FP FINALS

Focusing

Is the process of changing the distance between the centers of thelenstothefocal plane. It is the technique of adjusting the focal length toget thesharpimage of the object or scene to be photographed

Focal Length

is the distance between the focal point of a lens and the film plane when the lens is focused at infinity

Focal plane

is the area inside any camera where the individual frame of film or digital sensor is positioned during exposure

Focal point

The central or principal point of focus. The optical center of a lens when it is focused on infinity.

Infinity

Refers to the distance so far removed from the observer that the rays of light reflected to a lens from a point at the distance may be regarded as parallel. It is a distance setting on a camera focusing scale, beyond which all objects are in focus.

Real Focus

The point of convergence of the light rays.

Virtual Focus

The point where diverging rays would meet if their direction were reversed.

Depth of Focus

A zone of focus in the camera. If an image is focused on a ground glass screen in a camera, makes it possible to move the screens slightly backward or forward and still have the image in acceptable

Depth of Field

The amount of area in focus. • It is the distance from the nearest object in good focus to the farthest object in good focus.

Deep Depth of Field

- A large area in the image is in sharp focus, from the foreground to the background.

Shallow Depth of Field

- Only a small part of the image is in sharp focus, while the rest is blurred

Shorter focal length lens

(Example: A wide-angle lens (e.g., 18mm)hasagreater depth of field than a telephoto lens (e.g., 200mm).

Smaller lens aperture

(A smaller aperture allows less light and increases the area in focus)

Greater subjects distance

(The farther the subject, the deeper thedepthoffield)

Longer focal length lens

(Example: A telephoto lens (e.g., 85mm, 200mm) has a shallower depth of field than a wide-angle lens (e.g., 18mm)

Larger lens aperture

(A wider aperture lets in more light and creates a wider focus area.

Shorter subjects distance

e (The closer you are to the subject, theshallowerthedepth of field).

Greater/Deep depth of field

More sharp detail is visible

Auto Focus

The predominant type of lenses on the market. • It focuses using a phase detection system that splits the incoming light into two or more parts and compares them to determine the amount of defocus.

Manual lenses

You use it by turning the focusing ring by hand until the subject is sharpintheviewfinder.

Parallax

Is the term used to describe the difference between the image as seen by a viewing system and the image as recorded by the sensor. Variance occurs as subjects move closer to the lens. Only through the lens viewing system avoid parallax error.

Shutter

Is a mechanism that opens and closes within the camera to provide the time interval necessary for exposure.

Exposure

Is subjecting the light-sensitive material to light in order to form an image (initially a latent image). This involves controlling the right amount of light and time to achieve correct exposure.

\The product of illumination and time

Latent Photographic Image

– . This image conforms to the shape of the object points in the subject according to the capability of the lens and film.

Exposure Triangle

is a combination of three camera settings that control how much light enters the camera's sensor

Reflected light readings:

Measure the light coming off the subject. (Pointingthe metering cell toward the subject)

Incident light readings:

Measures the light falling on the subject. (Pointthemeter back toward the light source)

Spot metering

: basically the same as reflected light meters but theymeasurelight from a very selective area

Averaging meters

are most sensitive at the center of the screen, but they nevertheless give an integrated reading over the entire picture area.

C e n t e r - w e i g h t e d m e t e r s

have concentrated sensitivity at or near the center, but take some account of the rest of the picture area.

Spot metering

are limited to a small area.

Flash Unit

– are source of additional illumination in lowlighting conditions

Filters

- transparent material usually colored (glass or gelatin), fitted to a lens to alter the characteristics of light passing through it

Synchronization speed

Is the fastest shutter speed that can be used with an electronic flash.

Shutter Speed

Aside from controlling the amount of time the shutter also controls motion or action

Reciprocity Law

States that to get a certain amount of exposure on film, no particular amount of light and no particular length of time is required. The requirement is that the amount of light is multiplied by the length of time must equal the desired exposure

Lens Speed

It also indicates the capability of the lens to gather more light in lowlight conditions.

Conversion Filters

This changes the color balance of light for a given film. For example,tungsten films are designed and balanced for the color temperature of aluminum tungsten light. Exposed to daylight, they will produce pictures with a bluish cast. A Series 85 conversion filter can correct this. Improving Forensic Photography: It helps ensure evidence photos have true-to-life colors for accurate analysis.

Light Balancing Filter

These are generally used to make small adjustments in color. These pale-toned filters eliminate undesirable colorcasts or add a general warming hue. Forensic Photography Applications: Ensures crime scene images capture true colors for accurate evidence documentation

Polarizer/Polarizing Filter

This is primarily used to reduce reflection from the surface of shiny subjects. These are also used in color photography to increase color saturation. Revealing Hidden Details – Used in forensic photography to see through glare on wet surfaces or shiny objects.

Color Filters

These are used to control the relative tone values in which colors are rendered by the photographic process, to lighten or darken particular colors, or to obtain color separation records for color photography works.

This may be defined as an optically homogenous filter in which the absorption of light and transmission of light vary with the wavelength.

blue filters

This can be used effectively when photographing blood in black and white. When used outdoors, it will make the sky or any blue object appear white in photography.

Green Filters

now used in photographing blood.

Yellow Filters

cuts through haze to a certain extent and can be used with good result to photograph an accident on a hazy day.

Viewing Filters

These are designed to show by direct observation the relative values in which colors will be reproduced by a particular type of sensitized material with or without a given filter. Ensuring Accurate Evidence Documentation – forensic photographers to preview how different filters will affect color and tone.

Natural Density Filters

These are used to reduce the amount of light passing through the lenses without altering brightness relationships within the scene. filters reduce the amount of light passing through a camera lens without changing the reproduction of colors in the scene.

Polarizing Filters

I t r e d u c e s o r e l i m i n a t e s

unwanted reflections (glare) from

nonmetallic surfaces, such as glass

and water, effects exposure control

(similar to ND filters), may darken

the blue-sky image in both black

and white and color photography

and may increase color saturation in

a color photograph without altering

the hues of image colors

Correction Filters

This renders colors in the scene in shades of gray that correspond to their perceived relative brightness.

Contrast Filters

This increases gray tone separation between two colors that might otherwise appear of the same tonal value.

Haze Filters

This reduces aerial haze in distance and serial shots. This includes contrast and correction filters. Although contrast filters can be used for cutting haze, these filters affect the gray tone rendering of colored objects. The contrast and correction filters that absorb the shorter wavelengths are most effective.

Skylight or ultraviolet Filter

This filters out UV light, reduce haze and increase the color saturation of the sky and t o r e d u c e t h e e f f e c t o f excessive blue light at high altitudes and on overcast days.

Color compensating Filters

This filters precisely alters the color balance of any source of light during shooting or printing to achieve any combination of primary and secondary wavelengths desired.

Aberration

is the failure of light rays to focus properly after they pass through lens or reflect from a mirror. Proper focus occurs when the lightrays cross one another at a single point. occurs because of minute variations in lenses and mirror, and because different parts of the light spectrum are reflected or refracted by varying amounts.

also defined as an optical imperfection responsible for image distortion. It can be avoided by combining several lenses and by elimination of marginal rays refracted through the outer edge soft lenses.

Spherical Aberration

is the focusing at the different parts of spherical lens. This aberration occurs because light hitting the outer parts of the lens is bent more sharply and comes to a focus sooner than that passing through the middle. In spherical aberration, the image is blurred because different parts of a spherical lens or mirror have different focal lengths.

Chromatic Aberration

All lenses (single) made of one material refract rays of short wavelengths more strongly than those of longer wavelengths and so bring blue or more to a shorter focus than red. The result is that the image of a point white light is not a white point, but a blurring circle bordered with colors.

is the failure of different colored light rays to focus after passing through a lens focusing of light of different colors at different points resulting in a blurred image. When white light, which consists of colors, passes through a lens, the bend the rays. The rays then cross one another on the other side.

Astigmatism

is the defect in which the light coming from an off-axis object point is spread along the direction of the optic axis. If the object is a vertical line, the cross section of the refracted beam atprogressively greater distances from the lens is an ellipsethat that collapses first into a horizontal line, spread out again, andlater later becomes a vertical line

is the failure of a lens to produce a point image of an object point. Such condition occurs when the lens surfaces are not symmetrical with respect to the principal axis of the lens. An extreme example would be one surface is spherical and the other is cylindrical, or when the lens surfaces are perfectly spherical but the beam of light from the object point passes through the lens very obliquely

the image appears elliptical or cross s h a p e d b e c a u s e o f a n irregularity in the curvature of the lens. This is the inability of the lens to bring horizontal an d v e rti c a l l i n e s i n t h e subject to the same plane focus in the image.

Coma

a is a pear-shaped image of small circle or point near the edges of the image plane. The result of which is an overall spot that is comatic in shape, having bright central core with a flare extending toward the optical axis of the lens.

a occurs when light falling obliquely on the lens and passing through different circular zones is brought to a focus at different distances from the plane film. A spot of light appears to have a tail, rather than a comet. In coma, the images appear progressively elongated toward the edge of the field of view.

AlexisClairaut

The term Coma was coined in 1733 by French mathematician

Curvature of Field

concave, or saucer-shaped image of an object that has a flat surface produced by a simple lens.

\the relation of the image of the different points are incorrect with r e s p e c t t o o n e a n o t h e r. I n curvature, the images of the different points of the plane image lie on a curved surface with points at the edge of the field lying nearer to the lens than those at the center. In curvature, the images distance is different for different points of the same object due to their differing distance from the axis

The fuzzine ss inc r e a s e s toward the edge of the film. Refocusing brings different circle into focus but others now are blurred.

Distortion

arises from a variation of magnification with axial distance and is not caused by a lack of sharpness in the image.

Flare

is a non-image-forming light. Reduces contrast and color saturation. is caused by very light subjec t areas and produces internal reflections in the lens. Stacking of filters can increase flare. Lens coating by the manufacturer keeps flare to a minimum. The use of a suitable hood (not the stock hood) can also aid in reducing flare.

can show up as a plain area of unwanted bright light or in shapes matching the aperture

Mechanical Flare

These are bright spots on the film caused by stray light fromwornshiny parts of the lens such as the stop, shutter lens mount, orfromthe camera itself.

light loss

Most covered lenses is coated with a substance that will reduce one type of flare (optical) and which will also increase the optical ability to transmit light thus reducing

Strat light

This can be reduced or eliminated by using the proper lens shade placed on the front of the lens as shield.

Ghost Image

Is a result of double reflection from inner lens surfaces. It exhibits itself as a misty haze, or a cloudy semicircular patch of light which may cover part or all of the image. This cloudy reflection may form an image called a

Red Eye

An image in which a subject's irises are red insteadof black. The eye effect is caused by light from a flash travelling through theiris and illuminating the retina at the interior back of the eye, which is retinal due to its blood vessels and the camera capturing that redness on film

is the phenomenon where people have glowing red eyes in photographs. This is caused by the close proximity of the flash (especially the built in flash) to the camera lens, which causes light from the subject to be reflected directly back at the camera. When the flashfires, the light reflects of the blood in the capillaries in the back of the subject's eyes and back into the camera lens. People with blue eyes are particularly susceptible to red eye phenomenon because they have less pigment to absorb light.

Red Eye Reduction

A feature of some cameras or flash units that is meant to reduce the effect of red eye by emitting multiple bursts of light immediately before the picture is taken. The intended result is a forced reduction in the size of the subject's iris

A more effective method is to use an external flash via the camera's shot-shoe mount or, better yet, with an extension bracket. An external flash radically changes the reflection of the blood in the back of your subject's eyes.

There are a few ways to minimize or eliminate red-eyeinyourpictures. Some cameras provide a red-eye reductionfeaturethatfiresa preflash, forcing the irises in your subject's eyes toclosebeforeyoutake the picture. The main problem with this methodis thatitoftenforces subjects to involuntary close their eyes beforetheimageistaken, and it doesn't always completely eliminate the red-eyeeffect

Dark Room

Is a place where the entire photographic process which consists of the development of the printing of photographic filmis is performed, is nothing more than a room capable of being "blackened out or completely darkened.

Processing Photographic Film

The processing of photographic filmis that treatment of it with chemical solutions that causes the image to develop out a negative

Developer

amplifies the exposed latent image in the film or paper and creates a visible image. It turns the exposed silver halidestometallic silver.

Stop Bath

an acid solution that halts the developing process.

Fixer

removes the unexpected silver halides and fixes or makes the image permanent.

65 degrees Fahrenheit

is the ideal temperature of the developer.

Agitation

- is the process of keeping the chemicals (developer, stopbath, or fixer), in a mild even motion while paper is being processed. This is necessary to prevent spotting, streaking of the finished print.

Alternate light sources (ALS) -

such as lasers, blue or green lights and colored filters that help detect processed latent fingerprints or other hidden evidence and illuminate for photographing.

Oblique angle lighting

– using a flashlight, camera flash or ALS at a very low angle to cast shadows that allow an imprint o r i m p r e s s i o n t o b e photographed

Macro lenses

can take very close-up images (1:1 or 1:2) of small items such as tool marks or trace evidence.

technical photography

The type of style of photography used in photographing crimes cenes and evidence is called

\

are photographs that show as as much detail information about the view or object as possible