Digital Photography I

  • View
    17.957

  • Download
    0

Embed Size (px)

Text of Digital Photography I

  • Peter Liu - Digital Photography

    Peter Liu Photography

    Digital Photography IThe Basics

    Peter LiuPhotographykaiscapes.com

    Peter Liu - Digital Photography

  • PhotographyFrom two Greek words meaning drawing with light: phos ("light") graphis ("stylus", "paintbrush")

    Merriam-Webster:The art or process of producing images on a sensitized surface (as a film) by the action of radiant energy and especially light.

    Peter Liu - Digital Photography

  • Photography The art of capturing light as it falls on a subject or scene, and rendering it so that your viewer is moved by the result.

    Peter Liu - Digital Photography

  • Capturing LightHard Light high contrast, well-defined shadows

    Peter Liu - Digital Photography

  • Capturing LightSoft Light diffused, rich colors

    Peter Liu - Digital Photography

  • Capturing LightOverhead Light harsh shadows

    Peter Liu - Digital Photography

  • Capturing LightFront Light flat, lacks dimension

    Peter Liu - Digital Photography

  • Capturing LightSide Light evokes mood, accentuates shapes

    Peter Liu - Digital Photography

  • Capturing LightBack Light may need to fill, makes silhouettes

    Peter Liu - Digital Photography

  • Capturing LightOvercast Light low contrast, muted shadows, good for detail

    Peter Liu - Digital Photography

  • Characteristics Of LightQualityThe smaller the light source, the harder the light appearsThe larger the light source, the softer the light appears

    DirectionDetermines where shadows fall

    ContrastDifference between the lightest and darkest tones of the subject or image

    SourceAmbient daylight, tungsten, flourescent, firelightArtificial flash, tungstenIntensityReflectanceReflectivity of the subjectIntensity of the light sourceAngle of viewDistance of light source

    Fall-offIncrease distance, decrease light level (Inverse Square Law)

    Peter Liu - Digital PhotographyInverse Square Law When a surface is illuminated by a source of light, the intensity of the light at the surface is inversely proportional to the square of its distance from the light source.

    Fluorescent Tubes radiate light after absorbing ultraviolet light from mercury vapor emission, resulting in a green cast not visible to the naked eye.

  • Characteristics Of LightColorMixture of primary colors: Red, Green and Blue varies according to sourceWarm predominantly redCool predominantly blueExpressed in Kelvin (K):Incandescent ~ 3000KFluorescent ~ 4100KFlash ~ 5400KDaylightDirect Sunlight ~ 5200KCloudy ~ 6000KShade ~ 8000KReferred to as White Balance in digital photography.

    Peter Liu - Digital Photography

  • White Balance

    4100K (Fluorescent)3000K (Incandescent)5200K (Sunlight)8000K (Shade)5400K (Flash)6000K (Cloudy)

    Peter Liu - Digital PhotographyInverse Square Law When a surface is illuminated by a source of light, the intensity of the light a the surface is inversely proportional to the square of its distance from the light source.

    Fluorescent Tubes radiate light after absorbing ultraviolet light from mercury vapor emission, resulting in a green cast not visible to the naked eye.

  • Why Are You Telling Us All This??Because good photography depends on being able to execute two things well:

    ExposureComposition

    Peter Liu - Digital Photography

  • ExposureA combination of three factors sometimes known as the Photographic Triangle:Shutter SpeedApertureISOOr

    how quickly light is being captured through how big an opening onto how sensitive a surface

    Peter Liu - Digital Photography

  • ShutterA cameras shutter covers the hole through which light enters to expose the sensor or film.The shutter release button causes the shutter to open for a certain amount of time, then close again. Image source: www.howstuffworks.comImage source: VisibleDust

    Peter Liu - Digital Photography

  • Shutter Speed Fast1/1600 sec., stops action

    Peter Liu - Digital Photography

  • Shutter Speed SlowSilky, cool, edgy effects 1 sec.3 sec.1/3 sec.

    Peter Liu - Digital Photography

  • Shutter SpeedsOpen too long, photos are washed out (overexposed)Not long enough, photos are too dark (underexposed)Expressed in seconds: 1/8000, 1/4000, 1/2000 1/1000, 1/500, 1/250, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1 second, 2 seconds, etc. Each setting is half or double the speed of its neighbor.As the amount of available light decreases by half, the shutter speed needs to slow by double.As the amount of available light increases, the shutter speed needs to increase

    Peter Liu - Digital Photography

  • ApertureThe opening through which light enters the camera.Sometimes called an iris because it imitates the opening in the human eye.Image source: www.howstuffworks.com

    Peter Liu - Digital Photography

  • ApertureThe size of the opening is expressed as an f-stop number: 1.42.02.845.68111622 Each number represents an opening size that is half or double its neighborThe larger the number, the smaller the openingFor all the science types: the f-stop is actually a ratio between the diameter of the aperture in the lens and the focal length of the lens:

    e.g. f/2 on a 50mm lens says the aperture is 25mm. 50/25 = 2.(Source: A Tedious Explanation of the f/stop by Matthew Cole)For the rest of us: the size of the opening controls the depth of field in the photograph.

    Peter Liu - Digital Photography

  • Aperture And Depth Of Fieldf/5.6Shallow depth of fieldf/22Deep depth of field

    Peter Liu - Digital Photography

  • Aperture And Depth Of FieldCaused by refraction of the light hitting the edge of the openingRays scatter and overlap instead of going straight on its way to the sensor or filmThe camera sees multiple images, resulting in blur.The smaller the opening, the less surface available to scatter the light, resulting in less blur.Bottom line: the aperture is used to control how much of the scene is in focus.

    Peter Liu - Digital Photography

  • Aperture And Shutter SpeedThe following reciprocals will yield the same exposure:

    What changes is how much is sharp and in focus.

    f/2.81/500 sec.f/41/250 sec.f/5.61/125 sec.f/81/60 sec.f/111/30 sec.f/161/15 sec.f/221/8 sec.

    Peter Liu - Digital Photography

  • The Light MeterA device that assesses a scene and figures out the correct exposureModern cameras have them built-in External handheld models also availableEngaged when shutter is pressed halfwayMatrix/Evaluative, Center-weighted, Spot meteringLooks for 18% Grey or Middle GreyEasily fooled!

    Peter Liu - Digital Photography

  • Tricky Metering Situations

    Peter Liu - Digital Photography

  • Exposure CompensationUsed when the light meter is unable to evaluate the exposure as desired, or when correcting by whole stops is too muchUsually +/- 2 EV (Exposure Value) in steps of 0.3 EVAvailable on most cameras

    Peter Liu - Digital Photography

  • ISOSensitivity of the sensor or film to lightRepresented by a number assigned by the International Standards Organization (hence, ISO) 100, 200, 400, 800, etc.Again, each number represents double or half the sensitivity of its neighbor (Aint it wonderful!)The higher the number, the more sensitive to lightDigital photography is cool because you can change the ISO from shot to shot!

    Peter Liu - Digital Photography

  • Higher ISO = More Noise! ISO 3200

    Peter Liu - Digital Photography

  • SoExposure depends on:Shutter Speed how fastAperture how muchISO how sensitiveAnd color is a function of:White Balance how hot

    Peter Liu - Digital Photography

  • And

    Which camera you choose is a function of how much you want control those factors!

    Peter Liu - Digital Photography

  • CamerasTwo popular types of cameras on the market for the consumerPoint-and-shootSLR (Single-lens Reflex)

    Peter Liu - Digital Photography

  • Cameras

    Point-and-shootViewfinder separate from lensSmall and compactFixed lensShutter delayUsually fully automatic (some exceptions, like Olympus C-series)

    SLR (Single-lens Reflex)Based on 35mm designActual image seen in viewfinderInterchangeable lenses (more flexible composition)Ability to use filtersMore advanced metering and shutter systemLittle to no shutter delayAutomatic, Program (Scene), Shutter Priority, Aperture Priority and Manual modesFlash hot shoePro models may not have pop-up flash or Program (scene) modes

    Peter Liu - Digital Photography

  • Point-and-shoot Anatomy

    Viewfinder separate from lens (better to use LCD on digital)Actual image (as exposed) is not quite the same as in the viewfinderMuch simpler design than SLRs.

    Light PathLensCamera BodyViewfinder(front)ShutterSensor or FilmViewfinderFocal LengthLCD Screen(Digital)

    Peter Liu - Digital Photography

  • SLR Anatomy

    Through-the-lens (TTL) viewing (works like a periscope)Actual image (as exposed) is shown in the viewfinderMirror flips up when the shutter release is pressed, exposing the sensor (and blacking out the viewfinder)Reflex comes from the use of the mirrors in the viewfinder system.

    Light PathLensCamera BodyFocusing ScreenMirror (Pentaprism)Mirror (flips up)ShutterSensor or FilmViewfinderFocal LengthLCD Screen(Digital)

    Peter Liu - Digital Photography

  • Advantages Of DigitalInstant gratification (big fun factor) see your images right awayNo film cost shoot as many as you want, erase and shoot again (heck, its just pixels!)Convenience print, email, web, slide shows; no waiting around for the photos to come back from the sto