June 24, 2006
Batteries for Digital Cameras
Digital cameras are electronic devices so they need a power source of some kind. The most convenient way to power your camera is with batteries. Although some models can be connected directly to an AC outlet, this is impractical for anything but studio use.
Digital cameras are 'high drain' electronic devices which mean they require batteries which have a comparatively high energy level over their energy cycle. The best type of rechargeable batteries for digital cameras is NiMH (Nickel-Metal Hydride). These relatively inexpensive batteries will keep your camera operating longer than any other standard type of battery. NiMH batteries are made from non-toxic materials so they are environmentally friendly.
Some manufacturers supply lithium-ion batteries for their digital cameras. They are more expensive than NiMH batteries but hold their charge almost twice as long. They also don't lose their charge while in storage the way that NiMH batteries do, and their power drains at a predictable rate so that it is easy to gauge how much power is left.
Alkaline batteries are not suitable for digital cameras. You can always use them if nothing else is available, but their power will be used up after just a few shots. Rechargeable alkaline batteries are even worse -- they may only be good for two or three shots.
A set of fully charged NiMH batteries may give you up to 100 shots if you are careful with power consumption. This number will be reduced if you use the flash a lot, leave the monitor on between shots, and do a lot of zooming and focusing.
Battery Chargers
Battery chargers come in a variety of models – be sure to get one that is rated for the type of batteries you are using for your digital camera. Some chargers can handle both NiMH and NiCad batteries but if these chargers are not set up properly they can damage the batteries by overcharging them.
Some of the inexpensive battery chargers keep on charging the batteries for a fixed length of time. This can be bad for the batteries because they can be overcharged. Look for a battery charger that has a micro processor which controls the charging cycle. This type of charger switches off automatically when the batteries reach their maximum charge.
Posted by DigitalCamera at 10:51 AM | Comments (0)
June 23, 2006
Camera Tripods
Tripods are a necessity for anyone who wants to take the best pictures possible. They are useful for many different situations by helping to minimize camera movement which can cause an image to blur.
There are hundreds of tripods to choose from in a broad range of prices. The most expensive ones are made of composite materials such as carbon fiber which is lighter and more durable than either aluminum or alloy. Expensive tripods are usually equipped with quick release mechanisms for adjusting the legs and the camera mount.
Each tripod has three heights which must be considered -- maximum, minimum, and collapsed. For most purposes, the maximum height should allow you to use the camera at a comfortable standing position. You rarely need a tripod higher than this. If you do a lot of close-up work, the minimum height is an important measurement, although extensions can be added to the head which allow the camera to be brought close to the base of the tripod. Finally, the collapsed height is important to determine the tripod's portability -- compact tripods are usually easier to carry around.
Tripods usually have a center column to attach the tripod head. This center column can be used for fine height adjustment and some models allow the camera to be tilted down towards the ground for closeup work. Look for a center column with a hook – these can be used to hang heavy objects for increased stability.
Tripod heads are the part of the tripod that the camera attaches to. They allow the camera to swivel and move up and down. This movement is accomplished with two basic types of head – the three-way pan tilt head, and the ball head.
Traditional heads are the three-way pan tilt type. They have three different axes and each is controlled with its own mechanism and lock. The locking mechanisms make this type of head ideal for situations where precise control of the visual field is needed, but can be inconvenient for other uses.
Ball heads allow all three axes to be set at the same time, so they are easier to use. They are also more expensive but most photographers gladly accept the higher price for the increased flexibility in camera movement.
Monopods are an ideal alternative to tripods where portability is a concern. They consist of a single support which the camera is mounted on. Outdoor photographers often prefer monopods over tripods because the latter are bulky and difficult to set up.
Using a monopod is almost as easy as pointing and shooting. The monopod gives the camera the extra stability necessary for good quality shots.
Carrying a tripod is easier with a case or a carrying strap. Cases can be used to hold all your camera equipment but are bulky to carry around. If you don't have a lot of equipment a shoulder strap is the best solution for carrying the tripod. If the camera needs to be perfectly level, small bubble levels can be attached to the tripod. Some tripods come equipped with levels, but they are also available as inexpensive accessories.
Posted by DigitalCamera at 10:56 AM | Comments (0)
June 22, 2006
Lenses for Digital Cameras
There are two major components of digital cameras that play a big part in image quality – the image sensor and the lens. Get the best you can afford -- good quality lenses are essential for getting the most out of digital photography.
Long lenses are sometimes called telephoto lenses. Because of their reduced field of view, the images shot with telephoto lenses are magnified compared with shorter lenses. Similarly, shorter lenses give a wider field of view, so very short lenses are called wide-angle lenses.
A 'normal' lens is one that produces an image similar to what the human eye sees. There is no standard length for a normal lens because field of view is directly connected with the size of the image sensor that captures the photo. A 50mm lens is considered normal for traditional 35mm cameras but digital image sensors are much smaller than a frame of 35mm film, so shorter lenses on digital cameras will capture the same field of view as the 50mm lens on a 35mm camera. The specifications of a digital camera lens will often include a reference to how the focal length compares to a 35mm camera.
Almost every digital camera has an optical zoom function that changes the focal length of the lens. They are rated as a multiplier – a 3X zoom will enlarge or reduce an image by 3 times from the longest to the shortest setting.
Some cameras are also equipped with a digital zoom. These work by cropping the image digitally and then spreading the result over all the photosites on the image sensor. This is inferior to optical zoom and should not be used. Better results can be obtained by editing the photo using computer software.
Most digital cameras in the mid-range and better have the ability to add lens converters. These give you more options for digital photography by allowing you to attach various types of lenses and filters.
In addition, many digital cameras can accept lenses made for film cameras. Because of the difference in size between film and image sensors, however, these lenses do not produce the same results as with film cameras. A telephoto lens designed for film will have a larger magnifying effect, and a wide angle lens will have less effect on a digital camera.
Lenses are quite expensive. They should be kept in cases and covered with caps when not in use. Most lenses come with caps but you may have to buy extras in case they are lost. They are widely available and fairly inexpensive.
Lens hoods are useful for controlling the amount of light entering the lens. They result in images that have less contrast – useful for some outdoor situations.
Posted by DigitalCamera at 12:59 AM | Comments (0)
June 21, 2006
Classic Photography vs Digital Photography
Even though digital photography is a revolutionary new way to take pictures, it is very much based on traditional photography and uses many of the same principals. Both types of photography require a lens to focus the light and a shutter to allow the light to enter the camera. The main difference between digital and traditional photography is how the image is captured.
The quality of a digital photograph depends a lot on how many pixels it has. The number of pixels is sometimes referred to as the 'resolution' of an image, and can be expressed as a dimension (800 x 600), or the number of pixels per inch. A common resolution for computer screens is 800 x 600 and this means the monitor can display 800 pixels from side to side and 600 pixels from top to bottom for a total of 480,000. Digital photography commonly uses much higher resolutions than computer screens with resolutions in the millions of pixels (megapixels). A camera with a resolution of 2048 x 1536 has a total resolution of 3.1 megapixels.
As mentioned above, each pixel is represented by a number. The size of that number determines the colours scale that can be represented. For example, black-and-white pictures can be represented with pixels which are just eight bits in length. If you are familiar with binary arithmetic, you know that an 8-bit number can represent decimal numbers from 0 to 256. Black-and-white photographs, therefore, can have a total of 255 shades of gray as well as black (0) and white (256).
Colour must be represented with larger numbers. 16 bits per pixel, for example, is necessary to have a colour scale of 65,536 different shades. 24 bits per pixel can represent more than 16 million different colours. Most digital cameras use 24 bits per pixel, but some professional equipment has a colour resolution of up to 48 bits per pixel for more than 280 billion different shades.
There are several factors that affect the quality of a digital camera, but pixel resolution is usually seen as the most important. Choosing an adequate pixel resolution depends a lot on the size of the photographs you want to print. Keep in mind that the number of pixels in an image does not change, so pictures with larger dimensions will have fewer pixels per inch which results in a loss of detail if the picture size becomes too big.
Of course, there is nothing to stop you from printing larger pictures. Pictures printed at 200 pixels per inch are slightly less sharp but still quite acceptable for many purposes. At this resolution, you can get pictures up to 8.7" x 5.8" from a two megapixel camera, and 12.2" x 8.2" from a four megapixel camera.
Posted by DigitalCamera at 11:35 AM | Comments (0)
June 20, 2006
Digital Camera Buying Guide – Part Two
The simplest digital cameras are point-and-shoot cameras -- simply aim them and push the button. They are very easy to use and are suitable for people who simply want to take family or vacation snapshots. The downside to point-and-shoot cameras is the lack of control you have over focusing and image adjustment. As you go up the scale to more expensive cameras, you get more of these kinds of options. The simplest point-and-shoot cameras often have a low megapixel rating -- around two megapixels.
You are presented with many choices when buying a digital camera. There are different types of image sensors, storage cards, batteries, as well as extra features like video and audio recording. As mentioned in the previous article, image sensors and lenses are the most important parts of a digital camera for capturing quality images. They are not the only things to consider, though.
Controls
Many of the controls on digital cameras are accessed through a menu system. An easy-to-use menu system is a great benefit to any digital photographer, so this is an important point to consider when shopping around. The menu system should be clearly laid out so that you can access settings such as resolution, flash, and exposure settings. Too many buttons can be confusing and can inhibit the average user from accessing all the features.
Exposure Settings
Exposure settings allow you to adjust the camera for various types of light. Almost all digital cameras have an automatic mode which will do the adjusting for you, but better cameras will give you more control over aperture settings and exposure times. These can give your photos a more professional look, but some people may not be interested in this level of control.
Video and Audio
Many digital cameras allow you to shoot videos and/or record sound. These features can be handy, but the amount of video that can be captured is quite small compared to a dedicated camcorder.
LCD Display
LCD displays allow you to see pictures you have taken. This is essential for deciding which shots to keep and which to discard. The display may also function as a viewfinder allowing you to see how your shot will look before you press the shutter button. Some of the cheapest digital cameras do not have an LCD display.
Software
Try Before You Buy
If possible, take a few pictures with a digital camera before you buy it. This will give you a feel for the controls and the ease of use. How does the camera feel? Is it solid or does it seem like a plastic toy? Is the LCD screen easy to view under various lighting conditions? Giving the camera a tryout will answer these questions.
Posted by DigitalCamera at 12:11 PM | Comments (0)
Digital Camera Buying Guide – Part One
Are you ready to take the plunge into the world of digital photography? This series of articles will help you choose the best camera for your needs.
Resolution
Digital cameras are rated by the number of megapixels (millions of pixels) they can record. This is also referred to as their 'resolution' and is the single most important factor affecting the price of digital cameras. Quite simply, the more megapixels the higher the price.
Images which are only viewed on a computer screen did not need a high resolution. A computer monitor set to 1280x1024 (which is very large) is only displaying about 1.3 megapixels. Any digital camera rated at about two megapixels is suitable for computer images.
Printed pictures, however, are another story. Professional photo shops usually print photographs at 300 dots per inch, and you are likely to be disappointed with pictures printed at less than this standard. A 4 x 6 photograph printed at 300 dots per inch needs an image which has about 2.8 million pixels. That means that digital cameras that are meant to be used for printed pictures should be rated at least three megapixels.
More megapixels doesn't necessarily mean better pictures. All other things being equal (image sensor quality and lens quality) a camera with more megapixels simply allows you to print larger pictures. You also have more options for cropping photos and maintaining standard print sizes.
Budget
Now that you have chosen a minimum megapixel rating, you can look for cameras which fall into your budget. You will most likely want to get the best quality images for your money, and that may mean foregoing some of the fancy features such as video and sound recording. Concentrate on lens quality and image sensor quality.
Lenses are available in either plastic or glass. Glass lenses are superior and will produce crisper, cleaner images. The best cameras will be equipped with lenses by well-known manufacturers such as Leica or Zeiss.
Image sensors are electronic devices that record the images. The two most popular types are CMOS (Complementary Metal Oxide Semiconductor) and CCD (Charged-Couple Device). CMOS is the cheaper of the two but the image quality is inferior to CCD.
No matter what your budget, a camera with a good quality lens and CCD image sensor will likely give you pleasing digital photographs.
Posted by DigitalCamera at 12:09 PM | Comments (0)
June 19, 2006
How a Digital Camera Works
Digital cameras are quite similar to traditional cameras in their operation. They both have a lens to focus the image, a shutter to allow light inside the camera, and an aperture to control the amount of light which enters the camera.
Image sensors are electronic devices made up of an array of electrodes (or photosites) which measure light intensity. The most common type of image sensor for digital cameras is the CCD (Charge-Coupled Device) although others such as CMOS and Foveon are sometimes used.
The number of photosites in the image sensor gives the digital camera its megapixel (millions of pixels) rating. Each photosite corresponds to a pixel in the final image, so a camera which is rated at six megapixels, for example, has an image sensor which is 3008 pixels wide by 2000 pixels high.
When light hits the image sensor it is converted into electrical signals which are amplified and fed to an analog-to-digital (A/D) converter. The A/D converter changes the electrical signal into binary numbers which are processed by a computer housed in the camera body. Once the numbers have been processed the resulting image is stored on a memory card.
Photosites can only measure intensity of light -- not colour. In order to produce a colour image, each photosite must be covered with a coloured filter which can be red, blue, or green. These are the three primary colours which can be combined to produce any other colour including white.
The coloured filters are arranged in a grid so that there are twice as many green filters as there are red or blue. This is because the human eye is twice as sensitive to green light. Filters are arranged in a pattern called the Bayer pattern - one row of red, green, red, green (etc.), and the next row of blue, green, blue, green (etc).
Since each photosite can only be covered with one coloured filter, computer processing is necessary to produce a full coloured image. This is done by analyzing each individual pixel and its immediate neighbors and producing a composite colour from these calculations. For example, if a bright red pixel is surrounded by bright green and bright blue pixels, the bright red pixel must actually be white, because white is the combination of red, blue, and green. This process is called demosaicing.
After demosaicing the image is adjusted according to the settings on your camera. Most cameras have settings for brightness, contrast, and colour saturation. After these adjustments are made some cameras may also apply a sharpening algorithm to make the image clearer.
Many cameras have the ability to save uncompressed images as TIFF files or raw data. Raw data is the original photosite data even before demosaicing. It can be transferred to a computer for processing with special software that will perform all of the processing functions of the camera but with much greater control.
Posted by DigitalCamera at 12:14 PM | Comments (0)
June 18, 2006
Using Flash
Automatic flash is a great tool for solving common lighting problems, but unless used with care it can create some problems of its own.
The flash is usually integrated into the body of the camera. This is very convenient -- just shoot the camera and allow the flash to come on if it is needed. There are, however, a few problems related to the close proximity between flash and lens.
The most common problem is red eye. Everybody has seen this -- the eyes of people (and even animals) take on a weird red glow. This is caused by the light from the flash reflecting back from the retina of the eye. The thin red blood vessels in the retina cause the red colour.
Some cameras have a flash setting which reduce this red eye effect. This works by firing a short flash before the picture is taken which causes the iris of the eye to become smaller.
Another problem caused by integrated flash is a lack of depth. The reason for this is the even illumination over the entire surface of the subject. Shadows which normally give a sense of depth are eliminated.
Both red eye and flatness can be reduced with a separate flash unit. They can be powered with a 'hot shoe' (a bracket on the camera body) or a cable which synchronizes the flash with the built-in flash of the camera.
By moving the source of the flash away from the lens, added depth is created and the subject's eyes are not directly illuminated. External flash units also give you more options for aiming the flash -- the light can be bounced off other objects for a more subtle effect.
Not all flashes are created equal. They are available in various strengths, and the power of the flash determines how much area it can light up. Most manufacturers specify the maximum range of a flash. This distance can be achieved when the aperture of the camera is fully opened.
Objects which are closer to the flash will appear brighter. This effect can be used for separating your subject from the background, but it can also create problems if you wish to capture several people or objects which are at various distances from the camera. The only solution to this is to pose your subjects so that they are all at the same distance from the flash.
Creative use of the flash settings can allow you to achieve special effects. For example, slow sync mode can be used to blur the background of a picture while keeping the subject sharply focused. This is achieved by moving the camera slightly after the flash has fired.
Posted by DigitalCamera at 12:16 PM | Comments (0)
June 17, 2006
Memory Cards
Traditional photography uses film as a storage medium. When one film is used up, simply take it out and pop in a new one. The film is eventually developed and the stored images printed. Digital photography also has a form of removable storage - memory cards. The advantage of these cards over film is that they can be erased and reused. Images stored on memory cards can be transferred to a computer for further processing and permanent storage, or they can be transferred directly to a printer. Memory cards are not the only medium for image storage, but they are the most common. Other storage media include removable hard drives and optical disks.
The most common type of compression is JPEG, but this is a 'lossy' format. This means that some of the data that makes up your image is discarded and cannot be retrieved. For most purposes this loss of data is not critical to the quality of the image and the savings in terms of storage space more than compensate for the lost data. Sometimes, however, lossy formats are not acceptable so the image has to be stored without any compression at all. This requires significantly more storage space than JPEG.
CompactFlash
CompactFlash is the most popular type of memory card for digital cameras. It is relatively inexpensive and is widely available. It is used by a number of different camera manufacturers, so if you buy a new camera, chances are it can use CompactFlash. There are two kinds of CompactFlash cards -- Type I and Type II. Some cameras can only accept one type, so it is important to know which one you need for your camera.
Secure Digital / MultiMedia Card (SD/MMC)
SD/MMC cards are the smallest type available. SD/MMC are identical except that SD cards have a write-protect switch which prevents images from being accidentally erased. They can be used in ultracompact cameras and also in personal entertainment devices like MP3 players. SD/MMC cards have less maximum storage capacity than CompactFlash cards (currently at 1 GB) but still offer enough space for most digital photography needs.
xD Picture Cards
xD Picture Cards are also very small -- less than 1 inch square. They were developed by Olympus and Fuji and are most commonly used in those brands of camera. They can be used in other types of cameras with a CompactFlash adapter.
Memory Stick
MicroDrive
A MicroDrive is an actual hard drive housed in a CompactFlash Type II casing. Because they are mechanical drives with moving parts, they are somewhat more delicate than flash memory cards. They must be handled with care and are more prone to breakage. MicroDrives also have a slower access time than CompactFlash cards, but have the advantage of larger storage capacity at cheaper prices.
Posted by DigitalCamera at 12:18 PM | Comments (0)
June 16, 2006
Advantages of Digital Photography
Digital technology is finding a place in almost everyone's lives. From digital music to digital movies we are constantly exposed to images and sound that have passed from the traditional analog domain into the new digital formats. Digital photography is one of those formats and is becoming more popular every year.
For many people, the biggest advantage of digital photography is that it eliminates the need for picture processing. No more trips to the photo store – pictures can be viewed almost instantly on the display screen of the camera. Since there is no developing, digital photography doesn't need dangerous chemicals that could end up in our water supplies.
Another big advantage of digital photos is the ease with which they can be edited. Computer software allows digital images to be altered in any way imaginable. They can be cropped, the colours can be changed or enhanced, the contrast can be adjusted, imperfections can be removed, and images can be combined to create startling new designs. All this can be accomplished in a few seconds with just a few key strokes or mouse clicks.
Using a digital camera is the best way to take advantage of all the features of digital photography, but you can also use a traditional film camera and convert your negatives to the digital domain. If you are uncertain about whether or not to take the digital plunge, converting negatives allows you to get a taste of the wonders of digital photography without investing in new equipment. Most photo developing stores offer this service.
All this must come at a hefty price tag, though - right? Wrong! Digital photography is becoming more affordable every year, and the technology to make fabulous photos is well within the reach of the average consumer. Add in the money you'll save in development costs and you have an affordable, practical, solution for all your photography needs.
Posted by DigitalCamera at 02:32 AM | Comments (0)
June 15, 2006
Aperture
Digital photographs are the result of light hitting the image sensor. Too much light and the photograph will be washed out. Too little light and the photograph will be too dark. The shutter determines how much light enters the camera, and there are two settings which are related to the shutter -- aperture and shutter speed.
Each f-number allows twice as much light to enter the camera as the previous f-number. For example, f/8 produces an exposure which is twice as bright as f/16.
Aperture settings have two basic effects -- the amount of light which strikes the image sensor, and the 'depth of field'. Depth of field refers to the length of the image which is in focus. Large aperture settings have a shallow depth of field -- this means that the focus of an image is relatively short which causes foreground and background objects to appear out of focus. Small apertures have a deep depth of field -- almost all the objects (foreground and background) will remain in focus.
Aperture is directly related to shutter speed for determining the amount of light that enters a camera. Large apertures combined with fast shutter speeds let in the same amount of light as small apertures combined with slow shutter speeds. Determining which combination is best for a particular situation requires photographic judgment that comes with experience.
To make it easier, most cameras have an automatic setting which will do the calculations for you. Many photographers, however, wish to control aperture and shutter speed for artistic effect.
Since a large aperture can be used in conjunction with a fast shutter speed, this is often a good combination for action shots because the fast shutter speed will 'freeze' the motion with a minimum of blurring. Large apertures can also be used for low light conditions where there is very little movement in the scene. In this situation you would combine the large aperture with a slow shutter speed.
Simple point-and-shoot cameras usually have a fixed aperture, and it is only with more expensive models that you have adjustable aperture settings. When choosing a digital camera, one consideration should be the aperture range. There are several ways this can be expressed in the camera specifications: maximum aperture, aperture range, maximum wide-angle and maximum telephoto apertures.
It is more useful to know the aperture range of a particular camera rather than the maximum apertures. A larger range gives you more flexibility in the kinds of shots you can take. A good range for all-purpose photography is from f/1.8 to f/16.
Posted by DigitalCamera at 12:35 PM | Comments (0)
June 14, 2006
Digital Photography Lighting
A photograph is essentially a record of the light conditions at a certain point in time and space. We recognize the patterns of colors and shapes in a photograph because they resemble what we see in daily life. Light is so common that we take it for granted, but the photographer (and the painter) needs to be attuned to the subtlety of light in order to make effective pictures.
Objects have different colors because they reflect those colors while absorbing the others. Black absorbs all color – it is the absence of colour.
Even though all light may look alike to us, different light sources emphasize certain parts of the color spectrum. Bright sunlight from about 10 am to 2 pm, for example, has a bluish tinge. Early morning and late afternoon sunlight is red because it is filtered through the earth's atmosphere.
Artificial light also has distinct color characteristics. Incandescent light brings out red colors while florescent light is greenish-blue.
The photographer can take advantage of these different characteristics when taking shots. Either the camera can be adjusted to compensate for the light source or the special characteristics of the light can be used for artistic effect.
Most digital cameras can be adjusted for color balance. There may be several options – auto, manual, daylight, incandescent and flash. They can be used to compensate for the light source so that white is truly white. This allows the colours to be reproduced accurately.
In some cases you may wish to get a special effect by altering the white setting to a different colour. You can preview how this will look on the LCD monitor.
The direction of the light source is a very important consideration in photography. Light can come from above, behind, below or the side of the subject and each produces a different effect. Generally speaking, a diffuse light coming from the sides will be a good starting point when photographing people. This kind of light occurs in the early morning and late afternoon, or can be produced in the studio with an umbrella reflector.
Of course, all kinds of special effects can be produced by lighting your subject in different ways. Backlighting can create a halo effect, while overhead lights can create strong contrasts between light and shadow.
Posted by DigitalCamera at 12:36 PM | Comments (0)
June 13, 2006
Transferring Digital Images
After you have taken enough photos to fill out up your memory cards you need to transfer them to a computer or printer. There are several ways to do this.
Rather than reading the images directly from the camera, they can also be read from the memory card. Most multimedia notebook and desktop computers can read cards directly. If this is not the case you may need an external card reader.
Card readers are one of the most efficient ways to transfer images. Simply take the card out of your camera and pop it into the reader. Most card readers have a variety of ports designed for different kinds of memory cards. Card readers are almost always equipped with USB 2.0 or FireWire -- an equally fast data transfer protocol. They are quite reasonably priced.
One of the advantages of USB devices is that they can be connected to the computer while it is turned on. The computer will recognize the card reader as an external storage device and allow you to transfer data to any location on the computer's hard drive.
Other Options
For most people, storing images on a computer hard drive is the most practical solution. Computer storage allows images to be edited, sent as e-mail attachments, or posted to a web site.
However, there are other ways to download images from your camera. Cameras with a PictBridge or USB Direct Print can be connected directly to a compatible printer for direct printout. This is a very convenient way to download pictures but by doing so, you miss out on the opportunity to edit them on the computer.
Another way to transfer images is to use the camera's video output to connect it to a TV, VCR, or DVD burner. Images could be captured on videotape or burned to DVD, or simply viewed as a slideshow on a TV screen. Some cameras are equipped with an infrared remote control which allows you to flip through the pictures from your armchair.
Portable Storage
These devices have an internal hard drive and are powered with rechargeable batteries. They read the camera's memory cards so that they can be erased and used again. They are often equipped with a LCD viewing screen so that images can be previewed. Images are transferred to the computer by USB 2.0 or FireWire.
Posted by DigitalCamera at 12:41 PM | Comments (0)
June 12, 2006
Shutter Speed
A camera shutter is a mechanical device which permits light to enter the camera body for a specified period of time. The longer the shutter is open the more light enters the camera.
Many digital cameras have an automatic setting to determine the appropriate shutter speed or it may be set manually for greater artistic control.
Shutter speed is always calculated in relation to 'aperture' – the size of the opening of the lens. These two settings are used in conjunction to control the amount of light that hits the image sensor.
Fast shutter speeds are used to 'freeze' action. Longer shutter speeds can be used in low light conditions and to allow moving objects to blur. This effect is often used when photographing running water.
Since a fast shutter speed lets in less light than a long shutter speed, it is usually combined with a larger aperture setting to allow sufficient light to reach the image sensor. Similarly, long shutter speeds are combined with small apertures.
Shutter speeds are measured in fractions of a second in an approximate 2:1 scale starting with 1 second. The scale runs 1 second, 1/2 second, 1/4 second etc. down to the fastest speed of 1/8000 second. In addition, many cameras have a 'B' shutter setting (the shutter stays open as long as the button is pushed) and a 'T' setting (the shutter stays open until the button is pushed again).
Aperture settings are also measured on the same 2:1 scale. This allows for the same light exposure by increasing shutter speed one notch while opening the aperture one notch. Light conditions for a given scene allow for a range of shutter speed/aperture combinations. There is no 'correct' combination – it depends on what kind of effect the photographer hopes to capture.
For example, if you wish to photograph a moving subject such as an athlete during a sports competition, you would normally use a fast shutter speed to freeze the action. This fast speed must be used with the correct aperture to expose the image correctly.
A slower shutter speed, however, could be used if you pan the camera to match the movement of the athlete. This can create a more dynamic effect as parts of the picture (especially the background) will be blurred. Slower shutter speeds must be compensated for with smaller aperture settings.
Flash adds another dimension to the aperture/shutter speed equation. Interesting effects can be achieved by using flash to freeze the main motion while allowing some of the action to be blurred with a slower shutter speed.
Posted by DigitalCamera at 12:44 PM | Comments (0)
June 11, 2006
Color Balancing
The human eye can easily adapt to different light conditions so that objects maintain their 'true' color. If we look at a blue ball, for example, we see the same shade of blue indoors and outdoors and under cloudy or sunny conditions.
Each type of artificial light also has a particular color cast. Incandescent lighting is yellowish and fluorescent lighting can be either blue or green.
All of these different lighting conditions affect the color balance in photographs.
Most digital cameras allow you to adjust the color balance for different types of light. This can be done manually or automatically, although the automatic settings can produce uneven results from one picture to another.
Manual settings can be done by selecting a preset such as 'sunlight' or 'cloudy', but these settings can be fine-tuned to match very specific lighting conditions.
Color balance is achieved by adjusting the camera so that 'white' is truly 'white'. Once the camera is set to correctly reproduce white, the other colours should appear to be their natural shade. This can be quickly checked by looking through the viewfinder of your digital camera. Holding up a piece of white paper in front of the camera will allow you to see whether it is the correct shade or not.
Some cameras can be set this way -- place a sheet of white paper in front of the viewfinder and select 'Auto Correct'.
Remember that the presets are general guidelines and may not be suitable for every type of lighting condition. If your camera has a setting for florescent lights, for example, it may still require further tweaking to get the correct colour balance.
Although it is best to try to get the proper color balance when you are taking photographs, the colour of an image can also be adjusted using software. This should not be thought of as an alternative to proper color balancing, but it can be used to good effect on some digital images.
Some computer software can automatically adjust color as well as brightness and contrast. Start out with these 'auto' settings -- sometimes the results can be surprisingly good.
If you wish to adjust the color manually, some knowledge of the physics of color is necessary. All color is made up of the three primary colors -- red, green, and blue. Three other colors called the 'subtractive primary colors' are obtained by removing one of the primary colors where the other two are mixed. The three subtractive primary colors are yellow, cyan, and magenta.
Posted by DigitalCamera at 12:46 PM | Comments (0)
June 10, 2006
Printing Digital Images – Part One
Digital photography has put the process of developing pictures into the hands of the consumer. This also includes printing -- anyone with a decent printer attached to their computer can print out their own photographs.
In the process of transferring images to your computer, some software packages automatically downsize the pictures to make them easier to send by e-mail or post on web sites. For printing, however, downsizing should be avoided. Always make sure you are transferring images to your computer at their full resolution.
Even at full resolution, however, some cameras do not have enough pixels to make decent printed pictures. Photo processing shops print pictures at 300 pixels per inch, and if you want that same kind of quality you must have images that are at least that resolution.
Pixels (picture elements) are the individual dots that make up a digital photograph. Cameras are usually rated in megapixels (millions of pixels) - the total number of pixels a camera can record. A camera which is rated at six megapixels, for example, can capture images which are 3008 pixels high by 2000 pixels wide.
The number of pixels in any digital image is fixed, so increasing the size of a photo means there are fewer pixels per inch. If the image is blown up beyond the standard of 300 pixels per inch clarity and sharpness will be reduced. Photos from cameras rated at two megapixels can be printed as large as 5.8" x 3.8" at 300 pixels per inch. A four megapixel camera can print photos as large as 8.2" x 5.4".
The first step in getting good-quality prints, therefore, is to make sure your images are at the correct resolution – at least 300 pixels per inch.
Editing
One of the advantages of digital photography is the ability to edit images before they are printed out. There is a problem, however, with editing JPEG images -- each time they are resaved they lose a little bit of data. This means that if you make several edits to a JPEG file, and save the file after each edit, the quality of the image will decrease significantly.
In order to avoid this, try to minimize the number of edits to a JPEG image to one or two and save the edited image under a new file name. This will keep the original file intact. Alternatively, store the images in an uncompressed format like TIFF. This allows you to do as many edits as you wish without any loss of quality.
When it comes time to print out your pictures you have two basic choices -- print them yourself or send them to a photo processing shop. Many photo shops have an online service which allows you to upload photos to their server. When they are printed (which can take as little as one-hour) you can pick them up or have them mailed to you. Alternatively, do it the old-fashioned way – take your pictures directly to the shop. Photo processing shops may have computers that you can use for free to edit your pictures before they are printed.
You can also print your pictures at home – that's the subject of the next article.
Posted by DigitalCamera at 12:51 PM | Comments (0)
June 09, 2006
Printing Digital Images – Part Two
Most people who own a computer have a printer that goes along with it, and this printer is most likely capable of printing out digital pictures. Here are a few tips to get the best results when printing your own photographs.
When choosing paper for printing digital photographs, you may be tempted to select special archival paper which is reputed to prevent photographs from fading for 20 years or longer. This paper is quite expensive, so before laying down the bucks consider this -- the zeros and ones that make up a digital image will not fade over time. You can always print the picture again to recapture its original brilliance.
That is not to say, however, the paper is not important. You need to use specialized photographic paper that is designed for inkjet printers. It is available in different finishes from glossy to mat. Store it in a cool place away from direct sunlight. Photographic paper is more expensive than regular printing paper, so it is a good idea to minimize waste. Photo printing software can help you to position photos on a sheet of paper so that the maximum area is being used.
Ink is also quite expensive. To avoid wasting it, make the proper settings on your printer for the type of image you are printing. If you are printing a picture which has a resolution of 300 dpi (dots per inch), for example, there is no need to use the 'high' or 'best' printer setting – 'normal' is sufficient. When the printer is set to 'high' it uses more ink and will not produce noticeably better prints as long as you are printing at or above 300 dpi.
How can you tell if your picture is 300 dpi? This can be calculated by dividing the dimensions of your image (in pixels) by 300. For example, if your image is 3000 pixels wide by 2100 pixels high, the maximum size the printout can be (at 300 dpi) is 10" x 7". You can print pictures larger than this (down to about 200 dpi), but in this case you want to select the 'best' printer setting to achieve a good printout.
Dedicated Printers
An alternative to using your regular inkjet printer for printing photos is to get a dedicated photo printer. These use a different printing technology that produces high-quality pictures. The downside to dedicated printers is that they are usually limited to a maximum print size of 4" x 6". They are, however, quite small in size and easily portable.
Dedicated printers use thermal-dye technology. Dye is transferred from a ribbon to the plastic coating of the paper and the resulting picture is more like a traditional photograph than the ones produced by inkjet printers. They also tend to last longer than inkjet printed pictures because of the way the ink is laid down on the paper. Each colour is printed as a separate layer and there is a finishing overcoat which can protect the image from deterioration.
These printers are easy to use and may include simple picture editing functions. They can print pictures directly from your digital camera or memory card, and battery operated models can be used anywhere.
Posted by DigitalCamera at 12:53 PM | Comments (0)
June 08, 2006
Preview Screens and Viewfinders
Traditional cameras use viewfinders which allow you to set up your shot and, in the case of Single Lens Reflex (SLR) cameras, focus your subject. Viewfinders can also be found on digital cameras, but in addition, almost every digital camera is equipped with a LCD preview screen.
Another reason for using the viewfinder is that LCD screens can be difficult to see in bright sunlight. There are many other uses for preview screens, however, and they are essential for most digital photographers.
Preview Screens
Even if the preview screen is not used for composing shots, it still provides a number of useful functions.
If you are running out of space on your memory card and wish to take a few shots more, previewing saved images allows you to pick out pictures which can be deleted. Some cameras have a thumbnail function which allows you to view many shots at once. This makes it easy to zero in on one particular photograph.
For those who print pictures directly from the camera, the preview screen allows you to select which picture should be printed. Some cameras even have basic editing functions which allow you to crop images and adjust colour and brightness before printing them. These functions can be accessed with the LCD preview screen.
Viewfinder
If your digital camera has a traditional style viewfinder, it should be used for most of your picture taking. As we mentioned above, using the viewfinder instead of the LCD preview screen will save on battery power. It will also allow you to hold the camera steadier and move the camera smoothly for action shots. Photographers who wear glasses can get a camera with a diopter adjustment -- this adjusts the lens of the viewfinder so that you don't have to wear glasses when shooting pictures.
There are some situations, however, when using the preview screen instead of the viewfinder is recommended.
The viewfinder is slightly offset from the lens. In most situations this is not a problem, but for close-up shots there can be a noticeable difference between what the lens sees and what the viewfinder sees. The preview screen allows you to precisely compose close-up shots because it shows exactly what the lens sees.
Another time it is better to use the preview screen is when shooting objects close to the ground. This saves you from having to get into an awkward position in order to set up the shot.
Through the Lens Viewfinder
Some of the more expensive digital cameras have a viewfinder which is connected to the lens with a prism. This allows you to see exactly what the lens sees. A variation on this type of viewfinder is the electronic viewfinder (EVF). This is a miniature LCD display which collects light from the lens area. As you are setting up a shot you can also see all of the camera's menus. This lets you change camera settings as you are viewing a scene for immediate feedback. Used in conjunction with a diopter adjustment, this saves the photographer using reading glasses in order to adjust the camera.
Posted by DigitalCamera at 12:55 PM | Comments (0)
June 02, 2006
Imaging Problems – Part Two
Noise is the most troublesome imaging problem but it is not the only one. Other problems related to colour, contrast, detail and sharpness may also be experienced.
Most cameras can be set to automatically adjust the white balance. This setting is usually the most appropriate but for tricky light situations the automatic setting may be turned off to allow the photographer to manually adjust the camera. This can also be used for artistic effect -- a white balance set to an extreme can produce weird, unearthly colors.
Most of the time, however, accurate color reproduction is desired. Inaccurate colors can be compensated for with imaging software, but it is always good practice to capture the best colors at source.
Improper exposure times can also be corrected with software, but again, it is better to try to capture the best image possible. If you have the opportunity to re-shoot a scene which has been improperly exposed, by all means go ahead and try to improve the image. However, if the scene cannot be re-created, save the image and try to work on it with software.
Of all the imaging problems, those caused by poor quality lenses can be the most difficult to correct. Quite simply, a bad lens is going to give you bad images. That is why it is essential to choose a digital camera with the best quality lens you can afford.
However, even good quality lenses can produce distortion at their extreme focal lengths. This is usually easier to correct as the distortion will most likely be in terms of inaccurate horizontals and verticals. Imaging software can be used to compensate for minor variations in straight lines, and the slight irregularity in these situations are sometimes not at all unpleasing.
It is almost impossible, though, to clear up a blurry image caused by a cheap plastic lens. If image quality is important to you, be sure to get good-quality glass lenses and keep them well maintained. Dirt and dust on lenses can cause distortion and noise in the final image, so keep them as clean as possible without excessive handling. A soft brush and a blower should be all that is needed if the lenses are kept covered when not in use.
Most of the imaging problems discussed above can be fixed using software. Professional imaging software such as Photoshop can be used to correct color irregularities, white balance, lens distortion, incorrect exposure, and blurring. Although Photoshop has a steep learning curve, many of the same functions are available in other software packages which are easier to use and less expensive.
Digital photographs, after all, are computer data which can be manipulated down to the bit level, so it is always possible to change the minutest detail of any image. Software can automate many of these corrective functions, and manual manipulation is also possible to improve any digital image.
Posted by DigitalCamera at 01:00 PM | Comments (0)
June 01, 2006
Imaging Problems – Part One
Many people have unrealistic expectations of digital photography. They may believe that digital photographs are 'perfect' in terms of color and detail. In fact, many problems can occur -- some of them are an inherent part of the digital domain, while others can be caused by incorrect settings on the camera.
Traditional photographs also have imperfections which have come to be an accepted part of the photographic medium. Film grain is a pattern of noise which is created by the film emulsion and is often used for artistic effect. Digital photography is expected to be much 'cleaner' than film, however, so noise levels have become an important measure of the quality of digital images.
There are several different sources of noise in digital photography. It is essentially a byproduct of the process of converting light into digital numbers. The individual photosites which make up an image sensor function by converting photons into electrons, and because of the somewhat random fashion that photons arrive at the photosites, the conversion to electrons can produce unwanted artifacts.
Noise can also be produced during the amplification of the electrical signal produced by each photosite. Because the electrical charge is so small it must be amplified to a usable level. The noise produced during amplification can be thought of as 'static' similar to that found in radio broadcasts, although in this case the static produces visual artifacts.
Reducing Noise
There are several things you can do to keep noise to a minimum. It is most noticeable in shots with extended exposure times or high ISO settings. ISO settings are related to film 'speed' -- high-speed film can capture images at very short exposure times. This is ideal for action shots such as athletic events. High ISO settings in digital cameras, however, produce more noise than low ISO settings.
Similarly, long exposure times also introduce excess noise. Long exposure settings can be used to take pictures in low light conditions such as dimly lit interiors. Keeping ISO settings low and exposure times relatively short will minimize noise as you take photographs.
Removing Noise
Noise can also be dealt with after the photograph has been taken. There are several software packages which are specifically designed to remove noise artifacts. They work by applying 'camera profiles' to reduce noise typically caused by specific camera models. Noise reducing software is easy to use and relatively inexpensive.
The problem with camera profiles, however, is that they will never exactly match the noise produced by your specific camera. In order to get the best noise reduction possible, a very simple technique can be used.
After taking a photograph which you expect will be affected by noise, take a second photograph with the same camera settings. This second photograph must be completely black -- the camera shutter must be closed, the viewfinder covered, and ideally the camera will be placed in a bag to prevent any light from entering the camera body.
This second photograph can be used as a 'noise profile' that will almost exactly match the noise of the first photograph. The noise profile is used in photo editing software such as Photoshop to subtract the noise from the first photograph. The best results will be obtained with RAW files, but the technique can also be used for JPEG images.
Posted by DigitalCamera at 12:57 PM | Comments (0)
