Digital Photography I

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Presentation on digital photography I gave in 2005 at the Saratoga Library.


<ul><li>Digital Photography I The Basics Peter Liu Photography kaiscapes .com </li><li>Photography <ul><li>From two Greek words meaning drawing with light: </li></ul><ul><li><ul><li> phos ("light") </li></ul></li></ul><ul><li><ul><li> graphis ("stylus", "paintbrush") </li></ul></li></ul><ul><li>Merriam-Webster: </li></ul><ul><li> The art or process of producing images on a sensitized surface (as a film) by the action of radiant energy and especially light. </li></ul></li><li>Photography <ul><li> 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. </li></ul></li><li>Capturing Light <ul><li>Hard Light high contrast, well-defined shadows </li></ul></li><li>Capturing Light <ul><li>Soft Light diffused, rich colors </li></ul></li><li>Capturing Light <ul><li>Overhead Light harsh shadows </li></ul></li><li>Capturing Light <ul><li>Front Light flat, lacks dimension </li></ul></li><li>Capturing Light <ul><li>Side Light evokes mood, accentuates shapes </li></ul></li><li>Capturing Light <ul><li>Back Light may need to fill, makes silhouettes </li></ul></li><li>Capturing Light <ul><li>Overcast Light low contrast, muted shadows, good for detail </li></ul></li><li>Characteristics Of Light <ul><li>Quality </li></ul><ul><li><ul><li>The smaller the light source, the harder the light appears </li></ul></li></ul><ul><li><ul><li>The larger the light source, the softer the light appears </li></ul></li></ul><ul><li>Direction </li></ul><ul><li><ul><li>Determines where shadows fall </li></ul></li></ul><ul><li>Contrast </li></ul><ul><li><ul><li>Difference between the lightest and darkest tones of the subject or image </li></ul></li></ul><ul><li>Source </li></ul><ul><li>Ambient daylight, tungsten, flourescent, firelight </li></ul><ul><li>Artificial flash, tungsten </li></ul><ul><li>Intensity </li></ul><ul><li>Reflectance </li></ul><ul><li><ul><li>Reflectivity of the subject </li></ul></li></ul><ul><li><ul><li>Intensity of the light source </li></ul></li></ul><ul><li><ul><li>Angle of view </li></ul></li></ul><ul><li><ul><li>Distance of light source </li></ul></li></ul><ul><li>Fall-off </li></ul><ul><li><ul><li>Increase distance, decrease light level (Inverse Square Law) </li></ul></li></ul></li><li>Characteristics Of Light <ul><li>Color </li></ul><ul><li>Mixture of primary colors: Red, Green and Blue varies according to source </li></ul><ul><li> Warm predominantly red </li></ul><ul><li> Cool predominantly blue </li></ul><ul><li>Expressed in Kelvin (K): </li></ul><ul><li><ul><li>Incandescent ~ 3000K </li></ul></li></ul><ul><li><ul><li>Fluorescent ~ 4100K </li></ul></li></ul><ul><li><ul><li>Flash ~ 5400K </li></ul></li></ul><ul><li><ul><li>Daylight </li></ul></li></ul><ul><li><ul><li><ul><li>Direct Sunlight ~ 5200K </li></ul></li></ul></li></ul><ul><li><ul><li><ul><li>Cloudy ~ 6000K </li></ul></li></ul></li></ul><ul><li><ul><li><ul><li>Shade ~ 8000K </li></ul></li></ul></li></ul><ul><li>Referred to as White Balance in digital photography. </li></ul></li><li>White Balance 4100K ( Fluorescent ) 3000K ( Incandescent ) 5200K ( Sunlight ) 8000K ( Shade ) 5400K ( Flash ) 6000K ( Cloudy ) </li><li>Why Are You Telling Us All This?? <ul><li>Because good photography depends on being able to execute two things well: </li></ul><ul><li>Exposure </li></ul><ul><li>Composition </li></ul></li><li>Exposure <ul><li>A combination of three factors sometimes known as the Photographic Triangle: </li></ul><ul><li>Shutter Speed </li></ul><ul><li>Aperture </li></ul><ul><li>ISO </li></ul><ul><li>Or </li></ul><ul><li>how quickly light is being captured through how big an opening onto how sensitive a surface </li></ul></li><li>Shutter <ul><li>A cameras shutter covers the hole through which light enters to expose the sensor or film. </li></ul>The shutter release button causes the shutter to open for a certain amount of time, then close again. Image source: www. howstuffworks .com Image source: VisibleDust </li><li>Shutter Speed Fast <ul><li>1/1600 sec., stops action </li></ul></li><li>Shutter Speed Slow <ul><li>Silky, cool, edgy effects </li></ul>1 sec. 3 sec. 1/3 sec. </li><li>Shutter Speeds <ul><li>Open too long, photos are washed out (overexposed) </li></ul><ul><li>Not long enough, photos are too dark (underexposed) </li></ul><ul><li>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. </li></ul><ul><li>Each setting is half or double the speed of its neighbor. </li></ul><ul><li>As the amount of available light decreases by half, the shutter speed needs to slow by double. </li></ul><ul><li>As the amount of available light increases, the shutter speed needs to increase </li></ul></li><li>Aperture <ul><li>The opening through which light enters the camera. </li></ul>Sometimes called an iris because it imitates the opening in the human eye. Image source: </li><li>Aperture <ul><li>The size of the opening is expressed as an f-stop number : </li></ul><ul><li>Each number represents an opening size that is half or double its neighbor </li></ul><ul><li>The larger the number, the smaller the opening </li></ul><ul><li>For 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: </li></ul><ul><li><ul><li>e.g. f/2 on a 50mm lens says the aperture is 25mm. 50/25 = 2. </li></ul></li></ul><ul><li><ul><li>(Source: A Tedious Explanation of the f/stop by Matthew Cole) </li></ul></li></ul><ul><li>For the rest of us: the size of the opening controls the depth of field in the photograph. </li></ul></li><li>Aperture And Depth Of Field <ul><li>f/5.6 </li></ul><ul><li>Shallow depth of field </li></ul>f/22 Deep depth of field </li><li>Aperture And Depth Of Field <ul><li>Caused by refraction of the light hitting the edge of the opening </li></ul><ul><li>Rays scatter and overlap instead of going straight on its way to the sensor or film </li></ul><ul><li>The camera sees multiple images, resulting in blur. </li></ul><ul><li>The smaller the opening, the less surface available to scatter the light, resulting in less blur. </li></ul><ul><li>Bottom line: the aperture is used to control how much of the scene is in focus. </li></ul></li><li>Aperture And Shutter Speed <ul><li>The following reciprocals will yield the same exposure: </li></ul><ul><li>What changes is how much is sharp and in focus. </li></ul>1/8 sec. f/22 1/15 sec. f/16 1/30 sec. f/11 1/60 sec. f/8 1/125 sec. f/5.6 1/250 sec. f/4 1/500 sec. f/2.8 </li><li>The Light Meter <ul><li>A device that assesses a scene and figures out the correct exposure </li></ul><ul><li>Modern cameras have them built-in </li></ul><ul><li>External handheld models also available </li></ul><ul><li>Engaged when shutter is pressed halfway </li></ul><ul><li>Matrix/Evaluative, Center-weighted, Spot metering </li></ul><ul><li>Looks for 18% Grey or Middle Grey </li></ul><ul><li>Easily fooled! </li></ul></li><li>Tricky Metering Situations </li><li>Exposure Compensation <ul><li>Used when the light meter is unable to evaluate the exposure as desired, or when correcting by whole stops is too much </li></ul><ul><li>Usually +/- 2 EV (Exposure Value) in steps of 0.3 EV </li></ul><ul><li>Available on most cameras </li></ul></li><li>ISO <ul><li>Sensitivity of the sensor or film to light </li></ul><ul><li>Represented by a number assigned by the International Standards Organization (hence, ISO) 100, 200, 400, 800, etc. </li></ul><ul><li>Again, each number represents double or half the sensitivity of its neighbor (Aint it wonderful!) </li></ul><ul><li>The higher the number, the more sensitive to light </li></ul><ul><li>Digital photography is cool because you can change the ISO from shot to shot! </li></ul></li><li>Higher ISO = More Noise! <ul><li>ISO 3200 </li></ul></li><li>So <ul><li>Exposure depends on: </li></ul><ul><li>Shutter Speed how fast </li></ul><ul><li>Aperture how much </li></ul><ul><li>ISO how sensitive </li></ul><ul><li>And color is a function of: </li></ul><ul><li>White Balance how hot </li></ul></li><li>And <ul><li>Which camera you choose is a function of how much you want control those factors! </li></ul></li><li>Cameras <ul><li>Two popular types of cameras on the market for the consumer </li></ul>Point-and-shoot SLR (Single-lens Reflex) </li><li>Cameras <ul><li>Point-and-shoot </li></ul><ul><li>Viewfinder separate from lens </li></ul><ul><li>Small and compact </li></ul><ul><li>Fixed lens </li></ul><ul><li>Shutter delay </li></ul><ul><li>Usually fully automatic (some exceptions, like Olympus C-series) </li></ul><ul><li>SLR (Single-lens Reflex) </li></ul><ul><li>Based on 35mm design </li></ul><ul><li>Actual image seen in viewfinder </li></ul><ul><li>Interchangeable lenses (more flexible composition) </li></ul><ul><li>Ability to use filters </li></ul><ul><li>More advanced metering and shutter system </li></ul><ul><li>Little to no shutter delay </li></ul><ul><li>Automatic, Program (Scene), Shutter Priority, Aperture Priority and Manual modes </li></ul><ul><li>Flash hot shoe </li></ul><ul><li>Pro models may not have pop-up flash or Program (scene) modes </li></ul></li><li>Point-and-shoot Anatomy <ul><li>Viewfinder separate from lens (better to use LCD on digital) </li></ul><ul><li>Actual image (as exposed) is not quite the same as in the viewfinder </li></ul><ul><li>Much simpler design than SLRs. </li></ul>Light Path Lens Camera Body Viewfinder (front) Shutter Sensor or Film Viewfinder Focal Length LCD Screen (Digital) </li><li>SLR Anatomy <ul><li>Through-the-lens (TTL) viewing (works like a periscope) </li></ul><ul><li>Actual image (as exposed) is shown in the viewfinder </li></ul><ul><li>Mirror flips up when the shutter release is pressed, exposing the sensor (and blacking out the viewfinder) </li></ul><ul><li> Reflex comes from the use of the mirrors in the viewfinder system. </li></ul>Light Path Lens Camera Body Focusing Screen Mirror (Pentaprism) Mirror (flips up) Shutter Sensor or Film Viewfinder Focal Length LCD Screen (Digital) </li><li>Advantages Of Digital <ul><li>Instant gratification (big fun factor) see your images right away </li></ul><ul><li>No film cost shoot as many as you want, erase and shoot again (heck, its just pixels!) </li></ul><ul><li>Convenience print, email, web, slide shows; no waiting around for the photos to come back from the store </li></ul><ul><li>Easier to make copies no need to send (or lose) originals </li></ul><ul><li>Easier to manipulate no scanning required (you did that when you pressed the shutter) </li></ul><ul><li>No need to spend hours in the darkroom </li></ul><ul><li>Black-and-white just shades of grey colors </li></ul><ul><li>No worries about film fading over time; digital images last for as long as your storage media doesnt die on you </li></ul><ul><li>Less storage space no physical shelves to keep stacking </li></ul><ul><li>Metadata information available for indexing and cataloging. </li></ul></li><li>Disadvantages Of Digital <ul><li>Image quality </li></ul><ul><li><ul><li>As good or better than 35mm in the right hands , but cannot compete with medium or large format film (yet) </li></ul></li></ul><ul><li><ul><li>1.5x cropping factor or focal length multiplier in SLRs due to smaller sensor </li></ul></li></ul><ul><li><ul><li>Exposure much more critical 1/3 stop subtle in Velvia, but blatant in digital </li></ul></li></ul><ul><li><ul><li>Blown highlights no information means no information; film is better at rendering overexposed areas more naturally </li></ul></li></ul><ul><li><ul><li>Great shadow detail, but clipped highlights -- traded highlight detail for lower noise; most likely need to underexpose and correct in post </li></ul></li></ul><ul><li><ul><li>Skilled user needed to extract the image quality equivalent to that of good film </li></ul></li></ul><ul><li>Very different workflow requires skill with computers and software, knowledge of color management and printing, web, email, etc. </li></ul><ul><li>You are the photo lab youve traded darkroom chemicals for a digital darkroom </li></ul><ul><li>Easy to lose images memory cards can become corrupted in-camera; photos are scattered all over your computer; hard drives die </li></ul><ul><li>Slow camera is locked up once the buffer is filled until the images are completely written to the card </li></ul><ul><li>Shutter delay (point-and-shoot) </li></ul><ul><li>Digicams are much more expensive than film cameras and become obsolete sooner </li></ul><ul><li>Slide shows projectors designed for business graphics render poor photographic quality and awful color. </li></ul><ul><li>More megapixels = bigger files = more storage + faster computers </li></ul></li><li>Which Is Better? <ul><li>The apple or the orange? </li></ul><ul><li>Each has their respective strengths and weaknesses. </li></ul><ul><li>It all depends on what youre trying to accomplish. </li></ul><ul><li>Everything in photography is a trade-off. </li></ul></li><li>Choosing A Digital Camera <ul><li>The number of megapixels isnt everything! </li></ul><ul><li>More is not necessarily better, </li></ul><ul><li>But more can be an advantage when cropping or printing big. </li></ul></li><li>Megapixel Madness </li><li>How Many Pixels Do You Need? <ul><li>Assume 300 dpi (dots per inch) for a good quality print on a desktop printer </li></ul><ul><li>Break down megapixels to length and width, then divide by 300 </li></ul><ul><li><ul><li>e.g. 6MP ~ 3008 x 2000 pixels (Nikon D70) </li></ul></li></ul><ul><li><ul><li> 3008/300 = 10.027 in. </li></ul></li></ul><ul><li><ul><li> 2000/300 = 6.667 in. </li></ul></li></ul><ul><li>BUT, different printers have different requirements </li></ul><ul><li>Software can help upsize or downsize with varying results </li></ul><ul><li>Large fudge factor, depending on chosen application and printer technology. </li></ul></li><li>Digital Camera Resolution Chart (Source: B&amp;H Photo-Video-Pro Audio ) </li><li>So, How Do I Choose A Camera? <ul><li>Ergonomics how does it feel in your hands? </li></ul><ul><li>Size and weight of the camera </li></ul><ul><li>Size and quality of the LCD </li></ul><ul><li>Lens quality </li></ul><ul><li><ul><li>Sharpness </li></ul></li></ul><ul><li><ul><li>Distortion </li></ul></li></ul><ul><li><ul><li>Zoom capability (optical vs. digital) </li></ul></li></ul><ul><li><ul><li><ul><li>Digital zoom is evil! </li></ul></li></ul></li></ul><ul><li>Metering capability </li></ul><ul><li>Built-in flash </li></ul><ul><li><ul><li>Red-eye reduction </li></ul></li></ul><ul><li><ul><li>Can you control it? </li></ul></li></ul><ul><li>Manual capability vs. automatic or program modes </li></ul><ul><li>Battery life </li></ul><ul><li>Media type </li></ul><ul><li>Decide whats important to you based on how youll be using it! </li></ul></li><li>About The Cards <ul><li>Pick One </li></ul>Compact Flash SD MiniSD xD MultiMediaCard RS-MMC (Reduced-Size MultiMediaCard) SmartMedia Memory Stick Image source: Lexar </li><li>I Bought A Camera Now What? <ul><li>Charge the battery </li></ul><ul><li>Format the card </li></ul><ul><li>Set up the camera </li></ul><ul><li><ul><li>Date and time </li></ul></li></ul><ul><li><ul><li>Bells and whistles (literally!) </li></ul></li></ul><ul><li><ul><li>Digital zoom if you can turn it off, do it! </li></ul></li></ul><ul><li><ul><li>Mode: Auto, Program, Aperture Priority, Shutter Priority, Manual </li></ul></li></ul><ul><li><ul><li>ISO </li></ul></li></ul><ul><li><ul><li>White balance </li></ul></li></ul><ul><li><ul><li>Color space (Never mind!) </li></ul></li></ul><ul><li><ul><li>Image quality and file type </li></ul></li></ul><ul><li><ul><li><ul><li>JPEG (Joint Photo Experts Group) in-camera processing, lossy (small, medium, large), 8-bits (256 shades of color) per channel (16.7 million colors) </li></ul></li></ul></li></ul><ul><li><ul><li><ul><li>TIFF (Tagged Image File Format) in-camera processing, uncompressed, lossless, 8-bits per channel </li></ul></li></ul></li></ul><ul><li><ul><li><ul><li>RAW direct output from the sensor, little to no in-camera processing, 12-bit (4096 shades of color) per channel (68.7 billion colors) </li></ul></li></ul></li></ul><ul><li>What are you waiting for?? Go shoot pictures! </li></ul></li><li>Recall <ul><li>Good photography depends on being able to execute two things well: </li></ul><ul><li>Exposure </li></ul><ul><li>Composition </li></ul></li><li>Composition <ul><li> The art of including the essence of what moves you about the scene in your photograph, while excluding any non-essential, distracting elements. </li></ul></li><li>Composition <ul><li>There are established guidelines, but ultimately, its about your artistic vision </li></ul><ul><li>Very subjective </li></ul><ul><li>Not always a conscious thing listen to your heart! </li></ul><ul><li>Simplify, Simplify, Simplify! </li></ul></li><li>Simplify </li><li>Simplify </li><li>Simplify </li><li>Simplify </li><li>Simplify </li><li>Simplify </li><li>Composition <ul><li> You take the picture, but you make the photograph. </li></ul><ul><li>Its about seeing the photograph in front of you. </li></ul><ul><li>Its about design arranging all the elements of the scene in your viewfinder so they become something compelling to look at. </li></ul><ul><li>Hold the viewers attention as their eyes travel around the frame. </li></ul><ul><li>Check your corners! Move your eye around the frame in the viewfinder looking for anything that might distract attention away from your subject(s) a stray branch, somebodys toe, etc. </li></ul><ul><li>Our eyes are naturally drawn to brighter, hotter elements. If those arent your subject(s), exclude them! </li></ul></li><li>Composition <ul><li>Do in in the viewfinder, not in Photoshop! Its always best to start with a good image. </li></ul><ul><li><ul><li> Photoshop doesnt make a bad photograph good, it makes a bad photograph big. </li></ul></li></ul><ul><li>Youre rendering a 3-D scene as a 2-D print. Frame it carefully! </li></ul><ul><li>Try not to bullseye your subject in the frame. Dead center is deadly! </li></ul><ul><li>Use the Rule Of Thirds the oldest trick in the book for composing a visually balanced and pleasing image. </li></ul></li><li>Rule Of Thirds <ul><li>Divide your scene into an imaginary tic-tac-toe grid, then place your subject(s) near any of the four intersections </li></ul></li><li>Use Those Lines! <ul><li>Diagonal lines are especially dynamic. Use them to lead the viewer to the subject, guide the viewer across the frame or create vanishing points. </li></ul></li><li>Find Grace <ul><li>The S-curve is a classic compositional device to create a sense of grace. </li></ul>Give moving subjects space to go. Dont place them so they are about to run off the frame. </li><li>Tips For Better Composition <ul><li>Try not to cut off any body parts. </li></ul><ul><li>Dont have trees or telephone poles growing out of your subjects heads. </li></ul></li><li>Tips For Better Composition <ul><li>Tell a story with your photographs </li></ul></li><li>Learn, Practice, Then Forget <ul><li>Remember, these are just guidelines, not hard and fast rules. </li></ul>Dont be afraid to experiment! Look for different viewpoints. Try tilting the camera. Try it blurry! You are only limited by your own creativity! </li><li>Now That You Have Your Pictures <ul><li>Time for the workflow </li></ul><ul><li>Why do you need a workflow? </li></ul><ul><li><ul><li>Because your photos are trapped in your card and somebody has to liberate them </li></ul></li></ul><ul><li><ul><li>Because its too expensive not to get them out and print/email/put-them-on-the-web yourself </li></ul></li></ul><ul><li><ul><li>Because you want artistic control over how your photos are displayed </li>