Learning digital photography issue 2 page 1
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Learning digital photography issue 2

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Basic digital photography for beginners.

Text of Learning digital photography issue 2

  • In photography, the sunny 16 rule is a method used to estimate correct daylight expo-

    sures without using a light

    meter. The rule is based on the

    quantity of light falling on the

    scene and or subject and was

    given as an easy formula printed

    on datasheets included in every

    box of film sold.

    Basically, the sunny 16 rule

    says on a sunny day, set the aperture to f/16 and set the

    shutter speed to the reciprocal

    ISO number. For example, if

    you set the ISO to100, set the

    shutter speed to 1/100 second

    or to the nearest shutter speed

    to approximate the reciprocal

    of the ISO setting. With the f-

    number constant, the shutter

    speed varies according to the

    ISO.

    If youre shooting in manual mode, keep your camera set so

    that youre ready for any photo opportunity. As a quick guide to

    setting aperture in various

    conditions, set the f-number as

    shown in the following table:

    The Sunny 16 Rule

    Taking Sharp Photographs

    There are many reason

    why your photographs might not look as sharp

    as youd like. The main causes:

    Poor Focus. Focusing on the wrong part of the

    image, being too close to your subject for the cam-

    era to focus, or selecting an aperture that gener-

    ates a very narrow depth

    of field all contribute to poor focus.

    Subject Movement creates blur in shots is if

    your shutter speed is too slow.

    Camera Shake can cause blur if you move

    even slightly while taking the image. Use a higher

    shutter speed or a tripod

    to keep the camera still. Noise caused by high

    ISO settings make a pho-to look pixilated, covered

    with little dots all over. Watch your ISO settings

    if you want crisp, clean photos.

    August 2008 Volume 1, Issue 2

    askvalda@gmail.com

    digitalphotography

    Inside...

    Understanding

    Histograms

    How to Read

    Histograms

    Learning Digital Photography

    Presented by

    Valda Hilley at the

    Fitton Center for

    Creative Arts

    101 S. Monument

    Ave., Hamilton, OH

    45011

    The Back

    Page...

    Shooting RAW

    Evaluating Your

    Images

    Photo Assignment

    General Information

    Aperture Lighting

    Conditions

    Shadow Detail

    f/22 Snow or

    bright sand

    Distinct with glare

    f/16 Bright sun Distinct

    f/11 Hazy or

    Slight overcast

    Soft around edges

    f/8 Overcast Barely visible

    f/5.6 Heavy over-

    cast or shade

    No shadows

    On a bright

    day, the

    correct

    exposure for

    any subject is

    f/16 at the

    shutter speed

    nearest to the

    reciprocal of

    the ISO setting.

  • Understanding Histograms

    Page 2 askvalda@gmail.com

    A histogram is a graph (bar chart) that can help you evaluate a digital image. It shows the relative distribution of pixel color values

    from black to white using a linear scale of 256 levels where 0 is solid black and 255 is pure white. The darkest shadow values are shown

    at the left end of the horizontal axis, and the lightest values or high-lights are at the right end.

    The peaks and valleys at each position across the graph represent the number of pixels at each level. A tall vertical line indicates a

    large number of pixels, and a short line indicates a relatively small

    number of pixels at a particular level. Together, all the vertical lines make up the shape of the histogram.

    Use the histogram to judge the brightness of a shot image noting

    that the greater the bias towards the left of the axis, the darker the image, and bias towards the right of the axis, the brighter the image.

    If the image is too dark, adjust the camera's exposure compensation to a positive value and if too bright, adjust to a negative value.

    How to Read Histograms

    Values across the range with

    gentle peaks, good exposure.

    Mostly low values (weighted to

    the left) for low key/dark images.

    Mostly high values (weighted to

    the right) for high key/bright

    images.

    A sharp peak toward one

    extreme or the other, with few

    values across the axis indicate

    over or under exposure.

    A comb-like histogram indicates

    a poor image with missing values

    and too many of the same values.

    Working with the Levels

    Histogram Image editing programs have a tool called

    Levels used to precisely determine and

    adjust the brightness, color, and contrast of

    an image. Like a cameras histogram, the Levels histogram shows the brightness of

    the image, shadows on the left side and

    highlights on the right, the distribution of

    pixel values. The three triangles directly

    beneath the histogram represent shadows

    (black), highlights (white), and midtones

    (gray). If an image has colors across the

    entire brightness range, the graph extends

    from black triangle to white triangle as

    shown in the histograms for the pictures to

    the left. The tones in these images are well

    distributed from black (0) to white (255).

    To adjust the black, white , and gray points

    of an image 1) Drag the left triangle to the

    right to the point where the histogram

    indicates that the darkest colors begin. 2)

    Drag the right triangle to the left to the

    point where the histogram indicates that

    the lightest colors begin. 3) Drag the mid-

    dle triangle a short distance toward the left

    side to lighten the midtones.

  • Page 3 Volume 1, Issue 2

    6:44 p.m.

    Focal length

    18mm

    Shutter speed

    1/320s Aperture

    F/9

    6:45 p.m.

    Focal Length

    50mm

    Shutter Speed

    1/400s

    Aperture

    F/10

    Exposure

    Compensation

    1.0 EV

    6:46 p.m.

    Focal Length

    18mm

    Shutter speed

    1/320s

    Aperture

    F/9

    June 30, 2008 Liberty Playland in West Chester. Nikon D80 fitted with an 18-135 F/3.56-F/5.6 zoom lens.

    Camera settings (except where noted): ISO 100, Programmed Auto, Center-weighted metering mode. The images were cropped to fit space.

    Shape is relative so theres no such thing as a correct shape for a histogram. Every image is different. Take a look at these three histograms.

    Each is correct for the corresponding image yet different from image to image.

    Many digital cameras include a histogram to

    assist you in making proper exposures. Use the camera's histogram to evaluate the range of

    tones in a capture, and if possible, reshoot the image with different exposure settings to get a

    better image.

    These landscapes have data distributed across

    the entire axis of the histogram. This indicates a wide range of tones. If you have a histogram that

    indicates a low dynamic range, or a lack of con-trast, you can use tools in an image editing pro-

    gram like Photoshop to expand the range of values in the image.

  • A RAW file is essentially the data

    that the camera's chip recorded

    along with information about the

    cameras settings. A JPG file is one that has had the camera apply white

    balance, contrast, saturation, and file

    compression.

    Reasons to Shoot JPG

    A JPG file directly from the cam-

    era can often produce high quality

    prints.

    For many applications image

    quality is sufficient (snapshots,

    web images).

    Files are smaller, more of them fit

    on a storage card, and theyre

    easily transmitted online.

    Many people don't have the time

    or desire to post process their

    files.

    Many cameras cant shoot quickly when working in raw. Some cam-

    eras can't record raw files.

    Reasons to Shoot Raw

    A RAW file holds exactly what

    the imaging chip recorded. Noth-

    ing more.

    To extract the maximum possible

    image quality, whether now or in

    the future.

    The camera does not set white

    balance when recording RAW

    files. It tags them with the

    camera's white balance setting

    at the time you take the pic-

    ture, but the actual image data

    remains unchanged. This allows

    you to set any color tempera-

    ture and white balance you

    want after the fact without

    degrading the image file. Note

    that once the file has had in

    camera processing applied such

    as in JPG files, you can no long-

    er properly set white balance.

    The raw file is tagged with

    contrast and saturation infor-

    mation as set in the camera, but

    the actual image data has not been

    changed. You can set contrast and

    saturation on a per-image basis

    rather than use one or two gener-

    alized settings for all images.

    Shooting Raw

    About Valda Hilley

    Ive had many occupations over the years; engineer, author, IT Consultant; photographer is

    one that gives me great joy. Im eager to share it with you. -

    askvalda@gmail.com

    Learn Digital Photography

    Tuesdays 6:00 to 8:30 p.m.

    Learn Adobe Photoshop

    Thursdays 6:00 to 8:30 p.m.

    At the Fitton Center for the Creative Arts

    In Hamilton, Ohio

    Assignment:

    Get out and Shoot

    Flora 1. Choose a focal length that will

    give you the picture you want. (Zoom in or out) A macro

    lens or