Transcript
Page 1: 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 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

[email protected]

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.

Page 2: Learning digital photography issue 2

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: Learning digital photography issue 2

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.

Page 4: Learning digital photography issue 2

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. -

[email protected]

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.