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Basics Of Digital Photography

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Basics Of Digital Photography

  1. 1. The Basics of Digital Photography Ken Smith [email_address] www.quietheart.com
  2. 2. Objectives <ul><li>Understand the “Exposure Triangle” - how your camera uses aperture, shutter speed, and ISO setting to calculate exposure </li></ul><ul><li>Set aperture, shutter speed and ISO yourself given a particular photographic situation </li></ul><ul><li>Use your histogram to ensure good exposure </li></ul><ul><li>Learn what White Balance is and how to set it yourself </li></ul><ul><li>Apply the techniques of good composition </li></ul>
  3. 3. Promise and Pitfalls of Digital Imaging <ul><li>Digital imaging and image editing software like Photoshop allows you to perform everything from minor fixes to minor miracles, but… </li></ul><ul><li>Some mistakes can’t be fixed </li></ul><ul><li>Who wants to spend more time behind a computer? </li></ul><ul><li>The more care you take behind the camera , the less time you have to spend behind the computer , and the more great images you’ll make </li></ul>
  4. 4. What Is “Exposure”? <ul><li>Defined as the amount of light allowed to act on a photographic medium (digital sensor or film) </li></ul><ul><li>Most objects in the world (trees, rocks, sky, people) reflect back an average of 18% of the light that falls on them </li></ul><ul><li>Your camera takes a light meter reading and attempts to render everything it sees as 18% gray </li></ul><ul><li>This standard is known as “proper exposure” </li></ul><ul><li>All cameras and manufacturers use this standard </li></ul><ul><li>1/125 at f/16 at ISO 100 gives the same exposure whether you’re using a Canon, Nikon, Sony, or any other brand </li></ul>
  5. 5. The Exposure Triangle Exposure Aperture Shutter Speed ISO Setting
  6. 6. ISO Setting <ul><li>The base of the Exposure Triangle </li></ul><ul><li>Directly influences available apertures and shutter speeds </li></ul><ul><li>Generally not changed as often as aperture and shutter speed </li></ul>ISO Setting
  7. 7. What ISO Numbers Mean <ul><li>A holdover from film ratings </li></ul><ul><li>Lower ISO settings (50, 64, 100, 200) gather less light over a given interval of time </li></ul><ul><li>Higher ISO settings (400, 800, 1600) gather more light over a given interval of time </li></ul><ul><li>Each ISO setting represents a doubling of the amount of light gathered. ISO 200 gathers twice as much light as ISO 100, ISO 400 gathers 4x as much </li></ul>
  8. 8. Relationship to Aperture & Shutter Speed <ul><li>Keeping your aperture constant, a 1/30 second exposure at ISO 100 would require only 1/60 of a second (half the time) at ISO 200 </li></ul><ul><li>Keeping your shutter speed constant, an exposure requiring an aperture setting of f/4 at ISO 100 would require a setting of f/5.6 (letting in half the light) at ISO 200 </li></ul>
  9. 9. Which ISO Setting to Use? <ul><li>Use lower ISO (100, 200) settings in bright light (outdoors), or when freezing action is not necessary </li></ul><ul><li>Use higher ISO settings (400, 800, 1600) in low light or to freeze action in bright light </li></ul><ul><li>ISO 800 and 1600 can be used to shoot indoors without flash </li></ul>
  10. 10. Use Lowest ISO Setting Possible <ul><li>Higher ISO settings will increase “digital noise” </li></ul><ul><li>Problem is especially bad with smaller sensors </li></ul><ul><li>May not be noticeable in 4x6 snapshots, but will be very noticeable if you want to make an enlargement </li></ul><ul><li>Software can reduce noise, but the image will not be as sharp and detailed </li></ul><ul><li>Point and shoot and other digital cameras default to lowest possible ISO in automatic (program) mode </li></ul>
  11. 11. Very Low Noise at ISO 100 at 100% magnification
  12. 12. Digital Noise at ISO 800 at 100% magnification
  13. 13. Larger Sensors Can Reduce Noise (ISO 800) at 100% magnification
  14. 14. Aperture <ul><li>Controls amount of light gathered by the sensor </li></ul><ul><li>Also can be used creatively to control Depth of Field or Zone of Sharpness </li></ul>Aperture
  15. 15. Aperture Expressed as F-Stops <ul><li>An F-stop is the ratio of the aperture diameter of a lens to its focal length (f = Aperture/Focal Length) </li></ul><ul><li>A 50mm lens at f/4 has an opening of 12.5 mm (12.5/50 = ¼) </li></ul><ul><li>A 50mm lens at f/22 has an opening of 2.27 mm (2.27/50 = 1/22) </li></ul><ul><li>This is why F-stop numbers get BIGGER as the aperture gets smaller </li></ul>
  16. 16. What Do Those F-Stop Numbers Mean? <ul><li>Each standard F-Stop number represents a halving or doubling of the size of the aperture, thus halving or doubling the amount of light allowed to enter </li></ul><ul><li>The standard F-stop scale is f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 </li></ul><ul><li>Most digital cameras now offer increments of one half or one third of a stop for more precise exposure: f/2.8, f/3.2, f/3.5, f/4, f/4.5, f/5, f/5.6, etc. </li></ul>
  17. 17. Why Change Your Aperture? <ul><li>The size of your aperture doesn’t just control the amount of light entering – it also determines the range of distances that are in sharp focus </li></ul><ul><li>This range of distances is called Depth of Field or Zone of Sharpness </li></ul><ul><li>Modifying Zone of Sharpness gives you creative control over how much of the scene is in focus </li></ul><ul><li>Most pros shoot in Aperture Priority mode – they pick the aperture and the camera selects the shutter speed </li></ul>
  18. 18. Shallow Zone of Sharpness <ul><li>Wide apertures (f/2, f/2.8, f/4) generally provide shallow zone of sharpness </li></ul><ul><li>Less of the area in front of and behind your subject is in focus </li></ul><ul><li>Use wide apertures for shallow zone of sharpness when you want your subject to stand out from the background </li></ul><ul><li>Use when shooting portraits </li></ul>
  19. 19. Deeper Zone of Sharpness <ul><li>Smaller apertures (f/8, f/11, f/16, f/22) generally provide deeper zone of sharpness </li></ul><ul><li>More of the area in front of and behind your subject is in focus </li></ul><ul><li>Use smaller apertures for deeper zone of sharpness for landscapes or scenes where you want most of the scene in sharp focus </li></ul>
  20. 20. Other Factors Influencing Zone of Sharpness <ul><li>Wide angle lenses (or zoom lenses at their wider range) provide deeper zone of sharpness </li></ul><ul><li>Telephoto lenses (or zoom lenses at their telephoto range) tend to provide a more shallow zone of sharpness </li></ul><ul><li>The further away your subject is, the greater your zone of sharpness. A subject 20 feet away will generally have a greater zone of sharpness than a subject 3 feet away </li></ul>
  21. 21. Shutter Speed <ul><li>The final component of exposure </li></ul><ul><li>Shutter speed determines how long the sensor is exposed to the light coming off of your subject </li></ul><ul><li>Allows creative control by stopping or blurring motion </li></ul>Shutter Speed
  22. 22. Shutter Speed Ranges <ul><li>Most digital cameras (even point and shoot models) feature shutter speeds from 1 / 2000 of a second (or faster) to 30 seconds </li></ul><ul><li>Like ISO numbers and F-stops, each standard shutter speed (1/15, 1/30, 1/60, 1/125, 1/250, etc) represents a halving or doubling of the time the shutter is open </li></ul><ul><li>Like F-stops, most digital cameras now offer shutter speed increments of one half or one third of a stop (1/15, 1/20, 1/25, 1/30, 1/40, 1/50, 1/60, etc.) </li></ul>
  23. 23. Holding it Steady <ul><li>Hand-holding (least stable) </li></ul><ul><li>Image Stabilizing (IS) technology (more stable) </li></ul><ul><li>Tripod (most stable) </li></ul><ul><li>Hand hold your camera if your shutter speed is faster than the reciprocal of your focal length </li></ul><ul><li>For 50mm, handhold up to 1/50 second; for 200mm (telephoto), up to 1/200 second; for 28mm (wide angle), up to 1/30 second </li></ul><ul><li>Most digital cameras warn you when shutter speed is too long to hand hold without blurring </li></ul>
  24. 24. Image Stabilization <ul><li>Many cameras and lenses now feature technology to counteract the natural shake of the human hand (Image Stabilization, Anti-Shake, Vibration Reduction are some of the names manufactures use for this technology) </li></ul><ul><li>This technology will allow you to take longer exposures while still hand holding </li></ul><ul><li>Best bet in low light is a tripod (turn off IS) </li></ul><ul><li>For the ultimate in stability, use your 10 second self timer to allow the vibration of the tripod to die down before you shoot. Use this for really long exposures </li></ul>
  25. 25. Building the Exposure Triangle <ul><li>ISO Setting, Aperture and Shutter Speed work together to create proper exposure </li></ul><ul><li>Changing any one of these elements requires a change to at least one other element to maintain proper exposure </li></ul>Exposure Aperture Shutter Speed ISO Setting
  26. 26. Varying the Exposure Triangle <ul><li>The same scene with the same lighting can be shot many different ways </li></ul><ul><ul><li>At 1/125 sec at f/8 at ISO 100 </li></ul></ul><ul><ul><li>At 1/15 sec at f/22 at ISO 100 (greater zone of sharpness) </li></ul></ul><ul><ul><li>At 1/1000 sec at f/2.8 at ISO 100 (freeze fast action) </li></ul></ul><ul><ul><li>At 1/1000 sec at f/8 at ISO 800 (freeze action, greater zone of sharpness) </li></ul></ul><ul><ul><li>All depends on your goal in photographing that scene </li></ul></ul>
  27. 27. Get Beyond Program (P) Mode! <ul><li>Shoot in Aperture Priority – you select the aperture, the camera calculates the correct shutter speed </li></ul><ul><li>Use this to control depth of field </li></ul><ul><li>Shoot in Shutter Priority – you pick a shutter speed, the camera selects the correct aperture </li></ul><ul><li>Use when freezing or blurring motion is your main concern </li></ul><ul><li>Use shutter priority to pick a shutter speed fast enough for hand-holding </li></ul>
  28. 28. Scene Modes <ul><li>If you can’t control aperture or shutter speed directly, most point and shoot cameras offer scene modes (also available on advanced cameras and even SLRs) </li></ul><ul><li>Scene modes optimize the three factors of the Exposure Triangle – aperture, shutter speed, and ISO – for a particular shooting situation </li></ul>
  29. 29. Portrait Mode <ul><li>Selects wide aperture to minimize zone of sharpness </li></ul><ul><li>Makes sharp subject stand out from blurred background </li></ul><ul><li>Works best on single subject (person, pet, flower, etc.) </li></ul>
  30. 30. Macro Mode <ul><li>Adjusts focusing distance and lets you move closer into your subject </li></ul><ul><li>Generally wide aperture for narrow zone of sharpness </li></ul>
  31. 31. Landscape Mode <ul><li>Opposite of Portrait mode, selects small aperture for wide zone of sharpness </li></ul><ul><li>Use for wide scenes with more than one point of interest at different distances </li></ul>
  32. 32. Sports/Action Mode <ul><li>Selects faster shutter speeds to freeze action </li></ul><ul><li>Usually selects wider apertures and higher ISO to compensate for faster shutter speed </li></ul><ul><li>Use any time you have a moving subject </li></ul>
  33. 33. Night Mode <ul><li>Uses a combination of flash and slow shutter speed to equally expose subject and background </li></ul><ul><li>Use a tripod for a sharp background </li></ul><ul><li>Hand-holding can lead to some creative effects </li></ul>
  34. 34. Histograms <ul><li>Histograms can help ensure you’ve achieved a good exposure </li></ul><ul><li>Histograms show the relative distribution of dark and light tones throughout an image </li></ul><ul><li>A well-exposed scene generally shows a smooth distribution of tones without bunching up toward the dark end or light end of the scale </li></ul>
  35. 35. Well-Exposed Image
  36. 36. Over-Exposed Image <ul><li>Indicating by clipping on right end of histogram (highlights) </li></ul><ul><li>Detail in highlights has been lost; highlights are “blown out” </li></ul><ul><li>You can adjust overall brightness and contrast in your image editing software, but you can’t put back missing detail </li></ul>
  37. 37. Over-Exposed Image
  38. 38. Under Exposed Image <ul><li>Indicated by clipping at left end of histogram (shadows) </li></ul><ul><li>Detail in shadows has been lost; shadows are “blocked up” </li></ul><ul><li>Again, you can make the image brighter in your image editing software, but you can’t put back missing shadow detail </li></ul>
  39. 39. Under-Exposed Image
  40. 40. Fixing Exposure Problems <ul><li>Use your camera’s Automatic Exposure Lock (AE) button: </li></ul><ul><ul><li>Focus on a lighter or darker portion of the scene (depending on whether your problem is under-exposure or over-exposure) </li></ul></ul><ul><ul><li>Depress your shutter halfway or press the Automatic Exposure Lock (AE) button to lock exposure </li></ul></ul><ul><ul><li>Recompose image and fire </li></ul></ul>
  41. 41. Fixing Exposure Problems, continued <ul><li>Use your camera’s Exposure Compensation control </li></ul><ul><li>Sometimes indicated as AV or EV button or dial </li></ul><ul><li>Allows you to vary exposure usually by +/- 2 stops from what camera indicates in one third stop increments </li></ul>
  42. 42. Hard to Expose Scenes <ul><li>High contrast scenes with dark shadows and bright highlights may be difficult for your camera to capture accurately </li></ul><ul><li>The dynamic range of the human eye is about 17 stops or 250,000 to 1 </li></ul><ul><li>High end digital cameras can only record a dynamic range of up to 10 stops or 1,000 to 1 </li></ul><ul><li>Digital cameras can’t “see” the same dynamic range we do </li></ul>
  43. 43. Handling High Contrast Scenes <ul><li>Recompose to minimize the bright highlights or deep shadows </li></ul><ul><li>Use your flash to even out the illumination and fill in the shadows </li></ul><ul><li>Shoot in RAW mode (which captures widest dynamic range) process for shadows and then for highlights, and combine both versions in your image editing software </li></ul><ul><li>Shoot two exposures (use a tripod) – one for shadows, one for highlights - and combine using your image editing software </li></ul>
  44. 44. Light Has a Color Temperature <ul><li>The color temperature of light is expressed in degrees Kelvin (K) </li></ul><ul><li>Light under shade and clouds tends to be blue </li></ul><ul><li>Sunlight & Flash are nearly pure white </li></ul><ul><li>Incandescent light and the light at sunrise & sunset tends to be orange </li></ul>
  45. 45. White Balance <ul><li>Your camera’s white balance compensates for the light’s color temperature by shifting all colors in the opposite direction </li></ul><ul><li>Auto White Balance (AWB) does a good job, but your camera’s presets give more natural results </li></ul><ul><li>AWB neutralizes the color temperature of the ambient light and can lead to dull color </li></ul><ul><li>Presets usually include sunlight, shade, cloudy, tungsten (incandescent) and florescent </li></ul>
  46. 46. White Balance, continued <ul><li>Many cameras give you the ability to set a custom white balance, but you’ll probably never have to </li></ul><ul><li>NEVER use AWB when shooting a sunrise or sunset if you want to preserve the rich color </li></ul><ul><li>Scene modes in point and shoots often set WB. Some models include a Sunset mode to preserve the color </li></ul><ul><li>Experiment with special effects by using the “wrong” presets (e.g., shooting a snow scene in incandescent mode to make the snow a cool blue) </li></ul>
  47. 47. Image File Formats <ul><li>Most cameras give two options – RAW and JPEG </li></ul><ul><li>Some also offer TIFF format </li></ul><ul><li>New format called DNG (Digital Negative) </li></ul><ul><li>Which format to use depends on: </li></ul><ul><ul><li>How much processing you want to do to the image </li></ul></ul><ul><ul><li>Which software you use to edit your images </li></ul></ul><ul><ul><li>How much storage space you have in your memory card </li></ul></ul>
  48. 48. JPEG Format <ul><li>Camera software converts raw data, making color and exposure decisions </li></ul><ul><li>Smaller files – you can fit more on your memory card </li></ul><ul><li>Format recognized by many different programs and can be easily distributed </li></ul><ul><li>Compression is “lossy” – data is permanently removed when a JPEG is saved and resaved </li></ul>
  49. 49. RAW Format <ul><li>Like a digital “negative” RAW files contain maximum amount of data. You can change exposure settings and white balance after taking the shot </li></ul><ul><li>Requires proprietary software or a plug-in to process (though newer software supports RAW) </li></ul><ul><li>Larger than JPEG – you can’t fit as many on a memory card </li></ul><ul><li>Must be converted to JPEG or another format before you can distribute </li></ul>
  50. 50. RAW + JPEG Mode <ul><li>Many cameras now offer the option to shoot a RAW file and JPEG at the same time </li></ul><ul><li>This gives you the convenience of a JPEG but with all the data of the RAW file should you need to adjust exposure and white balance </li></ul><ul><li>Takes up more room, but memory cards have gotten inexpensive (2 GB sell for under $50) </li></ul>
  51. 51. Digital Negative (DNG) <ul><li>Problem with RAW format is that it is proprietary to that manufacturer and that particular camera model </li></ul><ul><li>Concern is that a particular RAW format may not be readable by software in a few years or decades </li></ul><ul><li>Adobe’s Digital Negative (DNG) format is designed to contain all of the data of a RAW file, but in a format that will be universally readable in the future (like JPEG) </li></ul>
  52. 52. Image Editing Software <ul><li>Adobe Photoshop CS3 </li></ul><ul><ul><li>Industry standard, has every feature you need </li></ul></ul><ul><ul><li>Very expensive ($600 street price), but worth it! </li></ul></ul><ul><ul><li>Steep learning curve </li></ul></ul><ul><li>Photoshop Elements </li></ul><ul><ul><li>Gives you the most used features of Photoshop CS3 (levels, curves, color balance) </li></ul></ul><ul><ul><li>Much less expensive (under $100) – sometimes bundled free </li></ul></ul><ul><ul><li>Easier for beginners than CS3 </li></ul></ul>
  53. 53. Image Editing Software, continued <ul><li>Corel Paint Shop Pro </li></ul><ul><ul><li>Inexpensive (about $100), but packed with features </li></ul></ul><ul><ul><li>Easy to use </li></ul></ul><ul><ul><li>Runs on Windows only </li></ul></ul><ul><li>Picasa </li></ul><ul><ul><li>Free from Google </li></ul></ul><ul><ul><li>Offers very basic editing (red-eye fix, color, contrast, some special effects) </li></ul></ul><ul><ul><li>A very powerful organizing tool </li></ul></ul>
  54. 54. Software Resources <ul><li>Picasa: http:// picasa.google.com/index.html </li></ul><ul><li>Adobe: http://www.adobe.com </li></ul><ul><li>Corel: http://www.corel.com </li></ul>
  55. 55. Saving and Storing Your Files <ul><li>Best to save in the native format of your image editing software </li></ul><ul><li>Don’t keep resaving as a JPEG. Each time you save, some of your data will be permanently discarded </li></ul><ul><li>Keep your RAW or untouched originals separate in case you need to start all over again </li></ul>
  56. 56. Sharing & Printing Photos Online <ul><li>Many companies offer online photo albums and allow you to share your photos with others </li></ul><ul><li>Most are free, but for a small fee you can usually purchase more storage </li></ul><ul><li>Generally accept JPEG or GIF formats only </li></ul><ul><li>You can also order prints, posters, calendars, etc. </li></ul><ul><li>Size of file uploaded determines size of print you can order </li></ul>
  57. 57. Some Photo Sharing & Printing Websites <ul><li>Flikr ( http:// www.flikr.com ) - Features social networking features </li></ul><ul><li>DotPhoto ( http:// www.dotphoto.com ) – Good print quality, allows albums to be shared </li></ul><ul><li>Shutterfly ( http:// www.shutterfly.com ) - voted best by PC magazine </li></ul><ul><li>Mpix ( http:// www.mpix.com ) – Excellent print quality, but no way to share photos </li></ul>
  58. 58. Photo Printers <ul><li>You can print professional quality photos at home </li></ul><ul><li>Some feature 6, 7, or 8 color inks (Canon just introduced a 10 color pro printer). More inks means a greater range of colors that can be reproduced </li></ul><ul><li>Epson pioneered archival inks – now HP and Canon also offer archival printers </li></ul><ul><li>Some printers designed for black & white </li></ul><ul><li>You can print up to 12x18 prints on a variety of papers – gloss, luster, matte, watercolor, etc. </li></ul>
  59. 59. Printer Manufacturers <ul><li>Epson ( www.epson.com ) </li></ul><ul><ul><li>Geared primarily to pro market, but now make easy to use consumer printers </li></ul></ul><ul><ul><li>Most large format print labs use Epson printers </li></ul></ul><ul><li>HP ( www.hp.com ) </li></ul><ul><ul><li>Known for easy-to-use consumer printers, but now make excellent pro printers </li></ul></ul><ul><ul><li>Some print directly from your camera’s memory card </li></ul></ul><ul><li>Canon ( http:// www.usa.canon.com ) </li></ul><ul><ul><li>New pro line of printers </li></ul></ul>
  60. 60. Composing the Image <ul><li>Photography is not just about equipment, it is ultimately an aesthetic pursuit </li></ul><ul><li>Photography tells a story, expresses a mood, lets us express ourselves </li></ul><ul><li>Why do some photos have impact and other don’t? </li></ul>
  61. 61. Composition as Visual Language <ul><li>Photography, like other arts, is a universal language </li></ul><ul><li>As with any language, there are techniques that allow you to communicate more clearly </li></ul>
  62. 62. Technique 1: Get Closer <ul><li>Your viewer should have no question about what the subject of your photo is </li></ul><ul><li>Don’t be afraid to fill the frame with your subject </li></ul><ul><li>Ask yourself “What is drawing me to take this photo?” Then, photograph THAT! </li></ul><ul><li>Photographers are editors of reality </li></ul>
  63. 63. Technique 2: Use the “Rule of Thirds” <ul><li>Placing your subject dead enter in your frame is static and boring </li></ul><ul><li>One way to create interest is to use the Rule of Thirds </li></ul><ul><li>Use for subject placement as well as line placement (horizons) </li></ul>
  64. 64. Take your viewfinder and visualize it divided into thirds
  65. 65. The main subject of your image should appear at the intersection of those grid lines
  66. 66. The main subject of your image should appear at the intersection of those grid lines
  67. 67. In a close-up (macro), the most visually interesting part should lie near an intersection
  68. 68. Use the horizontal lines to place your horizon
  69. 69. Technique 3: Use Diagonals <ul><li>Another way to create a dynamic composition is to use diagonal lines </li></ul><ul><li>Diagonal lines create movement and flow in your image </li></ul>
  70. 70. Technique 4: Use Leading Lines <ul><li>Leading lines can lead the viewer into your photo </li></ul><ul><li>Use roads, paths, streams, or other patterns as leading lines. Edges or rows of objects can also function as leading lines </li></ul>
  71. 71. Technique 5: Frame Your Subject <ul><li>Framing your subject with foreground elements creates compositions with depth </li></ul><ul><li>The frame can go all the way around or appear only on 2 or 3 sides </li></ul><ul><li>Be sure your zone of sharpness allows both your frame and your subject to be in sharp focus </li></ul>
  72. 72. Technique 6: Balance Main Subject with a Secondary Subject <ul><li>You can have more than one subject in a photo </li></ul><ul><li>Make a visual distinction, such as size or placement, indicating which is the main subject and which is secondary </li></ul><ul><li>Use rule of thirds when placing both subjects in the frame </li></ul>
  73. 73. Wrap-Up <ul><li>Questions? </li></ul><ul><li>For follow-up questions, email: [email_address] </li></ul>

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