quiz three photography

Understanding what your built in meter is telling you

-2..1..0..1..+2 -2 - 0 is underexposed 0 - +2 is overexposed

Equivalent exposure

-suppose an exposure for a scene is 1/60 sec shutter speed at f/5.6 aperture -Using any one of the combinations below will give you the exactly same exposure shutter speed: 1/8 and Aperture F/16 Shutter speed: 1/15 and Aperture F/11 Shutter speed: 1/30 and Aperture F/8 Shutter speed: 1/60 and Aperture F/5.6 Shutter Speed: 1/125 & Aperture F/4 Shutter speed: 1/250 and Aperture F2/8

Exposure meters

-vary in design,but they all perform the same basic function -they measure the amount of light -then, for a given sensor or film sensitivity ISO, they calculate f-stop and shutter speed combinations that will prodduce a correct exposure for a scene tht has an average distribution of light and dark

The rule of thirds

The theory is that if you place points of interest in the intersections or along the lines that your photo becomes more balanced and will be enable a viewer of the image to interact with it more naturally. Studies have shown that when viewing images that people's eyes usually go to one of the intersection points most naturally rather than the center of the shot. In the rule of thirds, photos are divided into thirds with two imaginary lines vertically and two lines horizontally making three columns, three rows, and nine sections in the images. Important compositional elements and leading lines are placed on or near the imaginary lines and where the lines intersect.

How do you bracket?

To bracket, you make several photographs of the same scene, increasing and decreasing the exposre by adjusting the aperture or shutter speed. Among several different exposures, there is likely to be at least one tha is correct. It is not just beginners that use bracketing, professional photographers often do it as protection against having to repeat a whole shooting session because none of their exposures was quite right.

Underexposed

To make an exposure with too little light, producing a photo that is too dark

Center-weighted Meter

Favors the light level of the central area of an image, which is often the most important one to meter. Cameras with built-in meters usually use some form of center weighting

Bracketing

Taking several photographs of the same scene at different exposure settings, some greater than and some less than the setting indicated by the meter, to ensure at least one well-exposed frame. The shutter speed remains the same, but the aperture changes to let in one more stop of light and one less stop of light

ISO setting on a digital camera

will change either the aperture or shutter speed but will not make the picture lighter or darker. Instead you will need to use the button, dial, or menu item that controls exposure compensation. You can set the ccamera to expose all your photos at a fixed amount more or less than the meter indicates, or you can make an exposure change for one picture at a time

ISO settings

100 = outside on a sunny day 800-1000 = outside in partial sunlight/shade 1600 = indoors at a birthday party with minimal available light

exposure =

Intensity X Time

Meters are designed to measure

middle gray

Exposure compensation dial

Moving this dial to +1 or +2 increases the exposure by one or two f-stops and lightens the picture. Moving the dial to -1 or -2 decreases the aperture and darkens the picture

One stop less exposure

darken the scene

A reflected-light meter averages

the light entering its angle of view. The meter is calibrated on the assumption that in an average scene all the tones or values - dark, medium, and light - will add up to a medium gray. So the meter and its circuitry set, or reccomend, an exposure that will record all of the light reflectances that it is reading as centered around a middle gray. This works well if you are photographing an average scene (light is coming more or less behind you or when the light is evenly diffused over the entire scene

ISO Speed

(100, 200, 400, and so on) describes a sensor's sensitivity to light. The higher the number, the less light it needs for the correct exposure (one that is not too light or too dark). With a digital camera, you may select ISO setting within that camera's range. You may choose a different ISO for each picture. Lower numbers will generally result in higher-quality pictures. Set an ISO of 100 to 200 for shooting outdoors in sunny conditions. In dimmer light such as indoors use an ISO of 400 or higher. Film is made with a fixed ISO; an entire roll must be exposed at that speed.

Scenes that are light overall

(snow scene) can look too dark in the final photograph if you just make an overall reading or let the automatic camera make one for you. The reason is that the meter will make its usual assumption that is pointed at a scene consisting of light, medium, and dark tones (one that averages out to middle gray) and it will set the aperture accordingly. But this will underexpose the scene that consists of mostly light tones, called high-key, resulting in a too-dark photo. Try giving one or two stops extra exposure

Why do we use equivalent exposures

-to artistically alter the appearance of our images, while still using the correct exposure. SUCH AS depth of field and to freeze or blur motion

ISO

-your camera's sensitivity to light - higher ISO settings are generally used in darker situations to get faster shutter speeds (for example an indoor sporting event when you want to freeze the action in lower light)

Situations where you might need to push ISO to higher settings include:

1. Indoor sporting events: where your subject is moving fast yet you may have limited light available 2. Concerts: also low in light and often 'no-flash" zones 3. Art Galleries: Churches etc. many galleries have rules against using a flash and of course indoors are not usually well lit 4. Birthday parties: blowing out the candles in a dark room can give you a nice moody shot which would be ruined by a bright flash. Increasing the ISO can help you capture the scene.

Which two genres of photography do you think it would be most beneficial to adjust your white balance

1. food photography 2. Portrait photography

Exposure Meters and their functions

Despite the fact that they vary in design, they all perform the same function -They measure the amount of light for a given sensor or film sensitivity (ISO) -They Calculate f/stop and shutter speed combinations that will produce a correct exposure for a given scene that has an average distribution of light (average = equal dark, equal light)

Backlight button

If a camera does not have an exposure compensation dial, it may have a backlight button. Depressing the button adds a fixed amount of exposure, 1 to (1/2) stops, and lightens the picture. It cannot be used to decrease exposure

Overexposed

To make an exposure with too much light, producing a photo that is too light

When do you use bracketing

Use when a scene is not average and when you are not sure about the exposure

Manual mode

With an automatic camera that has a manual mode, you adjust the shutter speed and aperture yourself. You can increase or decrease the exposure as you wish.

Longer exposures increases noise

You use a long exposure when very little illumination reaches the sensor - perhaps because of a very small aperture or a dimly lit subject. HDR photographs because of the great range of brightness are often dimly lit in the darker areas and require longer exposures. One kind of noise, heat generated electrons called dark noise, accumulates over time and so forms a more noticeable part of an image made with long exposure.

Through the lens meter (TTL)

built into the camera, shows in the camera's viewfinder the area that the meter is reading. Usually coupled to the camera to set the exposure automatically.

ISO setting on a film camera

doesnt change the light sensitivity of the film, so you can change the exposure by changing the film speed settting if the camera allows you to set ISO manually. ISO 100 to ISO 200 darkens the picture by increasing the exposure one stop ISO 400 to ISO 200 lightens the picture by increasing the exposure by one stop

When are changes in ISO very noticeable

especially when texture is the main element of your photo

White balance

helps add the proper coloring to your photos based on the type of light you are shooting in

Higher ISO settings

increases Noise. A photosite does not change its sensitivity - the way it responds to photons falling on it by collecting and counting electrons- when you adjust the ISO number to a higher setting. circuitry amplifies data. Higher ISO you shoot smaller aperture or higher shutter speed so the sensor receives less illumination overall. The kinds of noise that are always present at low level are then amplified more than they would be at a lower ISO and form a more noticeable part of the image

A multi-segment meter

is the most sophisticated of the meters built into a camera. It divides the screen into areas that are metered individually, then analyzed against a series of patterns stored in the camera's memory. The resulting exposure is more likely to avoid problems such as underexposure of a subject against a very bright sky.

You can make some adjustments in tone

later when you edit your pictures, but good results and the effect you want are easier to get if you first use the camera to capture the correct exposure. Bracket your exposures if you are not sure and especially if you notice the scene is not average (equally light and dark) If your camera is capturing TIFF or JPEG files you have a little leeway.Shooting camera Raw files gives you a better chance at retrieving an image that was slightly over or underexposed

Scenes that are dark overall

less common, but do occur. When the meter sees an entire scene that is very dark, called low-key, it assumes it is a dimly-lit average scene and lets in more light. If your main subject is not as dark as the background, it will render too light. Try reducing the exposure one or two stops

An average or overall meter

reads most of the image area and computes an exposure that is the average of all the tones in the scene. A hand-held meter, typically makes an overall reading

To Bracket, first

make an exposure with the aperture and shutter speed set by the automatic system or manually set by you at the combination you think is the right one. Then, make a second shot with one stop more exposure and a third shot with one stop less exposure. This is easy to do if you set it manually: for one stop more exposure either set the shutter to the next slower speed or the aperture to the next larger opening (the next smaller f-number). For one stop less exposure, either set the shutter to the next faster speed or the aperture to the next smaller opening (the next larger f-number).

All a meter does is

measure light. It doesn't know what part of a scene you are interested in or whether a particular object should be light or dark. You have to think ahead of the meter and sometimes change the exposure it recommends.

Handheld meters

measure reflected light or incident light. When the cell of a hand-held meter is exposed to light, it moves a needle across a scale of numbers or activates a digital display.The brighter the light, the higher the reading. The meter (set for ISO) then calculates and displays recomended f-stop and shutter-speed combinations

An incident-light meter

measures the amount of light falling on it - and so, the amount of light falling on a subject in similar light. To make a reading, point the meter away from the subject, toward the camera.

A reflected light meter

measures the amount of light reflected from an object. It can be held (left) or built into a camera. To make a reading point the meter at the entire scene or at a specific part of it

What do you need to produce a good exposure

meters

Exposure lock

or memory switch, temporarily locks in an exposure, so you can move up close or point the camera in a different direction to take a reading of a particular area, lock in the desired setting, step back, and then photograph the entire scene.

Many cameras with automatic exposure have a means of

overriding the automatic system when you want to increase the exposure to lighten a picture or decrease the exposure to darken it.

Calculating exposure of an average scene with a hand-held reflected-light meter

page 65

Calculating exposure of an average scene with an incident-light meter

page 65

Using a meter built into a camera for exposure of an average scene

page 65

A spot meter

reads only a small part of the image. Very accurate exposures can be calculated with a spot meter, but it is important to select with care the areas to be read. Hand-held spot meters are popular with photographers who want exact measurement and control of individual areas. Some cameras with built-in meters have a spot metering option.

Meters built into cameras measure

reflected light. The lightsensitive part of the meter is a photoelectric cell. when the metering system is turned on and the lens of the camera is pointed at a subject, the cell measures the light reflected from that subject. With automatic exposure operation, you set either the aperture or the shutter speed and the camera adjusts the other to let in a given amount of light. Some cameras set both the aperture and the shutter speed based on the meter's viewfinder or data-panel readout.

Some noise can be

removed. Some DSLR cameras have a setting for long exposure noise reduction that works on the principle that some kinds of noise, notably dark noise, are predictable. long exposure followed automatically by an equally long exposure with the shutter speed.

Exposure changes are measured in

stops, a doubling or halfing of the exposure. A change in one aperture (f-stop) to the next larger aperture opening doubles the light reaching the sensor and results in one stop more exposure. A change in one shutter speed to the next slower shutter speed, also results in one stop more exposure. A change to the next smaller aperture or next faster shutter speed halves the light and produces one stop less exposure.

noise

the by-product of using a high ISO setting on your camera - it is often called grain

Exposure is a combination of

the intensity of light that reaches the light-sensitive surface (controlled by the size of the aperture) and the length of time the light strikes it (controlled by the shutter speed). You can adjust the exposure by changing the shutter speed, aperture, or both

In a digital photograph, the lower the light

the more noise. A sensor's photosites are less accurate when they measure a very small amount fo light, and in every photograph some will randomly generate pixels whose color and brightness are unrelated to the subject. Because noise increases as light level decreases, there will always be more in dark areas of an image. And because noise in shadows appears as bright sparkles of color in a dark field, it is most noticeable there

What happens when the lighting in a photo is not average

use bracketing

By placing main elements and subjects at the power points

we create a more balanced photograph and engage the viewer more. The photograph will be more aesthetically pleasing and easy on the eye.

Bracketing helps if

you are not sure about the exposure.