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DESCRIPTIONPresentation on digital photography I gave in 2005 at the Saratoga Library.
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Peter Liu Photography
Digital Photography I
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From two Greek words meaning “drawing with light”: φως phos ("light") γραφις 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.”
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“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.”
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Hard Light – high contrast, well-defined shadows
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Soft Light – diffused, rich colors
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Overhead Light – harsh shadows
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Front Light – flat, lacks dimension
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Side Light – evokes mood, accentuates shapes
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Back Light – may need to fill, makes silhouettes
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Overcast Light – low contrast, muted shadows, good for detail
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Characteristics Of LightQuality
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
SourceAmbient – daylight, tungsten, flourescent, firelightArtificial – flash, tungsten
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)
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Characteristics Of LightColor 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.
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Why Are You Telling Us All This??
Because good photography depends on being able to execute two things well:
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ExposureA combination of three factors sometimes known as the “Photographic Triangle”:Shutter SpeedApertureISO
how quickly light is being captured through how big an opening onto how sensitive a surface
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ShutterA camera’s 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
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Shutter Speed – Fast
1/1600 sec., stops action
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Shutter Speed – SlowSilky, cool, edgy effects
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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
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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
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Aperture The size of the opening is expressed as an f-stop
number: 1.4 2.0 2.8 4 5.6 8 11 16 22 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.
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Aperture And Depth Of Fieldf/5.6
Shallow depth of field
f/22Deep depth of field
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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.
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Aperture And Shutter SpeedThe following reciprocals will yield the same exposure:
What changes is how much is sharp and in focus.
f/2.8 1/500 sec.f/4 1/250 sec.f/5.6 1/125 sec.f/8 1/60 sec.f/11 1/30 sec.f/16 1/15 sec.f/22 1/8 sec.
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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!
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Tricky Metering Situations
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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
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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 (Ain’t 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!
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Higher ISO = More Noise!
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So…Exposure depends on:
Shutter Speed – how fastAperture – how muchISO – how sensitive
And color is a function of:White Balance – how hot
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Which camera you choose is a function of how much you want control those factors!
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CamerasTwo popular types of cameras on the
market for the consumer
Point-and-shootSLR (Single-lens Reflex)
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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
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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.
Sensor or Film
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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.
Mirror (flips up)
Sensor or Film
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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, it’s 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 doesn’t die on you Less storage space – no physical shelves to keep stacking Metadata information available for indexing and cataloging.
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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 – you’ve 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
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Which Is Better?The apple or the orange?
Each has their respective strengths and weaknesses.
It all depends on what you’re trying to accomplish.
Everything in photography is a trade-off.
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Choosing A Digital Camera
The number of megapixels isn’t everything!
More is not necessarily better,But more can be an advantage when cropping or
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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 300e.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.
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Digital Camera Resolution Chart(Source: B&H Photo-Video-Pro Audio)
Print Size* * * Capture Resolution Video Display* 2x3" 4x5"/ 4x6" 5x7" 8x10" 11x14" 16x20"
320x240 Acceptable Good Acceptable Poor Poor Poor Poor 640x480 - 0.3 Megapixel Good Excellent Good Poor Poor Poor Poor
800x600 Excellent Photo Quality Very Good Acceptable Poor Poor Poor
1024x768 Excellent Photo Quality Excellent Good Acceptable Poor Poor
1280x960 - 1 Megapixel Excellent Photo
Quality Very Good Good Poor Poor
1536x1180 Excellent** Photo Quality
Photo Quality Excellent Very Good Acceptable poor
1600x1200 - 2 Megapixel Excellent** Photo
Quality Very Good Acceptable Acceptable
2048x1536 - 3 Megapixel Excellent** Photo
Quality Excellent Good Acceptable
2240x1680 - 4 Megapixel Excellent** Photo
Quality Very Good Good
2560x1920 - 5 Megapixel Excellent** Photo
Quality Excellent Very Good
3032x2008 - 6 Megapixel Excellent** Photo
Poor Noticeably Grainy (pixelated) Acceptable Obviously not a real photo, but some details are visible Good Can tell it is not a photo but most details are discernable Very Good Can tell it is not a photo at normal distance, but good enough for many uses Excellent Difficult to tell from real photo at normal viewing distance Photo Quality On a photo-quality printer, the human eye should not be able to tell the difference at a normal
viewing distance * Either television or computer display (e.g. Web Page) ** Will produce an excessively large file size that would be inappropriate for web applications *** Using a typical Photo Quality Desktop printer
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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 what’s important to you based on how you’ll be using it!
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About The CardsPick One
Compact Flash SD MiniSD xD
MultiMediaCard RS-MMC (Reduced-Size
SmartMedia Memory Stick
Image source: Lexar
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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!
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Good photography depends on being able to execute two things well:
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“The art of including the essence of what moves you about the
scene in your photograph, while excluding any non-essential,
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Composition There are established “guidelines”,
but ultimately, it’s about your artistic vision
Very subjective Not always a conscious thing –
listen to your heart! Simplify, Simplify, Simplify!
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Composition “You take the picture, but you make the photograph.” It’s about seeing the photograph in front of you. It’s 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, somebody’s toe, etc.
Our eyes are naturally drawn to brighter, “hotter” elements. If those aren’t your subject(s), exclude them!
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Composition Do in in the viewfinder, not in Photoshop! It’s always
best to start with a good image. “Photoshop doesn’t make a bad photograph good, it makes a
bad photograph big.” You’re 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.
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Rule Of Thirds
Divide your scene into an imaginary “tic-tac-toe” grid, then place your subject(s) near any of the four intersections
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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”.
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Find GraceThe S-curve is a classic compositional device to create a sense of grace.
Give moving subjects space to go. Don’t place them so they are about to run off the frame.
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Tips For Better CompositionTry not to cut off any
Don’t have trees or telephone poles
growing out of your subjects’ heads.
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Tips For Better Composition
Tell a story with your photographs
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Learn, Practice, Then ForgetRemember, these are just guidelines, not hard and fast rules.
Don’t be afraid to experiment! Look for different viewpoints.Try tilting the camera. Try it
You are only limited by your own creativity!
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Now That You Have Your PicturesTime for the workflow
Why do you need a workflow?Because your photos are trapped in your card
and somebody has to liberate them
Because it’s 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
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Now That You Have Your PicturesTypical Post-capture Workflow:Download And
StoreFile namingStorageMetadata Edit
Image source: Epson
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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. Helpyourself find and figure out your photos later.
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Backups! Backups! Backups!Copy your newly
downloaded images first thing before you
do anything else!
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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
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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
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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.
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Why Adobe Photoshop?Because it’s 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
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Why Adobe Photoshop?
Because you may want to create a
piece of art out of your photos…
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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
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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)
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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 you’re 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!
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Email Tips If you don’t have to, don’t! Don’t 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).
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Web Tips If you have already enhanced your photos,
make sure your service (Shutterfly, Ofoto, etc.) doesn’t enhance them again!
If you manage your own web pages, use small files (72 dpi)
Software available to create galleries Adobe Photoshop CompuPic ThumbsPlus
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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
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Live Editing Session…
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“Good art comes of good craftspersonship.”
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If It Moves You, Shoot It! Often!Anything and
Practice! Practice! Practice!
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Recommended ReadingPhotographyBlue Pixel Personal Photo Coach: Digital Photography Tips from the Trenches by David SchlossPerfect Exposure: Jim Zuckerman's Secrets to Great Photographs by Jim ZuckermanDesigning a Photograph: Visual Techniques for Making Your Photographs Work by Bill Smith Examples: The Making of 40 Photographs by Ansel AdamsSuccessful Underwater Photography by Brian Skerry, Howard Hall
Adobe PhotoshopAdobe Photoshop CS2 for Photographers by Martin EveningThe Photoshop CS2 Book for Digital Photographers by Scott KelbyThe Photoshop Elements 3 Book for Digital Photographers by Scott KelbyPhotoshop Restoration & Retouching by Katrin EismannPhotoshop Masking & Compositing by Katrin EismannThe Photoshop Show Starring Russell Brown by Russell BrownAdobe Photoshop CS2 Classroom in a Book by Adobe Creative TeamAdobe Photoshop Elements 3.0 Classroom in a Book by Adobe Creative Team
Photoshop on the WebAdobe 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 Café (http://www.photoshopcafe.com/)Adobe Evangelists (http://www.adobeevangelists.com/)
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Thank You For Coming!
Now Go Take Pictures!
Peter Liu Photography
Supplemental Slides Begin Here
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Film Speed Trivia ASA – American Standards Association. Most
common film speed rating in the U.S. until the conversion to ISO. Only the name has changed.
ISO – International Standards Organization. Most common film speed rating in the U.S. Doubling the value doubles the film speed.
DIN – Deutsche Industrie Norm. 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.