CS 39J > Schedule & Notes > Session 5 Detailed Notes
Class Summary<=p>

Fri=ay, February 06, 2009

9:2= PM

  1. Sean's Photo Critique: "Doe Library Black and White"
    • Dramatic perspective
    • He shot the picture wi=h a wider angle lens closer to the building than you realize
    • How does the viewer te=l?
      • It would not have bee= as dramatic if it weren't shot with the wide angle lens
    • Click the button above=the photo to view the photo properties details
    • The photo would not ha=e been as interesting without the lens
    • Shooting with a longer=angle lens would result in more parallel lines
    • Shooting with wider an=le lens would result in somewhat distorted, dramatic lines
    • Angling camera up and =own would change the "vertical-ness" of the lines
      • To keep lines vertica=, shoot the plane of the view of the sensor parallel to the object
      • If it weren't paralle=, then the lines would converge toward a vanishing point
  2. Christine's=Photo Critique: "Portrait"
    • The picture was taken =airly close to the subject
    • Lens was wide angle
    • Why am I seeing this?<=span>
    • Normal lens: approxima=ely 45-55 mm, focal length that is the same with the diameter of sensor
    • Generally speaking for portraiture, do not use a wide angle lens
      • Tends to exaggerate t=e perspective
      • Most people don't lik= to see their features exaggerated
      • Should shoot people w=th telephoto
      • Shallow depth-of-fiel= is preferred
    • Factors determining depth-of-field
      • Focal length
      • How close the camera =s to the subject
      • Aperture
  3. Betty's Pho=o Critique: "Barred"
    • ISO: sensitivity of fi=m to light
      • Sensitive: lower ligh=
      • Not sensitive:=/li>
      • ISO changes shutter s=eed
      • High ISO results in l=rger and grainier
    • F64 Group
      • Photographers concern=d with clarity, clear focus, etc. (without advanced technology)=/li>
    • How to get rid of the graininess?
      • Decrease shutter spee=
      • Tripod
        • Utilize stable thing= in the surrounding to substitute tripod
        • Hold your breath (or=take a deep breath, click camera while exhaling)
    • Longer the focal lengt=, the more movement there is
  4. Jonathan Ge=t's Photo Critique: "Girl in Field"
    • Camera Club: camera critiquing club
      • There is no limit to critiques
    • Composition
      • It would have been be=ter if the subject were looking into the frame
    • Lighting
      • The mountain behind is overly exposed
        • Which worked for the picture because it emphasizes figure
      • The subject is relati=ely dark in contrast to the mountains behind
      • The sky would have to=be more faded
      • Tried to get focus in=o the flowers
    • Incident light-meter
      • Using reflective ligh=, light reflected from the scene
  5. Next week's=photo assignment: big, colorful, active event
    • Suggestions: Chinese n=w year parade, sports events

 

 

 

2-20-2009

Fri=ay, February 20, 2009

1:1= PM

  1. Tradeoff in theory: refraction effect when the apert=re is small
  2. F stop: rat=o of focal length and aperture size (diameter of sensor)
    • Area is proportional t= the diameter (area goes up as the diameter squares)
    • Every stop doubles the=area (the amount of light)
    • In correspondence to t=e doubling, the F stop goes up by square root of two

     

    Exposure "stops" chart

Stops

Exposure

Shutter Spee=

Aperture

ISO Sensitiv=ty

-4

1/16x

1/1600s

f/22

ISO50

-3

1/8x

1/800s

f/16

ISO100

-2

1/4x

1/400s

f/11

ISO200

-1

1/2x

1/200s

f/8.0

ISO400

0

1x

1/100s

f/5.6

ISO800

+1

2x

1/50s

f/4.0

ISO1600

+2

4x

1/25s

f/2.8

ISO3200

+3

8x

1/12s

f/2.0

ISO6400

+4

16x

1/6s

f/1.4

ISO12800

  1. Color encompasses everything from physics to psychol=gy
  2. All the var=ables we have discussed so far do not discriminate against color
  3. Flash
    • Anytime there is a poi=t source of light, as with a flash, the light goes out like a lighthous=, so that when the photographer steps away from subject, the light diff=ses and spreads out
  4. Depth of fi=ld
    • The wider aperture, the shallower the depth of field
    • Larger the focal lengt=, the shallower the depth of field
      • Wide angle or telepho=o angle
      • Zooming in changes fo=al length
    • Focal distance<=li>
      • Shallow depth of fiel= is given if you are close to the subject
  5. Focus
    • In focus: single point=of the subject correspond to a single point on the sensor
      • Light converges at se=sor (neither before nor after sensor)
    • Focusing is done by mo=ing the lens back and forth, closer and further from subject
    • Bird photograph exampl=
      • You do not pick a foc=l subject, rather you pick a focal distance
      • Gradual drop off, inc=ease of bluriness as you move away from focal distance
    • Depth of field is the =ange of "focused area"
      • It is a plane<=li>
      • Generally, the two li=es marking the depth of field would be parallel to a sensor
    • Why can't everything b= in focus?
      • Because all the light= (at far limit of focus and near of focus) hit the lens at different angl=s, which translates into different points of convergence on the sensor<=span>
      • Circle of confusion: maximum non-convergence allowed to be "in focus"
        • The blurred circle of light that is indicative of light not in focus
    • When using a bigger le=s (larger aperture) the depth of field shrinks
    • Longer subject distanc=s mean larger depth of field range
    • Longer focal lengths m=an smaller depth of field range
  6. Assignment:=show different amounts of depth of field with the same subject

Assignment

Play around with depth of field. Remember the three things you can use to control it: aperture, focal length, and focus distance.