Physics 1230: Light and Color Ivan I. Smalyukh, Instructor Office: Gamow Tower, F Phone: Lectures: Tuesdays & Thursdays, 3:30 PM - 4:45 PM Office hours: Mondays & Fridays, 3:30 PM – 4:30 PM TA: Jhih-An Yang Class # 14 Chapter #4: Cameras & Photography

2 Equivalent exposure settings (same light) ¼ sec. lets subjects move Background in focus (good depth of field) 1 / 250 sec. stops motion Background out of focus

3 Which f-number gives half the light of f-4? A.f-2 B.f-2.8 C.f-4 D.f-5.6 E.f-8 f = F/D, so you need a LARGER f-number for less light. 5.6 is sqrt(2) smaller than 4, so twice the light.

4 Which pair gives the same amount of light? 1/30 sec. and f number 4 and a)1/120 sec. and f-1 b)1/120 sec. and f-2 c)1/120 sec. and f-4 4x more light for ¼ the time.

55 Lec. 9: Ch. 4 –The Camera and Photography\ Camera parts Lenses for cameras Controlling light Photography as art Photography as science We are here 5

66 Albert Bierstadt Looking Down Yosemite Valley Oil painting 1865

77 Ansel Adams

88 William Henry Jackson. Mountain of the Holy Cross Photography replaced painting to describe the western US Albert Bierstadt Looking Down Yosemite Valley Oil painting 1865

99 Wright Bros., 1903 Photography as proof. Jackalope, 2003?

10 Alfred Stieglitz Photography as art

11 Edward Steichen, Glamour photography

12 Edward Weston Compare to 15 th century painting with folded cloth

13 Imogen Cunningham Ansel Adams by Cunningham

14 “Fine focus” Means directional lighting “Soft focus” (not out of focus) Means diffuse lighting

15 Ansel Adams Snake River 1942

16 Lec. 12: Ch. 4 –The Camera and Photography Camera parts Lenses for cameras Controlling light Capturing images Digital images We are here 16 How do we capture and save the image?

Cameras existed for hundreds of years (pinhole and lens versions) The revolution (early 19 th century) was FILM: The method to store and reproduce the images. Nowadays, we rarely use films 17

18 Ansel Adams

Digital Image Storage: The CCD 19 CCD: “Charge Coupled Device”. Electronic device for storing images Light sensor area Wires go to computer memory.

Digital Image Storage: The CCD 20 CCD: “Charge Coupled Device”. Electronic device for storing images Light sensor area Notice the colors. RGB colored filters in front of the sensors. The Bayer filter.

Digital Image Storage: The CCD 21 CCD: “Charge Coupled Device”. Electronic device for storing images Rectangular array of PIXELs Typical array is several thousand by several thousand. 1000x1000 = 1,000,000 Pixels, OR 1 MegaPixel.

For photography of objects at different distances from us we use A. Camera with CCD that has at least 5 megapixels; B. Small aperture (large f- number); C. Large aperture (small f- number); D. Short exposure; E. A, B, C, & D

For photography of moving objects we use A. Camera with CCD that has at least 5 megapixels; B. Small aperture (large f- number); C. Large aperture (small f- number); D. Short exposure and larger aperture; E. A, B, C, & D

Extra credit questions What settings we use for small depth of field? What settings we use to make photos late in the evening (not much light)? What would you do to make a photo during a very sunny day? Explain how the photo on the left was done

25 Review: To help you in your preparation for the exam (since many of you find the problems on lenses and curved mirrors somewhat difficult, we briefly review only this part) Exam time: Regular class time on Tuesday, Oct 11

30 Ray Tracing: One method to understand spherical mirrors and lenses. Example: (A)Or (B): The image is LEFT or RIGHT of the lens. The image is REAL or VIRTUAL. This device is the ‘magnifying glass’. The image appears larger than the object.

31 Ray Tracing: One method to understand spherical mirrors and lenses. Example: What is the magnification? SOSO SISI SISI is the image height SOSO is the object height Ray tracing plus a ruler to measure things and you can determine magnification.

Object distance, image distance, focal length 32 XiXi XoXo F

Magnification formula S 0 = object height S i = image height Note the similar triangles. 33 Demo: big mama lens and bulb We do the following: Image on opposite side of lens? X I is positive (otherwise negative) Image on opposite side of axis? S I is negative. (otherwise positive) Object lengths are ALWAYS POSITIVE.

The lens equation: The land of “One-Over-Everything!” F = focal length X O = object distance X I = image distance Usually, F and X O are given. We want to find X I 34 Distant objects: Let X o be very large, say 1,000,000 meters. Then 1/X o = , which is very small. You can ignore it. Then For distant objects, the image is at the focal point (ask a burnt ant) Demo: find focal length of lenses

35 Exam time: Regular class time on Tuesday, Oct 11 Good luck on the exam! P.S. At home, go through the Photography guide on the next two slides