Digital Camera Basics NCLA Workshop

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Workshop presented by Emily Gore and Amy Rudersdorf at NCLA 2007

Workshop presented by Emily Gore and Amy Rudersdorf at NCLA 2007

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  • 1. Digital Camera Basics Amy Rudersdorf, NC State University Libraries Emily Gore, NC ECHO
  • 2. Digital Camera Basics
    • First half: mechanics of camera
      • Printed materials offer a basic guide
    • Second half: capture and lighting
      • Learning curve with digital camera
      • “ Craft of lighting” can take a lifetime to master
  • 3. Digital Camera Basics: Mechanics
    • Digital camera definition
      • A (primarily) still camera that captures images as discrete numbers (as opposed to variable intensities of light) by an array of charge-coupled devices (CCDs)
      • There is a fixed maximum resolution and number of colors that can be represented
  • 4. Digital Camera Basics: Mechanics
    • Analog photography
      • Negative or slide film is medium of capture
    • Digital photography
      • The “film” is a light sensor*
    • *Either a CCD (charge-coupled device) or CMOS (complementary metal oxide semiconductor)
  • 5. Digital Camera Basics: Mechanics
    • Light sensors
      • Convert light into thousands [or millions] of pixels
      • Pixels are tiny “dots” in which color/light data is stored
    • Capture occurs at single moment when shutter opens and closes
  • 6. Digital Camera Basics: Mechanics
    • Digital camera types
      • Point & shoot (P&S)
      • Single lens reflex (SLR)
      • Overhead/stationary
      • “Scan backs”
  • 7. Point & Shoot (P&S): Digital Cameras
    • Adjusts settings such as focus and exposure automatically
    • Some P&Ss offer manual controls
    • Compact
    • Typically has LCD* screen; may have viewfinder
    • LCD screen is excellent because it reduces image to two-dimensional view
    *Liquid crystal display
  • 8. Single-lens reflex (SLR): Digital Cameras
    • “Professional-level” cameras
    • View image through viewfinder
      • Much better for action, but limits the user to viewing through camera
    • Interchangeable lenses, higher quality optics
    • Larger than P&Ss
    • High ISO (light sensitivity)
    • Shutter response is faster than P&Ss
  • 9. Single-lens reflex (SLR): Digital Cameras
    • Mirror behind the lens reflects light coming into camera onto a ground glass screen
    • View through lens is seen through viewfinder
    • As shutter button is pressed, mirror lifts away to allow the light to reach image sensor and board where image is captured
  • 10. Single-lens reflex (SLR): Digital Cameras
  • 11. Overhead/Stationary: Digital Cameras
    • High-volume reproduction
    • High-quality reproduction
    • Single angle of view
    • Expensive
    • Programmatic
      • Mostly used for two dimensional art and books
  • 12. “ Scan-back” : Digital Cameras
    • Scanning sensor usually replaces film in large-format view camera
      • Scanning backs use a CCD sensor with a single row of pixels (sensing elements) that physically moves (scanned) across the image area, capturing one row of information at a time
    • Extremely high resolution and quality
    • Long capture time
    • Requires high-end optics, dedicated computer
    • $20,000+
  • 13. Choosing a Digital Camera
    • Most camera packages are not designed (primarily) for photographing objects
      • Standard lenses for “landscape” or people
      • May need to purchase a special lens, e.g., macro, to capture object detail
    • Manual exposure controls are essential
      • Automatic exposure will make white or black background grey
  • 14. Choosing a Digital Camera
    • Best if the camera can be “tethered” to a computer to allow live viewing of subject
    • Resolution is important, but only if the lens is of adequate quality and the camera is reasonably easy to use
    • Any digital SLR camera will meet requirements, a carefully chosen high-end P&S may suffice
  • 15. Digital Camera Basics: Resolution
    • DPI – dots per inch
      • The measurement of resolution of display, printing, and capture systems. As the “dot” (or pixel) rate doubles, the number of dots quadruples.
    • 100 dpi = 100 x 100 = 10,000 dots/pixels per inch
    • 200 dpi = 200 x 200 = 40,000 dots/pixels per inch
    http://photo.net/equipment/digital/basics/index?&for_print=1
  • 16. Digital Camera Basics: Resolution
        • A 5 x 7 inch photograph captured at 600 DPI will be how many pixels across on its longest edge?
  • 17. Digital Camera Basics: Resolution
    • ANSWER:
      • 7 inches x 600 = 4200 dpi on the longest edge
    • 8 x 10 inches at 300 dpi is the same as:
      • 4 x 5 inches at 600 dpi
      • 32 x 40 inches at 75 dpi
  • 18. Digital Camera Basics: Resolution
    • Different output devices require different resolution
      • Computer screens display at 72 dpi, although software may zoom in
      • Print devices print no higher than 300 dpi
        • Human eye cannot discern more than 300 dpi without magnifier
    • For digital preservation higher resolution is better
      • What sort of detail will a researcher need?
      • What will future technologies be able to display?
  • 19. Digital Camera Basics: Resolution
    • Confusing terminology!
      • Many printers offer high dpi, e.g., 1440 dpi
        • Refers to the microscopic pixels that make up the printing dots that are at 300 dpi or less
        • A printer with higher dpi offers more gradations of color , rather than higher resolution.
  • 20. Digital Camera Basics: Resolution and Megapixels
    • Megapixels
    • The n umber of pixels that comprise the surface of the image sensor
    • 1 megapixel = 1 million pixels
    • A 4.0 megapixel (or higher) can output an acceptable 8 x 10 inch printed image
      • 4 MP cameras have 2,289 x 1,712 pixels
        • 200 DPI image is 11.4” x 8.6”
      • 14 MP cameras have 4,500 x 3112 pixels .
  • 21. Digital Camera Basics: Resolution and Megapixels
    • Megapixels do not equal quality!
      • Camera manufacturers have greatly increased megapixel resolution, but noise has increased as well
    • Physically larger sensors have less noise
      • Digital SLR cameras offer noticeably better images compared to P&S cameras with higher numbers of pixels because P&Ss tend to be physically smaller cameras
    http://photo.net/equipment/digital/basics/index?&for_print=1
  • 22. Digital Camera Basics: File Formats
    • Digital images can be encoded in many ways
    • Most digital cameras record JPEG by default
      • Lossy compression
    • RAW format recorded from the sensor offers the most color and brightness detail
      • However, each camera manufacturer has a different standard
    • Some cameras can record TIFF files, which is the archival standard
      • Recommended
  • 23. Digital Camera Basics: Capture
    • Basic photography concepts
      • Aperture
      • Shutter speed
      • White balance
      • Lighting conditions (Exposure)
      • Bracketing
    • Other considerations
      • Background
      • 2d objects
      • 3d objects
  • 24. Digital Camera Basics: Capture
    • Aperture The size to which the shutter opens to let light in to the sensors
      • The smaller the f-stop number, the larger the opening
      • The larger the f-stop number the greater the depth of field, or perception of distance
      • Similar to squinting
    http://electronics.howstuffworks.com/how-to-digital-camera.htm
  • 25. Digital Camera Basics: Capture
    • Aperture (slide 2)
    f/32 f/# 0.5 0.7 1.0 1.4 2 2.8 4 5.6 8 11 16 22 32 45 64 90 128 f/5 For f/32 or smaller (number wise) or larger (apeture wise) -- you’ll need a tripod because the lens will be open for a good long time.
  • 26. Digital Camera Basics: Capture
    • Shutter speed The amount of time the shutter is open, allowing light to be exposed to the sensors
      • A fast shutter speed “freezes” movement
      • A slow shutter speed shows, or “blurs” movement
      • Measured in (parts of) seconds, e.g., 1/500
      • Indoor settings: somewhere around
      • 1/100 or 1/200 (you’ll need a tripod for
      • anything slower than 1/60 or so)
    http://electronics.howstuffworks.com/how-to-digital-camera.htm
  • 27. Digital Camera Basics: Capture
    • White balance In a camera, a setting that compensates for the differences in color temperature of the surrounding light.
      • White balance adjusts the image’s colors to look similar to daylight
      • You can set custom white balance using a “white card”
  • 28. Digital Camera Basics: Capture
    • White balance (continued) Indoor lighting is very different from natural lighting
      • Incandescent lights (light bulbs) are yellow-red compared to sunlight
      • Fluorescents tend to look green
    • P&S will try to make the background and the subject an even grey color
    http://www.scrapjazz.com/topics/Photography/Lessons/587.php
  • 29. Digital Camera Basics: Capture
    • Lighting conditions Aperture and Shutter Speed are determined by the availability and source of lighting
      • Bright, sunny or hazy light allows for smaller apertures and faster shutter speeds: f/16, 1/500
      • Overcast, close-up, back-lit subjects: f/5.6, 1/500
  • 30. Digital Camera Basics: Capture
    • Exposure The amount of light falling on the sensor
      • Proper exposure is critical for image quality
      • Determined by:
        • Brightness of the scene
        • Quality of the sensor
        • Shutter speed (ISO)
        • Aperture
  • 31. Digital Camera Basics: Capture
    • Bracketing
      • Taking several shots of the same subject using different or the same camera settings
      • Typically used when lighting is challenging or there is lots of movement
    125th/sec @ F8 – correct exposure 60th/sec @ F8 – overexposed 1 stop 250th/se @F8 – underexposed 1 stop
  • 32. Digital Camera Basics: Capture
    • Backgrounds
      • Plain, non-reflective surface keeps focus on subject
      • Try several different colors or textures
        • Neutral colors typically work best
        • Smooth out unnecessary folds
        • Cloth, table surface, foam core, etc.
  • 33. Digital Camera Basics: Capture
      • Papers, maps, and photos (“flat” material)
      • Soft, even light across entire surface. No glares or light spots
    • Two-dimensional objects
    http://uwdc.library.wisc.edu http://www.dkimages.com/discover/previews/805/450713.JPG
  • 34. Digital Camera Basics: Capture
      • Avoid keystoning, or distortion: photograph from a central point directly above (if laid horizontally) or parallel (if vertically)
      • Resolution: sufficient that the digital surrogate can be reproduced at the same or larger size as original
    • Two-dimensional objects
  • 35. Digital Camera Basics: Capture
    • Three-dimensional objects
      • Household items, sculpture, clothing, tools
      • Avoid light spots or extreme shadows
      • Get close
      • Consider taking more than one photograph (e.g., full & detail)
      • Shoot in the shade or on a cloudy day to take advantage of soft lighting and to show more detail
      • Expect to experiment, and that means time!
    http://digicoll.library.wisc.edu/Arts/
  • 36. Digital Camera Basics: Environment
    • Camera. Check. What else do you need?
      • Lights
      • Physical space
      • Accessories
        • Ladder, table, tripod
        • Gloves, object stands
        • Computer storage – or direct computer connection
        • Others?
  • 37. Digital Camera Basics: Environment
    • Physical space recommendations
      • Dedicated
      • Appropriate and adequate lighting
      • Adequate physical space to capture your objects
        • A large object will require a greater amount of space for capture
      • Quiet and clean
      • Ideally, the walls and floors are neutral colors and low reflection
      • Storage for accessories when not in use
  • 38. Digital Camera Basics: Costs
    • Digital Camera
        • 10 Megapixel P&S => $300
        • 10 Megapixel SLR => $900
        • Scan-back systems => $25,000+
    • Lenses
        • $100+
    • Lights
        • 2-light “economy” kits start at $150
    • Tripod
        • $25-$300
  • 39. Digital Camera Basics: Costs
    • The top-rated 8 MP (and up) semi-pro SLR cameras reviewed by CNET staff as of 10/8/2007 were
    • Nikon’s D200 and
    • Canon’s EOS 20D.
    • They cost between $800 and $2000.