Digital Photography I
Presentation on digital photography I gave in 2005 at the Saratoga Library.
Digital Photography I The Basics Peter Liu Photography kaiscapes .com Photography From 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. 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. Capturing Light Hard Light high contrast, well-defined shadows Capturing Light Soft Light diffused, rich colors Capturing Light Overhead Light harsh shadows Capturing Light Front Light flat, lacks dimension Capturing Light Side Light evokes mood, accentuates shapes Capturing Light Back Light may need to fill, makes silhouettes Capturing Light Overcast Light low contrast, muted shadows, good for detail Characteristics Of Light Quality The smaller the light source, the harder the light appears The larger the light source, the softer the light appears Direction Determines where shadows fall Contrast Difference between the lightest and darkest tones of the subject or image Source Ambient daylight, tungsten, flourescent, firelight Artificial flash, tungsten Intensity Reflectance Reflectivity of the subject Intensity of the light source Angle of view Distance of light source Fall-off Increase distance, decrease light level (Inverse Square Law) Characteristics Of Light Color Mixture of primary colors: Red, Green and Blue varies according to source Warm predominantly red Cool predominantly blue Expressed in Kelvin (K): Incandescent ~ 3000K Fluorescent ~ 4100K Flash ~ 5400K Daylight Direct Sunlight ~ 5200K Cloudy ~ 6000K Shade ~ 8000K Referred to as White Balance in digital photography. White Balance 4100K ( Fluorescent ) 3000K ( Incandescent ) 5200K ( Sunlight ) 8000K ( Shade ) 5400K ( Flash ) 6000K ( Cloudy ) Why Are You Telling Us All This?? Because good photography depends on being able to execute two things well: Exposure Composition Exposure A combination of three factors sometimes known as the Photographic Triangle: Shutter Speed Aperture ISO Or how quickly light is being captured through how big an opening onto how sensitive a surface Shutter A 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 .com Image source: VisibleDust Shutter Speed Fast 1/1600 sec., stops action Shutter Speed Slow Silky, cool, edgy effects 1 sec. 3 sec. 1/3 sec. Shutter Speeds Open 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 Aperture The 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 Aperture The 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 neighbor The larger the number, the smaller the opening 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: 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. Aperture And Depth Of Field f/5.6 Shallow depth of field f/22 Deep depth of field Aperture And Depth Of Field Caused by refraction of the light hitting the edge of the opening Rays scatter and overlap instead of going straight on its way to the sensor or film The 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. Aperture And Shutter Speed The following reciprocals will yield the same exposure: What changes is how much is sharp and in focus. 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 The Light Meter A device that assesses a scene and figures out the correct exposure Modern cameras have them built-in External handheld models also available Engaged when shutter is pressed halfway Matrix/Evaluative, Center-weighted, Spot metering Looks for 18% Grey or Middle Grey Easily fooled! Tricky Metering Situations Exposure Compensation Used when the light meter is unable to evaluate the exposure as desired, or when correcting by whole stops is too much Usually +/- 2 EV (Exposure Value) in steps of 0.3 EV Available on most cameras ISO Sensitivity of the sensor or film to light Represented 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 light Digital photography is cool because you can change the ISO from shot to shot! Higher ISO = More Noise! ISO 3200 So Exposure depends on: Shutter Speed how fast Aperture how much ISO how sensitive And color is a function of: White Balance how hot And Which camera you choose is a function of how much you want control those factors! Cameras Two popular types of cameras on the market for the consumer Point-and-shoot SLR (Single-lens Reflex) Cameras Point-and-shoot Viewfinder separate from lens Small and compact Fixed lens Shutter delay Usually fully automatic (some exceptions, like Olympus C-series) SLR (Single-lens Reflex) Based on 35mm design Actual image seen in viewfinder Interchangeable lenses (more flexible composition) Ability to use filters More advanced metering and shutter system Little to no shutter delay Automatic, Program (Scene), Shutter Priority, Aperture Priority and Manual modes Flash hot shoe Pro models may not have pop-up flash or Program (scene) modes 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 viewfinder Much simpler design than SLRs. Light Path Lens Camera Body Viewfinder (front) Shutter Sensor or Film Viewfinder Focal Length LCD Screen (Digital) SLR Anatomy Through-the-lens (TTL) viewing (works like a periscope) Actual image (as exposed) is shown in the viewfinder Mirror 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 Path Lens Camera Body Focusing Screen Mirror (Pentaprism) Mirror (flips up) Shutter Sensor or Film Viewfinder Focal Length LCD Screen (Digital) Advantages Of Digital Instant gratification (big fun factor) see your images right away No 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 store Easier to make copies no need to send (or lose) originals Easier to manipulate no scanning required (you did that when you pressed the shutter) No need to spend hours in the darkroom Black-and-white just shades of grey colors No worries about film fading over time; digital images last for as long as your storage media doesnt die on you Less storage space no physical shelves to keep stacking Metadata information available for indexing and cataloging. Disadvantages Of Digital Image quality As good or better than 35mm in the right hands , but cannot compete with medium or large format film (yet) 1.5x cropping factor or focal length multiplier in SLRs due to smaller sensor Exposure much more critical 1/3 stop subtle in Velvia, but blatant in digital Blown highlights no information means no information; film is better at rendering overexposed areas more naturally Great shadow detail, but clipped highlights -- traded highlight detail for lower noise; most likely need to underexpose and correct in post Skilled user needed to extract the image quality equivalent to that of good film Very different workflow requires skill with computers and software, knowledge of color management and printing, web, email, etc. You are the photo lab youve traded darkroom chemicals for a digital darkroom Easy to lose images memory cards can become corrupted in-camera; photos are scattered all over your computer; hard drives die Slow camera is locked up once the buffer is filled until the images are completely written to the card Shutter delay (point-and-shoot) Digicams are much more expensive than film cameras and become obsolete sooner Slide shows projectors designed for business graphics render poor photographic quality and awful color. More megapixels = bigger files = more storage + faster computers Which Is Better? The apple or the orange? Each has their respective strengths and weaknesses. It all depends on what youre trying to accomplish. Everything in photography is a trade-off. Choosing A Digital Camera The number of megapixels isnt everything! More is not necessarily better, But more can be an advantage when cropping or printing big. Megapixel Madness How Many Pixels Do You Need? Assume 300 dpi (dots per inch) for a good quality print on a desktop printer Break down megapixels to length and width, then divide by 300 e.g. 6MP ~ 3008 x 2000 pixels (Nikon D70) 3008/300 = 10.027 in. 2000/300 = 6.667 in. BUT, different printers have different requirements Software can help upsize or downsize with varying results Large fudge factor, depending on chosen application and printer technology. Digital Camera Resolution Chart (Source: B&H Photo-Video-Pro Audio ) So, How Do I Choose A Camera? Ergonomics how does it feel in your hands? Size and weight of the camera Size and quality of the LCD Lens quality Sharpness Distortion Zoom capability (optical vs. digital) Digital zoom is evil! Metering capability Built-in flash Red-eye reduction Can you control it? Manual capability vs. automatic or program modes Battery life Media type Decide whats important to you based on how youll be using it! About The Cards Pick One Compact Flash SD MiniSD xD MultiMediaCard RS-MMC (Reduced-Size MultiMediaCard) SmartMedia Memory Stick Image source: Lexar I Bought A Camera Now What? Charge the battery Format the card Set up the camera Date and time Bells and whistles (literally!) Digital zoom if you can turn it off, do it! Mode: Auto, Program, Aperture Priority, Shutter Priority, Manual ISO White balance Color space (Never mind!) Image quality and file type JPEG (Joint Photo Experts Group) in-camera processing, lossy (small, medium, large), 8-bits (256 shades of color) per channel (16.7 million colors) TIFF (Tagged Image File Format) in-camera processing, uncompressed, lossless, 8-bits per channel RAW direct output from the sensor, little to no in-camera processing, 12-bit (4096 shades of color) per channel (68.7 billion colors) What are you waiting for?? Go shoot pictures! Recall Good photography depends on being able to execute two things well: Exposure Composition Composition The art of including the essence of what moves you about the scene in your photograph, while excluding any non-essential, distracting elements. Composition There are established guidelines, but ultimately, its about your artistic vision Very subjective Not always a conscious thing listen to your heart! Simplify, Simplify, Simplify! Simplify Simplify Simplify Simplify Simplify Simplify Composition You take the picture, but you make the photograph. Its about seeing the photograph in front of you. Its about design arranging all the elements of the scene in your viewfinder so they become something compelling to look at. Hold the viewers attention as their eyes travel around the frame. 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. Our eyes are naturally drawn to brighter, hotter elements. If those arent your subject(s), exclude them! Composition Do in in the viewfinder, not in Photoshop! Its always best to start with a good image. Photoshop doesnt make a bad photograph good, it makes a bad photograph big. Youre rendering a 3-D scene as a 2-D print. Frame it carefully! Try not to bullseye your subject in the frame. Dead center is deadly! Use the Rule Of Thirds the oldest trick in the book for composing a visually balanced and pleasing image. Rule Of Thirds Divide your scene into an imaginary tic-tac-toe grid, then place your subject(s) near any of the four intersections Use Those Lines! Diagonal lines are especially dynamic. Use them to lead the viewer to the subject, guide the viewer across the frame or create vanishing points. Find Grace The S-curve is a classic compositional device to create a sense of grace. Give moving subjects space to go. Dont place them so they are about to run off the frame. Tips For Better Composition Try not to cut off any body parts. Dont have trees or telephone poles growing out of your subjects heads. Tips For Better Composition Tell a story with your photographs Learn, Practice, Then Forget Remember, these are just guidelines, not hard and fast rules. Dont be afraid to experiment! Look for different viewpoints. Try tilting the camera. Try it blurry! You are only limited by your own creativity! Now That You Have Your Pictures Time for the workflow Why do you need a workflow? Because your photos are trapped in your card and somebody has to liberate them Because its too expensive not to get them out and print/email/put-them-on-the-web yourself Because you want artistic control over how your photos are displayed Now That You Have Your Pictures Typical Post-capture Workflow: Download And Store File naming Storage Metadata Edit Crop/Straighten Tone Contrast Color correction Sharpening Cataloging Output Printer Email Web Image source: Epson Download And Store Downloading directly from the camera can be slow usually USB 1.1 maximum transfer rate of 12Mbits/sec. Use a fast external card reader if possible USB 2.0 capable of up to 480Mbits/sec. Firewire (IEEE 1394) capable of up to 400Mbits/sec. Software available to download, rename, add metadata Downloader Pro (Breeze Systems) Photo Mechanic (Camera Bits) File naming is important. Use the same file naming scheme for your edits and originals. Metadata is essential. Help yourself find and figure out your photos later. Backups! Backups! Backups! Copy your newly downloaded images first thing before you do anything else! The Browser Allows you to look at all the photos on your computer Thumbnails and previews Sorting, ranking Batch renaming Manage metadata EXIF (Exchangeable Image File Format) IPTC (The International Press Telecommunications Council) Popular software packages have them built-in Adobe Photoshop Photo Mechanic iPhoto The Organizer Builds databases of information about your photos EXIF IPTC File names Folder names Allows searching of your photos regardless of where they are Popular software Adobe Photoshop Elements Extensis Portfolio iView MediaPro Canto Cumulus Time To Edit Crop and straighten Tone and contrast Color correction Creative sharpening Many software packages available: Adobe Corel Apple Microsoft Extensis Ulead JASC Nova Free/share-ware Etc. Why Adobe Photoshop? Because its the best! Because the camera is good, but you might be able to do better in post Because your in-camera technique is good, but you might be able to do better in post Because you might have been forced to do something like underexpose on purpose, and only you know how to deal with that Why Adobe Photoshop? Because you may want to create a piece of art out of your photos Adobe Photoshop Family Adobe Photoshop Album 2.0 casual snapshooters Adobe Photoshop Album Starter Edition 3.0 Adobe Photoshop Elements 3.0 photo enthusiasts and most amateur photographers (This is probably all you need!) Adobe Photoshop CS2 professional gold standard Sharing Your Photos Print Desktop printers Commercial printing services Shutterfly, Ofoto, etc. Costco Web Online services Shutterfly, Ofoto, etc. Web pages (72 dpi) Email Good for small files only! (72 dpi) Printing Tips Set the print size Set the correct printer and paper (including size, orientation, fit on paper) Your software gives you options, then your printer gives you options can be confusing Color management either let your software manage the colors, or let the printer do it, but not both! Set the color profile of the paper youre using Do a nozzle check beforehand. (Keep scrap plain paper around!) Clean the nozzles often. Use third-party inks and paper at your own peril! Email Tips If you dont have to, dont! Dont email big files! Anything ~1M or more is too big! Use software emailing features, or manually reduce the file size (72 dpi, 640 pixels is usually sufficient). Package up your images if you have many zip, etc. Better yet use the Web! Attach the images avoid placing them in the body of your email (in-line). Web Tips If you have already enhanced your photos, make sure your service (Shutterfly, Ofoto, etc.) doesnt enhance them again! If you manage your own web pages, use small files (72 dpi) Software available to create galleries Adobe Photoshop CompuPic ThumbsPlus Sharpening In digital terms, adding adjacent light and dark pixels to enhance contrast Amount how much (gas pedal) Halo (Radius) how many pixels affected Threshold how many surrounding pixels considered edge Different needs Print: inkjet, laser, offset, etc. Web/email (screen) After resizing Schools of thought For output only Workflow (artistic) sharpening Live Editing Session Parting Thoughts Good art comes of good craftspersonship. If It Moves You, Shoot It! Often! Practice! Practice! Practice! Anything and everything! Recommended Reading Photography Blue Pixel Personal Photo Coach: Digital Photography Tips from the Trenches by David Schloss Perfect Exposure: Jim Zuckerman's Secrets to Great Photographs by Jim Zuckerman Designing a Photograph: Visual Techniques for Making Your Photographs Work by Bill Smith Examples: The Making of 40 Photographs by Ansel Adams Successful Underwater Photography by Brian Skerry, Howard Hall Adobe Photoshop Adobe Photoshop CS2 for Photographers by Martin Evening The Photoshop CS2 Book for Digital Photographers by Scott Kelby The Photoshop Elements 3 Book for Digital Photographers by Scott Kelby Photoshop Restoration & Retouching by Katrin Eismann Photoshop Masking & Compositing by Katrin Eismann The Photoshop Show Starring Russell Brown by Russell Brown Adobe Photoshop CS2 Classroom in a Book by Adobe Creative Team Adobe Photoshop Elements 3.0 Classroom in a Book by Adobe Creative Team Photoshop on the Web Adobe Photoshop ( http://www.adobe.com/products/ photoshop /overview.html ) National Association of Photoshop Professionals (NAPP) ( http://www. photoshopuser .com/ ) Photoshop News ( http:// photoshopnews .com/ ) Photoshop Caf ( http://www. photoshopcafe .com/ ) Adobe Evangelists ( http://www. adobeevangelists .com/ ) Thank You For Coming! Now Go Take Pictures! Peter Liu Photography kaiscapes .com Supplemental Slides Begin Here Film Speed Trivia ASA A merican S tandards A ssociation. Most common film speed rating in the U.S. until the conversion to ISO. Only the name has changed. ISO I nternational S tandards O rganization. Most common film speed rating in the U.S. Doubling the value doubles the film speed. DIN D eutsche I ndustrie N orm . Based on a logarithmic scale where each increase represents 1/3 stop. E.g. ISO 800/30 on a roll of ISO (ASA) 800 film indicates that the DIN rating is 30.