Learning digital photography issue 2
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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 you’re shooting in manual
mode, keep your camera set so
that you’re 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 you’d 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
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 [email protected]
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 camera’s 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 there’s 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
camera’s 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 they’re
easily transmitted online.
Many people don't have the time
or desire to post process their
files.
Many cameras can’t 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
I’ve had many occupations
over the years; engineer, author, IT Consultant; photographer is
one that gives me great joy. I’m eager to share it with you. -
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 macro setting will al-low you to take a picture of
the smallest part of a flower. You can capture a landscape
of flowers with a wide-angle lens and zoom to a telephoto
length to capture the fleeting butterfly or bee fluttering
flower to flower.
2. Use a low ISO to get bright colors. An ISO of 50 or 100
will give you bright colors. Use a tripod to prevent any mo-
tion when shooting at low ISO.
3. Use a tripod to allow you to
slow your shutter speed down to capture light and color.
4. Choose your subject such as the stamen of a single flower,
a single flower or a field of flowers. When shooting a field
of flowers, choose a point of interest so that your eye will
be drawn to it in the final pic-ture.
5. Walk around your subject and
look for the best lighting and angle. Use backlighting to high-
light the transparency of the petals.
6. Decide on the background. If
you want a muted background, shoot with a wide aperture (a
low f-stop number).
7. Use your flash to fill any
shadows that maybe lurking around your subject.
8. Shoot the flower from differ-ent angles such as above,
below or from the side to capture interesting views of the same flower.
9. Stop, breathe. Use a tripod.
10. Enjoy! Use a tripod.
Copyright © 2008
All Rights Reserved.
No guarantee or warranty, expressed or implied, is made about
the value or stability of the infor-
mation or links made herein.
Trademarks are the
property of their
respective trademark holders.
Evaluating Your Images What do you look for when decid-
ing if the image you are looking at
can be improved?
Tonal Range Tonal range or contrast, is the
range of brightness in an image from
pure black to pure white. Images
that use the full tonal range look rich
and crisp, their colors are vibrant
with smooth transitions between
tones. Those that don't use the full
range lack contrast, usually look flat
and dull and details might be missing
in highlight and shadow areas or the
image could be too dark or light.
Colors Your eyes perceive color in terms
of hue, saturation, and lightness. Hue
is the actual color (red, green, blue,
etc.), while the saturation and light-
ness are characteristics of the hue
that can be adjusted to alter the hue
in some way.
Saturation is the strength or purity
of the color. If you adjust saturation
through its entire range, colors go
from rich and vibrant to dark gray.
Lightness, is the relative light-
ness or darkness of the color.
Lightness is reduced by adding
black to the color mix and in-
creased by adding white. If you
adjust brightness through its
entire range, colors go from
white to black.
As you decrease saturation,
colors become muddier and
finally gray. As you decrease
lightness, colors become darker
and eventually black.
A color cast usually occurs
when one or more of the tred,
green, or blue color components are
too high or low over the entire
image. This can be caused by im-
proper white balance, by photo-
graphing a scene lit by more than
one type of light source, or even a
subject picking up colors reflected
from other surfaces. You can identify
a color cast by looking at areas in an
image that should be neutral, white,
or gray. If these areas have any col-
ors mixed in, the image has a color
cast that you should remove.
Sharpness The apparent sharpness of an
image depends on how much con-
trast there is along edges and lines. If
an image looks soft, it can often be
improved by a sharpening process
that adds contrast along lines and
edges.
Noise If you used a long shutter speed or
high ISO setting to take a photo, it
might contain noise. Look for ran-
domly colored pixels in dark areas
that look like grain.