BASIC CAMERA TECHNIQUES. (An Overview)

Transcription

1 BASIC CAMERA TECHNIQUES (An Overview)

2 CONTENTS pg No. Digital Camera Basics - A primer 4 Pixels 4 Pixel Count Aspect Ratio White Balance Sensitivity Digital Zoom and Optical Zoom Setup mode 8 Focus modes 9 Auto Focus Prefocus Manual Focus Shooting modes 10 Automatic modes Semi-automatic modes Manual mode Metering modes 11 Centre-weighted metering Matrix (evaluative) metering Spot metering Scene modes 12 Backlight Beach/Snow Fireworks Landscape Macro Night Portrait Night Scene Party Portrait Landscape mode 13 ISO (Sensor Sensitivity) 13 2

3 Flash modes 14 Movie mode 14 Burst mode 15 File formats 16 JPEG file format Image quality 17 Shutter speed 18 Aperture 19 Exposure compensation 20 Exposure bracketing 21 Back-lighting Front-lighting Flash compensation 23 White balance 24 The Histogram 25 Focus and exposure lock 25 Framing shots with a LCD 26 How to hold your camera Reduce red-eye 27 Shutter-release button 27 Using a digital camera shutter-release button Controlling focus and exposure Confirming focus and exposure lock Shutter lag 28 Principles of composition 29 3

4 Digital Camera Basics - A primer Digital cameras are confusing to a lot of new users. In this basic guide to digital camera technology I hope to try to give digital beginners at least some basis to use in deciding which digital camera is appropriate for them. When shopping for a digital camera it's at least good to know what the basic terms like white balance, pixel, ppi and dpi mean and how they affect image and print quality. It's also important to know the difference between things like optical zoom and digital zoom as well as the advantages and disadvantages between storage formats such as Compact Flash (CF), Microdrives, Sony Memory Stick, Secure Digital (SD), Multimedia and camera interface technologies such as USB 1.1, USB 2.0 and Firewire IEEE Pixels A pixel is a contraction if the term PIcture ELement. Digital images are made up of small squares, just like a tile mosaic on your kitchen or bathroom wall. Though a digital photograph looks smooth and continuous just like a regular photograph, it's actually composed of millions of tiny squares as shown below. On the left the full image, on the right the area in the red square magnified to show individual pixels Each pixel in the image has a numerical value of between 0 and 255 and is made up of three colour channels. So for example a pixel could be 37-4

5 red, 76-green and 125-blue and it would then look like this. If it was 162-red, 27-green and 12-blue, it would look like this. There are over 16 million possible combinations using this scheme and each one represents a different colour. Computer savvy readers will note that each colour in this scheme can be represented by an 8-bit number (byte), so the colour of each pixel is defined by three colour bytes. This scheme can be expanded, for example to use 16-bits (two 8-bit bytes) for each colour. Images using three 8-bit values are sometimes called 24-bit colour images. Images using three 12-bit values for colour definition are called 36-bit colour images, and those using three 16-bit values are called 48-bit colour images. Pixel Count One of the main ways that manufacturers categorize their digital cameras is in terms of pixel count. What this is is the number of individual pixels that go into making each image. Today this number varies between 1 million (1 Megapixel) to around 14 million (14 Megapixels). A million pixels is abbreviated to MP, so a 1MP camera has 1 million pixels and a 3MP camera has 3 million pixels. Currently most popular consumer digital cameras have between 5MP and 7MP. A 3MP camera can make excellent 4"x6" prints and very good 5"x7" prints. If you intend to make lots of 8"x10" prints, then perhaps a 4MP or 5MP camera would be a better choice. Sometimes two numbers are given, total pixels and effective pixels. Total pixels count every pixel on the sensor surface. Usually the very edge pixels aren't used in the final image. Effective pixels are the number of pixels actually used in the image after the edge pixels have been dropped. 3MP 4MP 5MP Largest Image (typical) 2048 x x x 1944 Print size at 320dpi 6.5" x 4.8" 7.1" x 5.4" 8.1" x 6.1" Print size at 240dpi 8.5" x 6.4" 9.5" x 7.1" 10.8" x 8.1" Typical maximum image size vs. nominal Pixel Count. 5

6 Aspect Ratio The aspect ratio of a camera is the ratio of the length of the sides of the images. For example, a traditional 35mm film frame is approximately 36mm wide and 24mm HIGH. This has an aspect ratio of 36:24, which can equally well be expressed as 3:2. Some digicams use the same aspect ratio for their digital images. For example most digital SLR (single lens reflex) cameras have a 3:2 aspect ratio. However, video monitors typically use a 4:3 aspect ratio. For example a monitor with a 800x600 display has a 4:3 aspect ratio. With this in mind, most consumer level digicams use 4:3 aspect ratio for their images. White Balance With film you can buy "daylight balanced film" for shooting outdoors or "tungsten balanced film" for shooting indoors under normal domestic lighting (not fluorescents!). If you use daylight film under tungsten light the images will be very yellow. If you use tungsten film in daylight the images will be very blue. With film you have to correct for the "colour temperature" of the light using filters or by the right choice of film. With digital you can pick your white balance to suit your light source, so that white looks white, not yellow or blue. Normally there is an automatic setting and the camera decides what white balance setting to use. However if you know what your light source is you can usually set the camera to it and this may give better results. Most digital cameras have settings for sunlight, shade, electronic flash, fluorescent lighting and tungsten lighting. Some have a manual or custom setting where you point the camera at a white card and let the camera figure out what setting to use to make it white. Sensitivity Sensitivity settings on digital cameras are the equivalent of ISO ratings on film. Just about every digital camera will have settings with a sensitivity equivalent to ISO 100 film and ISO 200 film. Many will have an ISO 400 setting, but above that the images from cameras with small sensors gets pretty noisy. The more expensive digital SLRs with much larger sensors have much higher sensitivity settings. At ISO 400 they are virtually noise 6

7 free and some can go as high as ISO 3200 or even ISO 6400! Very few cameras have ISO setting lower than ISO 100 because noise levels are so low at ISO 100 there would be no real advantage in a slower setting. Quite a few digital cameras have an "auto" ISO setting, where the camera will pick from ISO 100, ISO 200 and sometimes ISO 400, depending on the light level and the mode in which the camera is operating. Digital Zoom and Optical Zoom Most cameras have both optical zoom and digital zoom. Optical zoom works just like a zoom lens on a film camera. The lens changes focal length and magnification as it is zoomed. Image quality stays high throughout the zoom range. Digital zoom simply crops the image to a smaller size, then enlarges the cropped portion to fill the frame again. Digital zoom results in a significant loss of quality as is clear from the examples below. It's pretty much a last resort, and if you don't have it in camera, you can do a similar job using almost any image editing program. Comparison of optical zoom and digital zoom 7

8 Setup mode The factory default settings for digital cameras can be changed via the Setup Mode. Here are some the most basic and common settings: Compression/Quality - Sets the compression for recording images typically Fine (best image quality for the file size selected), Normal (very suitable image quality) and Basic (least quality though images may be perfectly suitable for or posting on a web page. Compression settings may have other designations such as Best, Better, Good; Standard, High, Super High (See also, digital camera file formats). File size - Sets the number of pixels recorded for images. Frame number - Select the file name sequence for images. With Continuous setting, images are stored beginning with the highest file number used of the previous memory card. It prevents duplicate file names when images are transferred. Erase/Protect - delete individual photos from the memory card; protect images that you don't want to be removed during the erasure process Format - deletes all images from a card, even protected ones. Format occasionally for better card performance. It's best to format the card in the camera, not via the computer. Sounds - set the volume of the beep heard during camera operations. Select OFF if you wish to hear no sound. Date/Time - set date and time. Monitor - select LCD display options such as brightness and contrast. Power save - To conserve battery power, choose the length of time before the LCD automatically goes off or the camera goes into standby mode. Other - select a focus mode, set the self-timer, turn the digital zoom on and off. 8

9 Focus modes Most consumer digital cameras often have more than one focusing mode. When using an automatic mode, focus is locked when the shutter-release button is pressed half-way down. Correct use of the two-step shutter button is key to obtaining proper focus. The LCD or electronic viewfinder indicates when, and sometimes where, focus is locked. There is a visual indicator, such as a small lamp or change in colour of the focus indicator, that confirms when focus is achieved. Auto Focus Single (or one) area focus - camera focuses on a subject in the central area of the screen. Focus adjusts according to the distance of the subject. This is the most common focus mode. Continuous autofocus - focuses continually on a subject; useful when shooting slow moving subjects. However, if your photos are often poorly focused switch to single area focus. Continuous autofocus consumes more battery power. Spot focus - camera focuses on a very precise centre area of the screen. 3, 9-area focus - camera automatically focuses using one or more focus points. The focus positions change according to each subject, focusing on a number of objects within a scene. Face-Priority AF - In 2005, Nikon introduced Face-Priority autofocus, which is activated when select CoolPix digital cameras are switched to Portrait mode. A special digital detection program scans for facial details and then controls autofocus operation based on the location of the detected face in the scene. Even if the subject moves, or as the photographer recomposes the picture, Facepriority AF keeps focus on a subject's face. Pre-focus Pre-focusing can be effectively used when there is a pre-determined, similar distance between the camera and subject. Focus is fixed until you press the focus button again or switch to a different focus mode. Digital cameras have different methods of prefocusing, so check the manual. Manual Focus Manual Focus Area- focus on a portion of a scene when not centred in the frame. Use one of several focus area indicators. Select the area by toggling a cursor button. This method is useful for close-up and macro shots. Focus ring - focus manually, from a few feet to infinity, by turning a focus ring near the lens. 9

10 Focus button - depress a manual focus button and rotate a dial until the subject is in focus. Shooting modes All digital cameras have fully automatic modes to take photos by simply pointing and shooting. Intermediate and advanced cameras that have semi-automatic and manual modes allow for more creative and technical control. Automatic modes Auto/Simple - fully automatic, point-and-shoot mode, which lets beginners easily take photos. The camera selects all settings. Program AE - camera automatically sets the shutter speed and aperture based on the brightness of the scene. User can adjust some settings such as exposure compensation, white balance, ISO, focusing and metering modes. Semi-automatic modes Shutter priority (Tv) - User selects shutter speed and the camera automatically selects the aperture. Selecting a faster shutter speed allows you to "freeze" the action of a moving subject. Slower shutter speeds capture movement and also let you shoot without a flash in dim lit scenes. Aperture priority (Av) - User selects aperture and the camera automatically selects shutter speed. Opening up the aperture (smaller f-stop number) decreases depth of field. Closing down the aperture (higher f-stop number) increases depth of field. Manual mode User manually selects the shutter speed and aperture. An Exposure Display visible on the LCD or electronic viewfinder shows the amount a photo will be over- or underexposed. Long exposures are taken in manual mode. 10

11 Metering modes Automatic exposure is a standard feature on all digital cameras. The metering system measures the amount of light in a frame and determines the best exposure. Many cameras have more than one metering mode and each evaluates a scene in a different way. Centre-weighted metering Currently the most common digital camera metering system. Centre-weighted is the metering system of choice on digicams that do not offer other metering modes. Exposure metering is averaged over the entire frame with emphasis placed on the central area. Used for general and portrait photography. Matrix (evaluative) metering A complex metering system whereby a scene is split up into a series of zones. Overall exposure is based on evaluating each zone individually and taking an average of the total light readings. Spot metering Takes a precise exposure reading only at the very centre of the frame and disregards the rest. A spot meter is used when a subject is backlit or has bright light upon it and the background is dark, ie. when there are extremes in brightness in a scene. Also useful for macro photography. 11

12 Scene Modes Digital cameras offer a variety of useful modes, which are optimized for specific scenes and photographic conditions. Scene modes are preprogrammed by the manufacturer to automatically give the best exposure and settings for each scene. When selected, a scene mode can often give better results than shooting in fully automatic mode. Common digital camera scene modes: Backlight - eliminates dark shadows when light is coming from behind a subject, or when the subject is in the shade. The built-in flash automatically fires to "fill in" the shadows. Beach/Snow - photograph beach, snow and sunlit water scenes. Exposure and white balance are set to help prevent the scene from becoming washed out looking. Fireworks - shutter speed and exposure are set for shooting fireworks; pre-focusing & use of tripod recommended. Landscape - take photos of wide scenes. Camera automatically focuses on a distant object. Macro - take close-up shots of small objects, flowers and insects. Lens can be moved closer to the subject than in other modes. Hold the camera steady or use a tripod. Night Portrait - take photos of a subject against a night scene. The built-in flash and red-eye reduction are enabled; shutter-speeds are low. Use of tripod recommended. Night Scene - photograph nightscapes. Preprogrammed to use slow shutter speeds. Use of tripod recommended. Party - take photos in a dim lit room; exposure and shutter speed are automatically adjusted for room brightness. Captures indoor background lighting or candlelight. Hold the camera very steady when using this mode. Portrait - main subject is clearly focused and the background is out of focus (has less depth of field). Best when taking shots outside during the day. Shoot using a mid to long telephoto lens, stand close to your subject within the recommended camera range and, when possible, select an uncomplicated background that is far from the subject. 12

13 Landscape mode Many digital cameras have a Landscape Mode, which is a long distance scene mode also known as Infinity mode. Landscape mode is represented by an icon that looks like a mountain range. Landscape mode provides maximum sharpness for distant and wide-vista scenes. It is suitable for photographing cityscapes, seascapes, skyscapes and forests. When switching to landscape mode, the focus is fixed at infinity. There is usually no need to check focus before taking a picture. However, if there are objects in a scene, lock focus on one that is about third of the way between the nearest and furthest object. Infinity mode can be useful when photographing through glass, chain-link fences and other similar scenes that are difficult to determine just where to focus. Landscape mode shutter speed & aperture The digital camera may automatically choose a small lens aperture. This is to provide a deep depth of field. A slow shutter speed may also be selected by the camera when using landscape mode. If light is low, hold the camera steady or use a camera support such as a tripod. ISO (Sensor Sensitivity) Auto ISO mode All consumer digital cameras have an Auto ISO mode. The camera automatically selects the sensitivity, known as ISO, according to the level of light in a scene. The user has no control over which ISO number is used. In bright light a lower ISO will be selected. In low light an higher ISO number will be selected. Auto High ISO Mode Some digital cameras have an Auto High ISO mode, which is primarily used in very low and difficult lighting. The camera selects ISO number higher than Auto ISO mode, usually ISO 400 and above. Higher ISO means faster shutter speeds When a higher ISO is selected, shutter speeds are faster. Use of faster shutter speeds helps prevent blurred images due to camera shake. Using high ISO numbers also allows you to turn off the flash when shooting in dark areas. 13

14 Higher ISO means more image "noise" Keep in mind that the higher ISO, the more noise will appear in images. That's why many photographers, in order to prevent noise, prefer to set ISO manually and select low ISO numbers even if they must use a tripod to prevent camera shake. Still, a photo with noise is better than no photo at all, maybe? Image noise will be higher when using Auto High ISO mode. Flash modes Many digital cameras have several flash modes to choose from. A built-in flash is small and not very powerful so whichever mode you use, make sure to stay within the specified flash range. Digital camera flash modes Automatic mode - flash triggers automatically. Turn this mode off when in places that forbid inside flash photography, such as museums and theatres. Red-eye reduction - fires the flash several times just prior to exposing a photo. Reduces the reflection in a subject's eyes which produces red eyes. The rapid flashes cause a subject's pupils to contract and helps minimize the redeye effect. Forced (fill-in) flash - keeps the flash on in situations where automatic mode would keep it off. Used when additional illumination is needed such as when the main source of light is in the back of a subject or shadows prevent details from showing. Suppressed flash - turns the flash off Slow sync (also called Night Scene)* - use to capture a dimly lit background at night. The flash fires briefly to light the foreground subject. Rear-curtain sync* - Similar to slow synch but flash doesn't fire until right before the shutter closes. Flash exposure compensation - used to increase or decrease the output of the flash. *Tripod or other camera support recommended Movie mode Many digital cameras record movies. The quality ranges from mediocre to outstanding. Digital cameras such as the Canon S series are capable of recording video that approaches the quality of a dedicated camcorder. In the past, digital cameras only recorded short videos of seconds, some without sound. That has changed since many users now expect their digital cameras to have video capability. 14

15 If you plan to shoot a lot of video with a digital camera, check before buying if it has a limited recording time. There are cameras that have no limit at all and record until the memory card is full. A high speed memory card may be required to obtain the best performance when shooting at the highest video resolution and fastest frame rate. Video files are huge so if you plan to do a lot of recording buy one or more large capacity memory cards. Video output mode setting Make sure your camera is set to the record video output to the standard for your country. If you live in the U.S.A., Canada or Japan, set your video to NTSC. Select PAL if you live in a European country or in China. Burst mode Many digital cameras have a burst mode to take a series of shots in rapid succession. While the shutter button is fully pressed down, the camera shoots continuously. Images are held in the camera's buffer then saved to a memory card or the camera's built-in memory. Burst mode is useful for taking photos of fast moving subjects where it is difficult to judge the correct timing to get a good photo. Because shots are taken sequentially, only the best of a series can be kept. When shooting a rapidly moving subject, pre-focusing is often necessary. Some digital cameras offer more than one continuous mode such as Continuous Low, Continuous High and Ultra High. The number of images and the speed at which they are recorded varies from one camera to another. Write speed can also vary according to the image resolution and compression settings selected. A camera make take only a predetermined number of photos in burst mode. For others, the actual number of images captured continuously is limited only by the capacity of the memory card or the size of the camera buffer. For best performance when shooting in high speed continuous mode, make sure batteries are fully charged. High speed performance is usually at it's best when using a high speed memory card. 15

16 File formats There are three types of digital camera file formats: JPEG TIFF RAW The most commonly used format, JPEG, is often the only one available on entry-level and some intermediate digicams. Not to worry, the format is perfectly fine for the vast majority of digital camera users, particularly when the camera is set at the highest JPEG quality setting. Many higher-end digital cameras let you select between JPEG, TIFF and RAW. Professional photographers and serious photo-enthusiasts usually prefer to shot RAW. Some advanced cameras have a setting to simultaneously shoot RAW + JPEG. Both formats will be saved to a memory card as separate files JPEG file format JPEG, pronounced jay-peg, is an acronym that stands for the group that developed the file type, the Joint Photographic Expert Group. JPEG is a method of compression which significantly reduces the file size of photographic and other continuous tone images. An image in JPEG format has a.jpg extension: filename.jpg. Digital cameras offer several JPEG compression levels and quality settings. For images with the least compression, the loss of quality is usually not seen by the human eye. Keeping jpeg compression to a minimum is a must if you want to print quality photos. Some digital cameras only offer the jpeg file format. Advanced digital and Single Lens reflex cameras offer the option of shooting two additional file formats, TIFF and RAW. JPEG files, unlike TIFF and RAW files, do not take up as much room on a memory card. They are also processed faster by the camera than the other file formats. JPEGs store important camera settings and scene information known as EXIF data. 16

17 Image quality Image quality and file compression Digital cameras store images in a compressed format called JPEG. JPEG is the most commonly used file format. Some cameras also have uncompressed formats (TIFF and RAW). When images are compressed their file size becomes smaller so more can be saved to a memory card. However, if compression is set too high, image quality is reduced. For optimal image quality, select the least compression and highest resolution (highest number of megapixels). Digital cameras provide a variety of compression levels: Super Fine, Fine, Normal and Basic (terms vary among manufacturers). The Fine setting produces the least compression and best image quality. If you intend to print and crop images, use the least compression. If you only plan to post images on the web, or send via , using a higher compression is okay. But keep in mind that you may wish to print a photo, so using the least compression is still the best setting when taking photos. Image size/resolution The size, or resolution, of an image can be changed in a digital camera. Resolution relates to the size an image appears on a computer monitor, not the physical dimensions an image prints. For example, sizes on a four megapixel digital cameras can be: 2272x1704, 1600x 200, 1024x768 and 640x480 pixels. You may mix compression and image sizes on memory cards. 17

18 Shutter speed Shutter speed is the amount of time the shutter remains open to allow light to reach a digital camera sensor. Shutter speed is measured in seconds, or fractions of seconds. Using very fast shutter speeds "freeze" fast-moving subjects, such as birds in flight. Slow shutter speeds are used to intentionally capture the movement of a subject. How an image is exposed is determined by the combination of the lens aperture and shutter speed. A fast shutter speed will use a larger aperture (small F-stop number) to avoid an under-exposed image. A slow shutter speed requires a small aperture (large F-stop number) to avoid over-exposure. Typical shutter speeds are: 1/2000 second, 1/2000 sec, 1/500 sec, 1/250 sec, 1/125 sec, 1/60 sec, 1/30 sec, 1/15 sec, 1/8 sec, 1/4 sec, 1/2 sec and 1 second. On some digital cameras you can manually set shutter speed a lot slower than a second for very long exposures. Use a tripod when taking long exposures to prevent camera shake. For most, hand holding a digital camera at shutter speeds below 1/60th of a second often requires use of a camera support. Shutter Priority Mode Shutter Priority mode is a semi-automatic exposure mode. You select the shutter speed and the camera automatically sets the aperture for a proper exposure. For digital cameras without Shutter Priority, use Sports, Kids and Pets or Fast Shutter mode. 18

19 Aperture The aperture controls the amount of light that reaches a digital cameras sensor. An aperture acts much like the pupil of an eye that opens wider as light decreases to let in more available light. The pupil gets smaller when light increases to reduce the amount of light entering the eye. The combination of aperture and shutter speed are related, and effect the exposure value. The faster the shutter speed, the larger the opening of the lens and visa versa. F-stops The diameter of an aperture is measured in f-stops. A lower f-stop number opens the aperture and admits more light onto the camera sensor. Higher f-stop numbers make the camera's aperture smaller so less light hits the sensor. When an aperture is opened up by one f- stop, the amount of light which reaches the sensor is doubled. F-stops are expressed in three different ways: f/8, f-8, and 1:8. Aperture settings can be used creatively to control depth of field, how much of a photo is sharp in front and back of where you focus on the main subject. The technique is useful for close-up and portrait shots. Aperture Priority Mode All digital cameras have exposure modes that automatically control the aperture and shutter speed. But many allow you to manually change the aperture. When using aperture priority mode, you change the aperture and the shutter speed is automatically changed to maintain proper exposure. 19

20 Exposure compensation Exposure Compensation is an important tool that helps you control the amount of light entering the lens. The human eye is capable of seeing detail in both dark and light areas of a scene. However, digital cameras have a more limited range. Under somelighting conditions a photo can be either under or over-exposed. In these situations, the Exposure Values can be changed to help improve the overall exposure. Exposure Values (EV) Selecting an acceptable Exposure Value helps preserve detail in both dark and bright areas of a photo. In high contrast scenes, photographers usually under expose so the brightest areas are not blown out (i.e. washed out and contain no detail). Dark areas generally retain detail better than bright areas. An under exposed image can usually be edited to pull out details in the darker portions of a photo. Exposure Values are numbers that refer to various combinations of lens aperture and shutter speed. The values are measured in "steps," typically between (+) 2 EV through (-) 2 EV in increments of 1/2 EV or 1/3 EV. Decrease the EV if photos appear too light (over-exposed). Increase the value if photos are too dark (under-exposed). Exposure Compensation Exposure Compensation can be changed manually using a digital camera's exposure compensation button or menu. This lets you to override the metered exposure by a value between a range of [-] 2 to [+] 2 EV. How settings are adjusted varies according to a scene or the subject matter itself. The best way to learn about exposure compensation is to experiment. 20

21 Exposure bracketing Photo enthusiasts and professionals have long relied on a technique known as exposure bracketing. Bracketing helps ensure correct exposure of a photo when lighting in a scene is difficult. Extremes in light can trick a camera meter to improperly exposing a photo. Bracketing overrides the exposure settings. Bracketing can be set manually on some cameras. More often that not digital cameras can be set to bracket automatically. When auto exposure bracketing is enabled, the camera takes two to five consecutive pictures of the same scene. The Exposure Values automatically change in plus and minus incremental steps. Back-lighting The first three shots were taken with the source of light coming from behind the subject. This is known as back-lighting. Without changing the Exposure Value from the default exposure reading, back-lighting causes the main subject to be under exposed, ie. dark. 21

22 Front-lighting The next three shots were taken when the main source of light fell on the front of the subject. The strongest light came from behind the person taking the picture. Without adjusting the Exposure Value when light falls too strong on a subject, the image becomes overexposed. What results is an photo with washed out, blown out areas. Better to under than overexpose It is generally better to under- rather than overexpose an photo. When editing, it is often possible to pull out detail from the darker, underexposed areas. When portions of an image are washed out due to overexposure, there remains little or no detail to pull out in the blown-out area. In difficult lighting situations, he use of exposure bracketing usually saves the day. 22

23 Flash compensation Flash compensation is an feature found on some digital cameras that allows the user to increase or decrease the flash power. This is done by manually changing a camera setting. Flash compensation differs from exposure compensation in that it only changes the flash output and not exposure, aperture or shutter speed. Flash compensation should be used when the automatic flash causes underexposure (too dark) or overexposure (too washed out) of a subject. +1 Flash Compensation 0 Flash Compensation -1 Flash Compensation 23

24 -2 Flash Compensation White balance The colour of light reflected off a subject changes with the colour of the main light source. The white balance setting on a digital camera adjusts the brightest part of a scene so it appears white. The human eye sees white objects as white regardless of the light source; a digital camera does not. Digital cameras are set to automatic white balance by default. Automatic white balance does a very good job under most circumstances. However, there are times when white balance needs to be changed manually to match the inside or outside lighting in order to obtain more true-to-life colours in a photo. Preset white balance settings: Daylight - for direct sunlight Cloudy - for shady, overcast skies Fluorescent - for use under fluorescent lighting Incandescent/tungsten - for use under standard light bulbs and some types of fluorescent lighting Flash - for light produced by the built-in camera flash Photos of a white door were taken under the same lighting conditions (standard light bulbs). Automatic white balance was used to shoot the image on the left image. Incandescent white balance setting was use for the image on the right. 24

25 The Histogram Many digital cameras have a histogram that is viewed on the LCD or electronic viewfinder. The histogram provides an indication of whether or not an image is properly exposed so that you don't lose detail in the shadows and highlight area. If the histogram indicates that an image is not exposed properly, change exposure settings and retake the picture. Focus and exposure lock When the shutter-release button is pressed half-way down, focus and exposure are locked. Where you point the camera is important. This photo is poorly exposed. The cameras exposure meter was fooled by the bright sky and underexposed the picture, making important areas appear too dark. This photo is exposed more correctly. The photographer consciously locked focus on a mid-toned area of the house, indicated by the red dot, then recomposed before fully pressing the shutter-release button. A mid-toned area was selected to obtain an acceptable exposure balance that would capture detail and colour for the home. In difficult lighting conditions, obtaining proper exposure often involves compromise. The goal is to find the best exposure for the most important areas of a scene. 25

26 When using this technique, watch for changes in exposure on the LCD as you preview the scene. Don't press the shutter button halfway down until exposure looks just about right. To obtain similar results, bracket or use exposure compensation. Framing shots with a LCD Framing a shot with the LCD is relatively worry-free when lighting conditions are ideal and shutter speeds are fast. However a digital camera is more prone to camera shake using a LCD instead of a viewfinder, especially if your camera doesn't have image stabilization. Camera shake causes images to blur. It primarily occurs when taking photos handheld at shutter speeds under 1/60th of a second. It also may occur when using a telephoto lens. Even if lighting is adequate and shutter speed is fast, it's good practice to hold the camera steady. How to hold your camera Because a digital camera is held away from your body when composing shots with a LCD, hold it with both hands. The camera can be steadied with the left hand and the right hand used for further support and to press the shutter-release button. Keep the camera as close to your face as possible. Brace your elbows against your body for additional support. You can get additional support when needed by steadying yourself against a wall, table, car top or anything with a flat, level surface. When a digital camera is held vertically, take extra care that your fingers don't cover the built-in flash. If you inadvertently cover part of the lens, you will see that on the LCD so you can remove your fingers before taking a photo. Reduce red-eye 26

27 Red-eye is caused by light from a flash hitting the eyes and the light is reflected back into the lens. Red-eye is a frequent problem when using a built-in digital camera flash because of it's proximity to the lens. Digital cameras have a red-eye flash mode that fires a series of pre-flashes prior to the final flash. The rapid flashes cause pupils to contract and reduce the reflection. Though not perfect, red-eye flash mode can help minimize, sometimes prevent, the red-eye effect. When using this mode, inform your subjects since the pre-flashes may startle them and cause weird expressions on their faces. Reducing red-eye When using a built-in flash, have the subject look toward the camera but not directly at the lens. Don't rely solely on the flash for illumination. Use other light sources such as light coming through a window or door. If you turn on room lights, make sure to adjust the white balance setting. Some digital cameras remove red-eye in the camera, however it is not always as effective as using software. The most effective way to prevent red-eye is to use an external flash. Shutter-release button Using a digital camera shutter-release button Using the shutter-release button on a digital camera is quite different than using one on a film camera. The difference is vital to understand. If you don't press the button in the right sequence, photos will be improperly exposed and focused. Pressing the shutter-release button down correctly helps prevent camera shake. Even the slightest movement during the record time of a shot can result in blurred images. With a film camera, the shutter-release button is pressed down in a single step. However, it's a two step process when using a digital camera. When the shutterrelease button is depressed half-way, exposure and focus are locked as long as you hold it in that position. Controlling focus and exposure Use the first stage of pressing the shutter-release button to gain more control over where the camera actually focuses and exposes. Once locked, take the photo. When focus and exposure are achieved, keep holding the button down halfway if you must recompose. Some digital cameras let you lock focus and exposure separately. Confirming focus and exposure lock 27

28 An indicator on the LCD, electronic viewfinder or a light on the camera near an optical viewfinder glows steadily to confirm the lock. Once the camera confirms focus and exposure, then fully depress the shutter button to take the shot. This two-step process is such a critical digital camera technique that you must take time to learn it. All digital camera manuals contain instructions about the technique. Check them out, then practice until you get the rhythm of the sequence and using it becomes second nature. Shutter lag Shutter lag is the amount of time (delay) it takes from when you fully depress the shutter-release button to the moment the picture is taken. Shutter lag times vary from digital camera to digital camera. Digital Single Lens Reflex cameras have little or no discernable shutter lag and the delay is getting shorter for many newer consumer digital cameras. If your digital camera has shutter lag, follow these suggestions to help decrease the lag time. Decreasing the effect of shutter lag: use the two-step shutter release button correctly - this point can not be emphasized enough use fully charged batteries anticipate the moment or track the action: use "continuous autofocus" mode, lock focus and then press the button fully down. prefocus - focus on an object that is at the same distance where the subject will come, lock focus and then wait for the subject to come into view 28

29 Principles of composition Centre of interest: a photograph should have a strong focal point. Determine what it is before composing your photo. Simplicity: keep your composition simple, avoiding busy background that distracts from a subject. Subject off centre: Place a subject slightly off-centre rather than in the middle of a photo. Horizon lines: Don't place the horizon line, or any strong vertical or horizontal lines, right in the middle of a picture. Make sure the lines aren't tilted! Leading lines: if a scene has strong lines, make sure the lines lead the eye into the frame rather than out of it. The lines should lead to the main point of interest. Foreground objects: Include an interesting object in the foreground of a scene. It adds depth, dimension and point of reference. Vary angles: Shoot at varying angles to capture a subject at a different viewpoint. Move the camera higher or lower than you usually do. For a dramatic effect, take some photos from a birds-eye (looking down) or wormseyes view (looking up). Framing: Framing a subject by zooming or moving closer draws attention to it. Using foreground objects in a scene can add depth and point of reference. Silhouettes: Subject made dark by photographing it against a light background (back lighting). Reflections: adds an interesting, sometimes abstract, look to a photo. Symmetry: an identical or near-identical image of its other half. Use of symmetry often provides a formal balance. 29