1 What is Photography?
Answer: an art, and certainly is a science of producing an image by the action of light on light – sensitive substances (silver halides) and by the application of several chemicals and physical laws.
2 What is vital to photography?
Answer: Light, for it is the physical means used to produce the image. without light, there will be no image.
3 What are the CLASSIFICATIONS OF LIGHT?
Answer: Light, as a form of radiant energy, is classified according to wavelength and frequency.
4 What is WAVELENGTH?
Answer: Wavelength is the distance between any two such identical points in a given instant of time. Since the electromagnetic spectrum is arranged according to wavelength, there must be measurement of this length. The length of light waves is measured from a point on one crest to an identical point on the next crest.
5 What is FREQUENCY?
Answer: The frequency of light is the number of complete waves that would pass a given point in a second time. The longer the wavelength, the fewer the number of waves that will pass a point in a second or the longer the wavelength the less the frequency; the shorter the wavelength the greater the frequency.
6 What is the COMPOSITION OF WHITE LIGHT?
Answer: White light is composed of all visible light wavelengths in the visible spectrum. Sunlight is white and is an ideal or equal blending of all the wavelengths of the visible spectrum. If any of these wavelength are missing, even in part, we have another color instead of white light.
7 What is OPTICS?
Answer: Optics is a branch of science concerned with the behavior of light.
8 What are the basic characteristics of light behavior which we used to see and to produce photographic image?
Answer: they are:
° REFLECTION. Any object that is non-luminous, that does not itself emit light, can be seen only by reflected light that has originated at a luminous source. All objects reflect some light and absorb some. Glass mirrors, polished metals, white papers, all reflect most of the light and absorb some. Black objects absorb most of the light and reflect very little. Light that are either absorbed or transmitted, that is, when light passes
through a medium such as glass or any transparent substance.
° ABSORPTION. Light will normally be absorbed to some degree no matter what type of surfaces is encountered. The color of the object is largely a matter of absorption and reflection. When white light falls on an object that absorbs some of the wavelengths and reflects and transmitted others, the object appears to have color. The wavelength that is reflected or transmitted determines the color of the object. For example, a red object appears red because it reflects or transmit only the red wavelengths. The others which is green and blue, are absorbed by the object.
° REFRACTION. When light strikes the surface of opaque objects some is absorbed and some is reflected. But when it strikes an object which is transparent, such as glass, a little light is absorbed. These penetrating rays, however, have quite probably undergone some changes; they have been bent. The bending or deflection is what is termed as refraction.
9 What is the LAW OF REFRACTION?
Answer: “If a light rays hit perpendicular to the surface between two mediums of different density, the ray is not bent. If the light strikes the surface at an angle, the ray will be bent. The direction in which the light is bent is dependent upon the density of its mediums the light is traveling to”.
10 What is INDEX OF REFRACTION?
Answer: Light travels at varying speeds. The speed of light in air or vacuum is approximately 186,000 miles per second while in some glass is approximately 124,000 miles per second. Using the two figures, the refractive index of the glass would be 1.5 (124,000 divided into 186,000). The refractive index of water is about 1.3. the refractive index is never less than 1 and rarely more than 2. The higher the index number, the greater the light – bending power of the
substance. A practical use of this knowledge is in the determination of the angle of refraction of lenses made for various types of glass and use for varying purposes.
11 What is CAMERA LENSE or OPTICS?
Answer: A camera optic or lens, is a spherical and symmetrical piece of polished glass. The purpose of which is to gather, refracts and project light ray on the rear wall of the camera and to produce a clear, sharp image.
12 What is the effect If a film is placed in front of the wall opposite the pinhole?
Answer; the negative image that appears after the film if develop will not be very sharp, but it will be quite recognizable as an image of the subject at which the pinhole was aimed. It will not be sharp because the pinhole actually lets in more than one ray of light from each point on the subject and these rays do not strike at exactly the same point on the film. If the pinhole sized is decreased to reduced image blur, it requires also a long exposure time ( which is already long). In addition a very tiny pinhole tends to scatter the light rays and thus image blur actually increases.
13 How to accomplish a brighter and sharper image? Answer: Both can be accomplished by reflecting or refracting the light so that it can collect great bundles of light rays from a single point and redirect them all to meet again at another point – on the film.
14 What part of a camera usually has a function of reflecting or refracting the light so that it can collect great bundles of light rays from a single point and redirect them all to meet again at another point – on the film?
Answer: the camera lens.
15 What is the effect if the distance between lens and subject is shortened?
Answer; if the distance between lens and subject is shortened, the distance between lens and film is extended. This of course, the adjustment being made when focusing the camera; the lens is moved away from the film for close subjects and moved towards the film for distant subject.
16 What are the TYPES OF SINGLE SIMPLE LENS?
Answer: Simple lenses are classified according to the way in which they bend the rays of light falling upon them. They are divided into two groups:
° Positive lens/ Convergent lens. Basically these lenses are thicker at the center than at the edges. Tehse lenses from real images because light rays passing through them converged, that is, the rays leaving the lens are bent inward and toward one another and so eventually meet (focus). Lens in this class are also termed convex, convergent, or collective. The most common positive lens is the double convex which will cause light rays from either side of the lens surface, to converge. All these lenses have at least one convex surface, that is, a surface that curved outward.
° Negative lens. These lenses are thicker at the ends than at the center and have at least one concave surface. These lens called concave divergent, or dispersive. Light rays that passed through them are spread apart, negative lenses are not used alone but they from part of a compound lens to correct for errors or distortion.
17 What is meant by Focal Plane of a lens?
Answer: The focal plane of a lens is the plane where the lens projected image which is clear and sharp. This plane is sometimes called the film plane, as the film is located at this point to capture the image.
18 What is meant by Focal Length of a lens?
Answer: Focal lengths can be defined as the distance from the lens to the point at which
light rays that entered the lens on parallel paths will be brought to focus. If the camera lens is focused at infinity which in practical terms means focused on a subject a great distance away (200 feet or more), the light rays reflected by that subject will be traveling on parallel paths, for all practical purposes, when they reach the lens. So the definition of focal length is often given as the distance between the lens and the film when the lens is focused at infinity. The photographer seldom or need no measure the focal length of a lens for this characteristic is almost always marked on the front of the lens mount, in millimeters or in inches.
19 What is the importance of Focal Length of a lens? Answer: The focal length of a lens controls the image brightness, speed of the lens, and the image size at the focal plane. It is a fixed value of the lens and cannot be varied by the photographer. Also, it is inherent factor of the lens which is controlled by the thickness of the lens and the curvatures of its surfaces.
20 What is the best tool for learning to use of lenses?
Answer: A 35 – mm single lens reflex camera is the best tool for learning to use of lenses of varying focal lengths because you can actually see what the lens is putting in your picture frame. The picture can be studied in the finder, observe the relative sizes of images within the picture’s depth.
21 What is Lens Speed?
Answer: it is the largest opening of the diaphragm (aperture) at which a lens can be used. “Speed” here refers to intensity of the light reaching the film, and not to any movement. Thus an f/2 lens is faster than f/4 because an f/2 has a wider aperture and will admit more light at a given time.
Answer: Lenses having a large aperture are called “fast” lenses because their large aperture makes it possible to take photographic at a very short exposure interval or under very dim light conditions. The closer this widest aperture comes to 1, or to being equal in diameter to the focal length of the lens, the faster the lens.
23 What is the practical application of a fast lens? Answer: the practical application of a fast lens is when the light level of a scene is very low, such as in a night club scene. In short, the faster the lens, the lesser the amount of light needed to reproduced an image
24 What is camera shutter?
Answer; A mechanical device used to control the duration of the time interval during which light will travel to act on the film. It is an adjustable mechanism that regulates the amount of light reaching the film by varying the length of time light is allowed to pass through the lens. 25 What is Focal Plane Shutter?
Answer: Focal Plane Shutter is also known as curtain shutter consist of a lightproof rubberized cloth curtain having rectangular openings or slits usually arranged to move horizontally/ or vertically in some cameras. It house entirely within the camera body and is mounted in two rollers. When an exposure is made, the leading curtain moves, say to the right, uncovering the film so that light can act upon it. At the end of the exposure interval, curtain moves to the right to cover the film surface once again.
26 What is the advantage of Focal Plane Shutter?
Answer: The advantage of this type of shutter is to allow the lens interchangeability and it has a high shutter speed up to 1/1000 of a second.
27 What is the disadvantage of Focal Plane Shutter? Answer: where critical measurements in motion are required, this shutter is undesirable because
of image distortion. At the instant, the fast moving subject may appear elongated or shortened than it actually is, depending on the direction of motion.
28 What is Shutter Speed
Answer: Shutter speed refers to the time that the shutter is opened, following light to reach the film. The interval during which it is desired for the shutter to remain open is selected by rotating the shutter speed dial and setting it on the desired scale.
29 What is usually the shutter-speed scale marking? Answer: The camera’s shutter-speed scale markings are usually T, or D, 1, 2, 8, 15, 30, 60, 125, 250, 500, 1000, and / or even 2000. The first number in this series stands for 1 full second, but all other number are fractions of a second, 2 is for ½ second, 4 is ¼ second and so forth. The scale may vary from this example, depending upon the camera but each shutter setting gives one half of the time of the preceding number and twice of the succeeding one. All these numbers are abbreviated expressions for fractions of a second and denote shutter speed.
30 What is the “B” setting stands for?
Answer: the “B” setting stands for “bulb” – a word that goes far back into camera history. Used for exposure longer than one second. Pressure on the shutter release button will open the shutter and will remain opened as long as pressure is maintained. But once pressure is released, the shutter closes again.
31 What is the “T” setting stands for?
Answer: the “T” setting stands for “time “time” like the “bulb” setting the “T” setting is also used for time exposure of more than one second . It differs from the bulb setting only in that the shutter release button does not have to have held down to make an exposure. Pressure on the button causes the shutter open. It will remain open
until the shutter releases button is pressed a second time to close it.
32 How to Photograph a Moving Object?
Answer: When an object is in motion during exposure, its image on the film also moves, even though the duration of exposure (shutter speed) is 1/1000 of a second, the images moves a small fraction of an inch during this time. The problem for the photographer, then, is to determine just how much image movement can be tolerated before it becomes objectionable and regulate the shutter speed accordingly. As a general rule, the permissible image movement (circle of confusion) is 1/1000 of an inch if they are to be enlarged. 33 What are the four factors which determine the
distance of an image moves on the film during exposure?
Answer: The four factors which determine the distance of an image moves on the film during exposure are:
a The object distance (from lens to object) b The image distance (from lens to film)
c The speed of the object (perpendicular to lens axis)
d The interval of the exposure
° The first three factors determine the speed at which the image moves across the film and the fourth simply limits the times it is allowed to move, thereby limiting the distance of image movement.
34 What is the use of LIGHT METER OR EXPOSURE METER? Answer: These meters measures the incident light falling upon or the light reflected from a photographic subject, and provide means of converting this information into useable shutter speed and stop. However, this aid is mainly used as a guide, the final interpretation of lighting and camera factors, and picture requirement for best exposure is the decision of the photographer.
35 How to know the EXPOSURE without the built-in LIGHT METER of a camera?
Answer: cameras which do not have built-in light meters, exposure is determined by following the manufacturer’s suggested general guidelines supplied with the film, and then ISO (formerly ASA/ DIN) scale on the camera film speed dial series simply as a reminder. Exposure can be done by using the speed number of the film as the initial shutter speed on the camera; 1/100 of the second shutter speed for ASA/ 100 film; 1/400 for a second for ASA/400 film, and so forth. Set the film as close as can be on the shutter speed dial, 1/125 for ASA/100; 1/500 for ASA/400 and so forth. Then set the f/number according to the class of lighting condition common throughout photographic literature, and, in most cases, are used in the film as an aid in determining exposure. The information sheet is only a guide; it does not guarantee perfect exposure. Variables not adequately considered are: time of the day, time of the year, geographical location, direction of the light, and type of the subject. 36 What are the different TYPES OF DAYLIGHT
ILLUMINATIONS? Answer:
° Bright Sun. The sky is clear, bright, and free of large cloud masses or atmospheric haze. Any shadows cast by the sun are sharply defined. An ideal photographic condition.
° Hazy Sun. The sun is partially obscured by clouds or haze, the edges of shadows are slightly diffused or set and are less clearly defined than those in bright sun.
° Cloudy Bright. The sun is largely obscured by clouds or haze. The sun is in evidence, but the shadow are not apparent. This daylight condition exists when the light is bright even glaring and it seems there should be shadows but there are few, if any.
° Cloudy Dull. The sun is completely obscured by heavy layers of clouds or dense haze. Light is completely diffused and it is
difficult to determine the exact position of the sun.
37 What are the different TYPES OF SUBJECT BRIGHTNESS?
Answer:
° Dark Subject. Dark subjects reflects only about 9 percent of the light striking it and absorbs the remainder. Included in this category are vehicles and weapons, people in dark-toned clothing etc.
° Average Subject. Is one that reflects approximately 18 percent of the light striking it and absorbs the remainder. Examples are people in medium-colored clothing, most buildings, street scenes, and interior views.
° Bright Subject. Reflects twice as much as an average subject. Typical subjects in this category are a fair-skinned and light- haired person, people in light clothing, and light-colored buildings.
° Brilliant Subject. A brilliant subject reflects about four times as much light as an average subject and absorbs very little light, some of this subject are people in light – colored clothing on a white and sandy beach, a white sailboat against a blue sky and white buildings of a desert village.
38 What are the different REFLECTIVE POWER OF COLORS?
Answer: The following list are the approximate percentage of light that is reflected by some colors, white (75%), chrome yellow (62%), cardinal red (27%), pearl gray (75%), cream (62%), brown (27%), satin green (75%), sky blue (62%), maroon (27%).
39 What is meant by “FOCUS “in a CAMERA LENS FOCUS? Answer: focus a lens means to concentrate light rays on one particular surface, which, in a camera, is the surface of the film.
40 What is focal point?
Answer: focal point is the point where one’s visual attention becomes focused, and the point on the film’s surface where the entire light ray concentrate or intersects is known as the point of principal focus.
41 What is FOCUSING RING?
Answer: The focusing ring is large knurled ring around the barrel of the lens that operates on a type of screw-thread mechanism. When turned, the lens will either moves away or toward the camera body, depending upon the direction of rotation.