lens the ccd focusing b the aperture the ccd the lens focusing c the lens the aperture focusing the ccd d the lens focusing the ccd the aperture C4 A magnifying lens of power d in diopters gives what magnification when the viewing eye is relaxed assuming a near point of 25 cm a 25d b 0 25 d c d 4 d The correct answer is not given C5 Why is it easier to see fine print in brighter light than in dimmer light a This is not so it is easier to see fine print in dimmer light than in brighter light b Because the power in diopters of the eye increases as the light intensity increases c In brighter light the longer wavelengths dominate d In brighter light the f number of the eye increases 173 Chapter 25 Optical Instruments 25 1 The Camera 1 What is the f number of a camera lens that has an aperture opening diameter of 0 30 cm and a focal length of 3 0 cm a 0 10 b 0 80 c 10 d 15 2 A camera lens is initially set at f 16 for a shutter speed of 1 60 s If the amount of lighting on the subject is unchanged and the lens is set at f 5 6 what is the proper shutter speed at this setting a 1 500 s b 1 250 s c 1 8 s d 1 16 s 3 Tripling the aperture diameter of a camera lens will change the f number by what factor a 1 9 b 1 3 c 3 d 9 4 Tripling the focal length in a telephoto lens while keeping the aperture size constant will change the f number by what factor a 1 9 b 1 3 c 3 d 9 5 Doubling the aperture diameter of a camera lens will change the light intensity admitted to the film by what factor a 0 25 b 0 50 c 2 0 d 4 0 174 Chapter 25 Optical Instruments 6 Doubling the focal length of a telephoto lens while holding aperture size constant will change the light intensity admitted to the film by what factor a 0 25 b 0 50 c 2 0 d 4 0 7 Tripling the f number of a camera lens will change the light intensity admitted to the film by what factor a 1 9 b 1 3 c 3 d 9 8 I take two pictures of my dog Kaycee I use the same film and level of illumination for both pictures but I double the f number for the second picture By what factor will the required time of exposure change if the film is to receive the same total light energy a 0 25 b 0 50 c 2 0 d 4 0 9 A camera uses a a converging lens to form a real image b converging lens to form an imaginary image c diverging lens to form a real image d diverging lens to form an imaginary image 10 Changing the f number of a camera by two stops by going from f 8 to f 16 will change the intensity of the light hitting the film by a factor of a 4 b 2 c 1 2 d 1 4 11 A 1 5 m tall woman stands 5 0 m in front of a camera with a 4 0 cm focal length lens What is the size of the image formed on film 175 Chapter 25 Optical Instruments a 2 4 cm b 1 9 cm c 1 2 cm d 0 60 cm 176 Chapter 25 Optical Instruments 12 A high f number a allows a larger depth of field b allows using a slower shutter speed c causes more spherical aberration d is not related to any of the above options 13 A camera has a lens of focal length 50 mm and a speed of f 2 0 What is the diameter of the lens a 13 mm b 25 mm c 50 mm d 100 mm 14 A camera is used to photograph the full moon which has an angular diameter of 0 51 The image on the film is 3 1 mm in diameter What is the focal length of the lens a 6 3 mm b 13 mm c 350 mm d 710 mm 25 2 The Eye 15 A diverging lens will be prescribed by the eye doctor to correct which of the following a farsightedness b glaucoma c nearsightedness d astigmatism 16 The ciliary muscle is instrumental in changing the shape of which eye part a iris b lens c pupil d retina 17 The ciliary muscle of the eye is relaxed under which condition a eye is focused on a distant object b eye is focused on a nearby object 177 Chapter 25 Optical Instruments c subject being viewed is well illuminated d subject being viewed is dimly illuminated 178 Chapter 25 Optical Instruments 18 The pupil of the eye reduces in size under which condition a eye is focused on a distant object b eye is focused on a nearby object c object viewed is well illuminated d object viewed is dimly illuminated 19 A diverging lens will be prescribed by the eye doctor to correct which of the following a myopia b presbyopia c hyperopia d astigmatism 20 Which term below identifies the eye defect characterized by an inability to see distant objects clearly a myopia b presbyopia c hyperopia d astigmatism 21 Which term identifies the defect where the lens produces a line image of a point source a myopia b presbyopia c hyperopia d astigmatism 22 Which eye defect is corrected by a lens having different curvatures in two perpendicular directions a myopia b presbyopia c hyperopia d astigmatism 23 A lens with a focal length of 20 cm has what power a 5 0 diopters b 6 7 …