United States
Environmental Protection
Agency
Region 10
1200 Sixth Avenue
Seattle WA
July 1986
vvEPA Fundamentals of
Photography for
Government
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Fundamentals of Photography for Government
When you take a Government camera with Government film out on an assignment,
you are making the effort to visually document key activities related to your work.
Success in this task requires a commitment on your part to gain knowledge of and
insight into photography. This publication is intended to help you in this effort.
The first step in the learning process is to understand the 3-cornered, 3-way
relationship between light, film, and camera. Competence begins with a grasp of the
interplay between these elements.
Normally we take light for granted — our eyes adjust to light automatically. But when
you use light as a tool for making photo-images, you must become sensitive to certain
qualities of both the light and the subject illuminated.
CONSIDER:
• The relative brightness of light and subject.
• The kind of source. Sun? Electrical light?
• The direction of the light
• The relative brightness of the surrounds.
These elements are crucial to certain decisions you, as a photographer, will have to
make. And successful picture taking is based on a foundation of correct decision
making. The relative brightness and the kind of source directly influence your choice
of film. And the direction of light and subject surrounds influence how you set your
camera's controls. It is tremendously helpful if you have a prior knowledge of the
conditions under which you will photograph. This knowledge is the basis of the
selection of camera and lens, the basis of the selection of film, and the basis of the
decision-making process that you, as a Government photographer, will be involved in.
Film
Film is your medium, your image-recording tool. All films use a very limited range of
light to make an image. The limits imposed are determined by the rate at which light-
sensitive silver halide crystals coated on the film respond to light.
Larger silver crystals are more light-sensitive and respond to light more quickly than
smaller ones. Film coated with such crystals are said to be fast and are given a
numerically higher rating. Slow films are coated with smaller crystals and respond to
light less readily.
All film, no matter what its rated speed, responds to a much narrower range of light
than the human eye. That very limited range of light brightness where a film will
produce a useable image is what the photographer has to work with. Pictures made
under conditions which exceed this limited range of light brightness striking the film will
be difficult or impossible to use as records or evidence.
Overexposed
(A very bright, very light final picture)
Underexposed
(A very dark, very dim final picture)
Optimum Exposure
(Final picture exactly as the photographer desired)
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Worthless Exposed Film
(In excess of either the limits of acceptable overexposure or
underexposure - pictures in which the subject cannot be made visible)
The range of acceptable exposure on both sides of the optimum exposure is
called the film's latitude.
Films are classified by the rate at which light forms images on the film by the
ASA/ISO film speed number system. The slower the film's response to light, the lower
the number; the faster the film responds to light, the higher the number. For example,
ASA/ISO 25 is about the slowest film commonly available, and ASA/ISO 1000 is the
fastest.
Film Speeds:
Advantages and Limitations
ASA/ISO
25-64
ASA/ISO
64-200
ASA/ISO
400-1000
Good for fine detail,
generous latitude,
low contrast.
Adequate detail and
latitude, medium
contrast, better for
action or low light
levels than slow
films.
Good for action and
low light levels, dark
subjects and
surrounds.
Limited to daylight
hours. Less light,
bad weather, may
require flash or
tripod.
Slight loss of fine
detail, limited
extension of daylight
photo activity, flash
or a tripod may still
be needed in low
light.
Loss of fine detail,
narrow latitude, high
contrast.
These generalized statements apply to both color and black and white films. See
specific film commentary in the Photograph for Evidence section.
Camera
There is light and a subject which reflects light in varying degrees -
light to dark. There is film, responding to a limited range of light intensity to form the
image. And to weld the two, to match and balance, to catch the picture is the camera
(and, of course, the operator).
This machine performs several important functions - some obvious and some not:
• It holds the film flat, centered to the lens, and at 90° to the lens axis.
• It provides a means for you to view and frame your photo before you take it.
• It moves fresh, unexposed film into the flat, centered, 90° position behind the
lens for the next picture.
It gives you the ability to take the picture exactly when you want to.
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But most important of all -
The camera provides the controlling functions for adjusting the amount
of light that will strike the film to make the image.
These controlling functions are shutter speed and f-stop. They govern Time and
Volume.
Time is controlled by the shutter, which is normally closed, admitting no light at all.
When the shutter operates, a blink of light flashes on the film. You regulate the duration
of this blink by controlling the shutter's mechanism. This blink is measured in fractions
of a second, usually beginning with one second. The standard progression of the
shutter's blinks for today's cameras is 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250,
1/500, and 1/1000 of a second.
The relationship between these fractions of a second is an important concept. Moving
the shutter speed control towards smaller (shorter) slices of time, each new shutter
speed selected is 1/2 the value of the previous setting. Moving the shutter speed control
towards larger (longer) amounts of time, each new shutter speed is twice (2X) the
value of the previous setting. Remember this halving and doubling relationship!
The volume of light admitted to the film during shutter operation — when you take
the picture — is a function of the lens opening, called aperture. Apertures are
standardized by 'f numbers (referred to as 'f stops).
When selecting the f-stops, it is crucial to understand that each subsequent
(numerically higher) 'f number will result in a reduction of the volume of light striking
the film equal to half {1/2) the volume at the previous setting. Conversely, starting at
the smallest aperture (usually f22), each numerically lower T number selected will
result in a doubling (2X) of the volume of light striking the film when the picture is
taken. Remember this halving and doubling relationship!
Each single increment of change in either the lens aperture control or the shutter
speed is called a stop. You either increase or decrease exposure by one or more stops.
When you wish to refer specifically to an increment of change in lens aperture, use the
term 'f-stop'.
The halving-doubling relationship of the shutter speeds results in the same changes in
exposure as the doubling-halving relationship of the lens aperture control. This
'equivalency' means that for any one given correct exposure, an array of shutter speed
and aperture combinations will deliver that exposure!
1st Example: ASA/ISO 25 Film
in Bright Daylight
f8 at 1/125 sec.
Decreasing Volume/Increasing Time Increasing Volume/Decreasing Time
f11 at 1/60 sec. f5.6 at 1/250sec.
f16 at 1/30 sec. f4.0 at 1/500 sec.
f22 at 1/15 sec. f2.8 at 1/1000 sec.
(All these give the same exposure!)
2nd Example: ASA/ISO 400 Film
in Bright Daylight
f16 at 1/500 sec.
Decreasing Volume/Increasing Time Increasing Volume/Decreasing Time
f22 at 1/250 sec. f11 at 1/1000sec.
(All these give the same exposure!)
Notice how limited fast film is when used in unsuitable conditions.
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3rd Example: ASA/ISO 400 Film
Nighttime Indoors — By Room light
f2.8 at 1/60 sec.
Decreasing Volume/Increasing Time Increasing Volume/Decreasing Time
fl.4 at 1/250 sec. f22 at 1 sec.
f2.0 at 1/125 sec. f16 at Vi sec.
f4 at 1/30 sec. f11 at V* sec.
f5.6 at 1/15sec. f8 at 1/8 sec.
(All these give the same exposure!)
The equivalency relationship of lens apertures and shutter speeds ties into the
ASA/ISO film speed scale as follows: Each doubling of the ASA/ISO film speed will
result in a one stop reduction of exposure for any given subject-lighting situation. (= Vz
the previous exposure). Any reduction by half of the ASA/ISO number will result in a
one stop increase of exposure for any given subject-lighting situation.
Examples:
ASA/ISO 25 Bright f8 at 1/125 changes by
ASA/ISO 64 Daylight f8 at 1/250 1 stop
ASA/ISO 25 Bright f8 at 1/125 changes by
ASA/ISO 200 Daylight f8 at 1/1000 3 stops
ASA/ISO 25 Sunset f5.6 at 1/8 changes by
ASA/ISO 400 f5.6 at 1/125 4 stops
All of this exposure change through different film speed must be considered
when selecting film.
To sum up, as you reduce the volume of light transmitted by the lens to the film, you
must increase the length of time this light strikes the film in order to keep an equivalent
total exposure. Likewise, as you decrease the time of exposure, you must increase the
volume of light by an equivalent amount to maintain the same exposure.
What this span of alternate exposure settings means is that the light-camera-film
interplay may be adjusted to suit the desires of the photographer and the needs of the
situation. For example, if you are photographing action, and wish to stop or "freeze"
the motion, reset the exposure towards smaller (shorter) amounts of time (shutter
speed) and larger volumes of light (f-stop). By maintaining this equivalency, the
exposure will remain the same. If you are shooting landscapes, and want the great depth
of field that comes with small lens openings, and there is little or no motion of subject,
use a tripod or some other steady rest and stop the lens down as far as you wish. With
the reduction in the volume of light, the time must increase. When equivalency to the
base exposure is reached, take the picture.
The simple single focal length lens of 50-55 mm size is standard with most new
camera purchases. After that, the choice of lenses facing the photographer is
staggering. Almost all of these lenses share some common features, such as:
• Focusing mechanism.
• Adjustable aperture and control ring.
• Lens to camera mount.
• Depth of field and distance scales.
• Mechanism for coupling to camera body for various automatic
functions.
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Of these features, depth of field will pose the most problems for the beginning
photographer. Some general statements about depth of field that will help are:
• Depth of field is the zone of acceptable sharpness of image in the lens
field of view.
• Depth of field varies as a function of two other variables:
1. Focus distance.
2. Lens aperture selected.
• Depth of field increases as focus distance increases.
• Depth of field increases as the diameter of the aperture decreases.
• Depth of field relationship to focus distance and aperture selected is
shown for any lens by the depth of field scale on the lens barrel.
At Last! The Photographer
When you decide to take some pictures, think about when you are going to take
them - consider the time of day and the weather. Perhaps more important, look at and
think about what is going to be your subject and surrounds. With all this in mind, select
your film.
If your camera is an EPA or a recent generation automated camera, you will benefit
from a recent innovation in camera design — automatic exposure control.
All of the foregoing information about apertures and shutter speeds and film has led
you to this point. Now you are going to discover that, thanks to your modern camera,
none of this information is going to have much direct bearing or relevancy on your
actions prior to pushing the shutter button. The camera does it all!
Well. . .almost. You still have some actions to take, some decisions to make, choices
to consider — Let's go through them.
• You've picked the film you're going to use. Now, check that your
camera is equipped with functioning batteries. Always carry a spare
set.
• Check and double check that the correct film speed (ASA/ISO) number
is indicated on the camera's film speed dial. A mistake here could
waste the entire roll of film.
• Consider lens focal length and decide if you should use a different lens
than the standard item already on the camera.
• And finally, with most of today's cameras, you have to choose what
mode of camera automation the picture will be taken in! This is a
subject you can learn more about in your camera's instruction book or
manual. But keep in mind that some form of manual control is almost
always provided for in modern, automated cameras.
But despite all the automation available to the photographer today, a full
understanding of the fundamentals outlined in these pages will help you to take better
pictures.
For specifics on film selection and photographic techniques, read the following
chapter Photography for Evidence.
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Photography for Evidence
Now is a time at EPA when the enforcement of environmental laws depends to an
ever greater degree on the activities of the data gatherers. And increasingly,
photography plays an important role in that process. The investment of time and
material in photography for data and evidence can only be justified by the quality and
usefulness of the results. What follows is a collection of facts and insights aimed at
helping you optimize the results of your photographic efforts.
Equipment and Techniques
• Where precision in aiming and focusing the camera is essential...
• Where exposure determinations are difficult...
• Where picture taking at a distance or up very close may be part of the
same assignment.. .
• Where action sequence pictures may be vital to documentation...
Then selection of a single lens reflex camera with appropriate accessory equipment
becomes necessary. This type of camera, with it's ability to measure exposure through
the picture-taking lens, and it's adaptability to a wide range of lenses, motor drives, and
special purpose accessories, is the most useful instrument the Government
photographer can employ.
However, there are tradeoffs. Single lens cameras and accessories are bulky, heavy,
noisy, and not very suitable for subtle picture taking.
• Where speed of operation is important.. .
• Where silent operation is desirable. ..
• When the camera must be concealed.. .
Then select one of the small fixed-lens, simple-focusing cameras. Compact, light-
weight, with automatic exposure and a wide angle lens as standard, these instruments
are excellent for 'grab' shots. . .picture taking on the move. The tradeoffs are a lack of
flexibility and an absence of precision in aiming and focusing. INot really necessary in
this type of camera).
Most of today's 35mm cameras have provision for automatic exposure adjustment.
But, the photographer must:
• Check for working batteries in the camera, and the availability of fresh
spare batteries.
• Ensure that the camera's ASA/ISO film speed setting is correct for the
film being used.
Camera automated exposure systems work well, but there are exceptions:
• Where the light source is strong and direct — (bright sun, single light
bulb, one window), beware of high contrast'. Where the subject/scene
incorporates both very bright and very dark areas, beware of high
contrast)
Where high contrast exists, with brights and darks in the picture, and little in the way
of medium tone values, the photographer must:
• Make a judgment call as to which part of the viewed image is most
important.
• Override the camera's exposure automation correctly for the desired
result.
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Since most camera metering systems read light intensities and average them, high
contrast picture situations will fool the exposure automation. You have to identify the
problem, make the judgment call, and adjust your camera to compensate for the
problem.
Example
Judgment Call #1
Detail in the brightest area is the most important. Adjust camera override
towards underexposure (1/2X, 1/4X, or -1 or -2).
Judgment Call 92
Detail in the darkest area is most important. Adjust camera override towards
overexposure (2X, 4X, or +1 or +2).
Return override to neutral when need for compensation is over!
Since an accurate exposure determination may be difficult, and since film is
comparatively cheap — bracket your exposures! Take two, three, or even four
pictures of the same shot at different settings, using your judgment call as a guide.
Exposure compensation may also be accomplished by doubling the ASA/ISO
number for each stop of underexposure desired. Resetting to half the previous
ASA/ISO number will provide one stop of overexposure. Remember to reset to the
proper ASA/ISO number for your film when the need for exposure compensation is
past.
You may expect to encounter high contrast situations on any bright, cloudless, sunny
day, and at any time dark objects are positioned against a light background, or the
reverse. Beware of including too much sky in your pictures, and be aware of
reflected light when photographing over or around water. Strong directional sidelight
will produce harsh shadows, and any interior pictures that include light bulbs (lit) or
windows will cause problems. Just remember: Make your judgment call, alter the
exposure compensation correctly, and then, to make sure, bracket the
exposure.
Using a single lens reflex camera means you are going to confront the complexities of
lens interchangeability and the many choices of lenses which fit and work on your
camera.
Because its perspective most closely matches that of the human eye, the lenses in the
50-55 millimeter focal length are termed normal focal length. Lenses with focal lengths
of lower numerical value are called wide angle, while lenses with higher numbered focal
lengths are called telephoto.
Zoom lenses offer a continuous range of focal lengths in one lens. Some zoom lenses
run from wide angle to normal, some from normal focal length to telephoto, and some
zoom lenses offer a full range from wide angle to telephoto.
For evidential photography, lenses are used in the following ways. Normal and wide-
angle lenses are suitable for site and area overviews. But remember that the wide
angle lens distorts perspective and distance. Also, because a wide angle lens takes
in a wider field of view, the apparent size of everything in the picture will be reduced.
Use a macro lens for label and close-up photography. A less satisfactory solution is
the zoom lens with macro capability. Because of depth of field limitations, use a tripod
and stop the lens down for best results (f22 or f32 preferred). When you cannot use a
tripod, use the smallest aperture consistent with a shutter speed of not less than 1/60
second, and avoid focusing too closely.
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Telephoto lenses offer magnification of image size with a somewhat unrea''stic
perspective.
135mm = 2+ powers of magnification for a 35mm camera.
200mm = 4 powers of magnification for a 35mm camera.
400mm = 8 powers of magnification for a 35mm camera.
500mm = 10 powers of magnification for a 35mm camera.
Every increase in magnification increases the potential for loss of sharpness due to
camera motion. A good rule of thumb for handholding a camera-telephoto lens
combination is to never use a shutter speed less than the focal length of the lens.
Use a tripod wherever and whenever possible. The selection of faster films for
photography with telephoto lenses is also beneficial.
When photographing in the field with a tripod, try to avoid setting up near roads and
highways that are used by heavy traffic. Ground vibration can destroy image sharpness.
Filtration for evidentiary photography with color film may be beneficial. Here is a list
of the most useful filters and their applications.
UV-1 Cuts excess blue color cast above 4000ft. altitude.
Skylight Cuts excess blue color cast, has a very slight warming effect.
81A Warming filter;good for open shade photography, and for
use on days of heavy overcast.
80A & 808 Color conversion filters for daylight films used under
tungsten light, 2-3 stop filter factor.
85A Color conversion filter for tungsten films used with daylight,
1 1/2-2 stop filter factor.
Polarizer Most useful. For photo taking through glass, it minimizes
surface reflections off glass and water. Also causes increased
saturation of colors and performs interesting magic with
contrast. Must be used with the sun either to your left or
right side - any other orientation diminishes filter
effectiveness. 1 to 3 stop filter factor. Note: some polarizers
are variable density.
Film Selection
To obtain the best possible results in the pictures that you take, select your film
carefully. Know the conditions you will be shooting pictures under and let this be your
guide to film selection,
• Where light levels are low. ..
• Where subjects are in motion.. .
• Where subjects are dark in tone or color ..
• Where telephoto lenses must be used.. .
Then select the fastest film you feel will capture the needed image. There are
tradeoffs: the faster the film, the poorer it's ability to resolve fine detail, and the less
margin for exposure error.
The slowest film having useful speed for these kinds of situations is Ektachrome 200.
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Here are some other fast film choices for you to consider:
Tri-X black and white film rated at AS A/ISO 400; can be
used up to AS A/ISO 1600 with special development.
Ektachrome 400 color film rated at AS A/ISO 400; can be used up to
AS A/ISO WOO with special development. Notify
Kodak if special development is required by using their
ESP-1 processing envelope.
Ektachrome 800-1600 color film with variable AS A/ISO. Kodak must be
informed as to ASA /ISO actually used.
color film. Expensive.
color film. Also expensive.
Kodacolor 400
Kodacolor 1000
NOTE: When a film is identified by use of the word 'chrome' in it's name, that film is
a color transparency or slide film. When the film's name includes the word 'color,' the
product is a print film. Ektachrome films have the advantage, along with kodacolor films,
of being suitable for local processing within short time spans. Both print films have the
ability to be used under available light from different sources without corrective
filtration.
• Where light is of sufficient brightness...
• Where subjects motion is slower paced...
• Where subjects are average or above average in brightness..
• Where detail rendition must be excellent...
Then select one of the slower films, such as:
Kodachrome 25
Kodachrome 64
Ektachrome 64
Kodacolor 100
Panatomic X
Tech Pan 2415
color film. It is the slowest speed color film Kodak
offers, and has the highest resolution of all Kodak
color films.
color film. A bit more than one stop faster than
AS A/ISO 25 film, this product is a/most as good.
color film. Closely duplicates Kodachrome 64. Offers
rapid processing turnaround time.
color film. Has the highest resolution of all Kodak color
print films. Expensive. Shares same lighting flexibility
as its faster relatives.
black and white film. ASA/ISO 32. Has the highest
resolution of the conventional Kodak b&w films.
black and white film. AS A/ISO 25. A special film,
requiring special development. Essentially grain free.
Any of these slower films will work well in daylight out-of-doors situations. Where
lower light levels are involved, or when the use of telephoto lenses is desired or
necessary, a tripod or good steady rest would be essential.
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