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-------------------------------------------------------------- This story was printed from CNET Asia. --------------------------------------------------------------
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Digital SLR Superguide: Using a dSLR
By Larry Loh,CNET Asia staff
02/03/2007 URL: http://asia.cnet.com/digitalliving/tips/0,3800004921,61992397,00.htm Using a digital SLR? 
Understanding the inner workings of dSLRs Using a dSLR is not just about knowing the basics of photography and applying them. While that is vital, it is also important that you understand a little of what is going on inside the camera, and how to take advantage of it. Once you have mastered this then you can really start to get creative.  Hazy about "white balance" Setting manual white balance The meat on RAW Having fun with white balance
Hazy about "white balance"
Film users will be familiar with the principle of using filters to correct for different light types. For example, incandescent (tungsten) or fluorescent lighting will need to have different filters so that the colors come out true. The reason this is so is due to the fact that different light types give off slightly different colors of light. The human eye can adjust to this so we don’t notice, but cameras record the different colors. This is what is called a "color temperature".
A low color temperature shifts light toward the red (i.e. warmer) while a high color temperature shifts light toward blue tones (i.e. cooler). Different light sources emit light at different color temperatures, and thus the color cast. These affect the way that the camera captures the colors of the object that you are shooting. Most people don’t bother with the filters and so their indoor pictures invariably come out with a yellow/orange orbluish cast. In the digital world, these correction filters are no longer necessary as they are replaced by a feature found in most digital cameras called "white balance". Normally the human eye can compensate for lighting conditions with different color temperatures. However, a digital camera needs to find a reference point that represents white. It will then calculate all the other colors based on this white point. For instance, if a halogen light illuminates a white wall, the wall will have a yellow cast in the picture when, in fact, it should be white. So if the camera knows the wall is supposed to be white, it will then compensate all the other colors in the scene accordingly.
Setting white balance manually
 To set the white balance manually it is necessary to tell the camera which object in the frame is actually pure white (or as close as can be). This allows the software inside the camera to make adjustments to ensure that all the colors are recorded accurately.
Most digital cameras allow the white balance to be set manually. Digital SLR cameras allow you to define your own white balance reference. Before making the actual shot, you can focus at an area in the scene that should be white or neutral gray, or at a white or gray target card. The camera will then use this reference when making the actual shot. Refer to your camera manual for the procedures to carry out custom white balance settings. Ideally, for precise measurements, an accurate reference device would be a Kodak gray card (which is calibrated to 18 percent gray--the basis of most exposure meters in cameras) or an Expodisk. However, out in the field, there’s often no time to do a pre-shoot measurement, and a rough gauge will have to suffice. Use any relatively white area, such as a blank sheet of white paper. Once you’ve selected a white balance setting, just remember to reset this setting when you head back outdoors into natural light, or you may end up with some strange tones and hues to your subsequent images.
The meat on RAW
 A word on RAW--the RAW file format offered by dSLR cameras is probably one of the most compelling reasons to get one. A RAW file is the digital equivalent of a digital negative. It allows you to fine-tune the exposure of your images (up to +/- 2EV either way), adjust your white balance settings, and set the saturation and hue settings without altering the original--unlike JPEG or TIFF formats where these settings are locked in at the time of shooting. Put simply: The RAW format is much more flexible and you get all this and more at a file size that’s typically smaller than a full-size equivalent TIFF file. The RAW format will be discussed in greater detail later (Part 4) in our Workflow section. Most digital cameras feature an automatic white balance mode where the camera processor looks at the overall color of the image and calculates the best-fit white balance. However, like all technology, this is not foolproof. The measurements can often be slightly out especially if the scene is dominated by one color, or if there is no natural white present in the scene.
Having fun with white balance
 Using white balance settings can be a source of creative effects for your pictures. For example, if you’re taking a landscape image of a beach and you want to make the light warmer to create a sunset effect, try setting white balance to Fluorescent. This would effectively tell the camera that the light is too cool. The camera responds by shifting every color toward the warm, red values. Dial in a Tungsten white balance, and the camera shifts all colors toward the cool, blue values, producing a "sunrise" effect. Obviously, there would be a lot of trial and error involved, but the good thing about digital is that you’re free to experiment and review the results at very low cost. The other alternative to getting perfect white balance every time is to capture your images in the RAW file format. When you save an image in RAW file format, you are saving it the way the image sensor sees it--without applying any adjustments (including white balance) to it. In fact, the camera ignores any white balance values entered except as a default setting. In the post-processing phase, using an image-editing software with the appropriate RAW plug-in, you can load the RAW image to JPEG, and apply any white balance values you wish, until you obtain the perfect color balance.
Working with your dSLR Scoping out the lenses and support system for your dSLR Of lenses and support Lens perspective Focal length multiplier Stop that shaking Holding your camera properly Tripods
Of lenses and support
There is a wide and extensive range of lenses and accessories to complement SLR cameras. There are lenses ranging from 14mm fisheye to a whopping 1,200mm lens (available only by special order and certainly not for the weak or fainthearted).
Let’s take a quick look at lenses and what they can achieve. 
Lens perspective
Different lenses can yield different effects based on their focal length and distance to the subject, among other factors.
A lens with a longer focal length will have a "compression effect", where the foreground seems closer to the background. This is very good for portrait pictures, when you want them to stand out from the background. More apparent depth can be created in the picture by using a wide-angle lens, allowing the background to remain in focus. The 50mm perspective is closest to what we see with our own eyes. Using this effect, dramatic effects can be used, for example, using a wide-angle lens to impart a "you-were-there" feel or using a long telephoto to concentrate the focus on a single part of the picture.
Focal length multiplier
The Focal Length Multiplier (or FLM) is probably one the most misunderstood terms about dSLRs. dSLRs tend to have a sensor that is smaller than a 35mm film frame, so images obtained are equivalent to cropping out the center of a 35mm film frame. As lenses are still made with 35mm cameras in mind, the picture angles of various lenses are calculated to reproduce an image on a 35mm frame.
In essence, what the crop factor means is that you're using a bigger lens than necessary for the capture. For example, using the EOS 30D, the focal length of a 50mm lens is approximately 80mm (i.e. 50mm x 1.6 = 80mm). The crop factor has both pros and cons to it. The good news is that you can now achieve super telephoto focal lengths without buying costly and unwieldy lenses. For example, a 100-300mm zoom lens, with a focal length multiplier of 1.6, becomes a 160-480mm lens. The disadvantage is that a 18mm super wide-angle lens is now only about 28mm, making it almost impossible to obtain the kind of super wide-angle coverage that most professionals desire. This has led to the development of special APS-sized lenses, namely the EF-S lenses for Canon and the DX range for Nikon. These take into account the smaller sensors and compensate accordingly, allowing smaller lenses with wide-angle capability to be introduced to the photography community.
Stop that shaking
Camera shake is probably the main cause of blurry photos, due to movement or when too slow a shutter speed is used. There are two ways of minimizing or eliminating camera shake altogether--use a proper support for your set-up or develop a proper handholding technique.
Let’s look at the first option of getting the right support. Choosing the right support There are several options for camera supports, which are mainly: A tripod is probably the most popular choice for photographers. It creates a steady, level platform for a camera and using a tripod almost guarantees that photos will be sharp. A tripod is great for taking close-ups, panning and landscapes. It also serves the purpose of reducing weight of your equipment, especially if you had to handhold your camera and lens for extended periods of time. Stability should be on the top of your list when buying a tripod. It should be lightweight enough to carry, yet strong enough to support your digital camera. With a dSLR system, the weight of your heaviest lens has to be factored in--that’s why it’s common for nature photographers with heavy 500mm/600mm lenses to lug around a big but sturdy tripod. The dilemma of tripods lies herein--the heavier the tripod, the more sturdy it is, but it's also that much harder and bulkier to move around.
Holding your camera properly
 More often than not, a well-developed habit of handholding your dSLR would eliminate many of the problems from camera shake. This is especially essential when using longer telephoto lenses.
Bear in mind the old rule-of-thumb for handholding--the shutter speed should be at least the reciprocal of the focal length of the lens mounted. For example, you can generally shoot at 1/50 sec with a 50mm lens mounted, or at 1/200 sec with a 200mm lenses. Remember to factor in the FLM of your camera, since the sensor concentrates its recording capability on the smaller area, thus amplifying any handshake (i.e. use a shutter speed of 1/320 sec when using a 200mm lens mounted on an EOS 30D). While dSLRs may be a little heavier than more compact cameras, their size and shape do make holding the camera steady much easier. The best way to hold a dSLR is to have the right hand firmly on the grip with the index finger used for the shutter button. The left hand cradles the base of the camera and lens (on the shorter lenses) or the lens alone (on the longer lenses). This will provide a good solid base to shoot from.
Image stabilizers
Some tips on proper handholding
Tripods
 A good tripod is an essential tool for dSLR photographers. It can help in a wide range of situations, from low-light conditions to needing to achieve a steady, level pan across a scene, to helping to support heavy lenses. These bits of kit will be invaluable to the dSLR photographer so it is worth spending a little time looking at what you might want out of them.
What to look for in your tripod: Quality construction Try to avoid tripods which have a lot of plastic parts, particularly mounting screws. Quality tripods are made of metals such as aluminum, lightweight carbon fiber and titanium alloy. While these are proportionately more expensive than other models it is very important to make sure that your tripod is sufficiently well-constructed. The cheaper, lighter models are fine for smaller cameras and undoubtedly do a great job supporting the lightweight compact camera. However, a dSLR will almost certainly be heavier and this can be more than doubled by adding some of the bigger lenses to the mix. Some lightweight tripods simply do not have the strength to hold the camera level or even steady. It is better to put up with a bit of extra weight than to see your dSLR and tripod go crashing to the ground. Quick release This is an extremely useful feature found on most professional tripods these days. A tripod with a quick release mounting platform comes with a plate to attach to the bottom of your camera. This lets you quickly attach or detach the camera to the tripod. This not only makes shooting much easier, it is essential when you are shooting in conditions where you might need the camera steady one moment and then off the tripod and shooting from the hip the next. Height If you plan to use a tripod a lot, it should be tall enough for comfortable viewing. Since you will be carrying the tripod around this may be an area that you can compromise on. If you don’t mind bending over a little to look through the viewfinder then you can save some weight by buying a tripod with slightly shorter legs. Many larger tripods have an extension pole in the middle, which can give you some extra height. However, you shouldn't rely on it too much since anything that takes the camera away from the point at which the legs meet will increase the instability. Easy-to-use, easy-to-adjust controls Once the camera is on the tripod you will not want to spend time working the controls. Just like the legs these should be easy to use and yet once set they should not allow the camera to move at all. Again, there is a wide selection of head types so have a look at the different ones on offer to see which one suits you. The better tripods will come with the option to change heads so you can buy more than one type if you want to. Also make sure that the controls allow you to position the camera both horizontally and vertically, as you will want to take pictures from both angles. Easy to set up The tripods legs should also be easy to extend and reduce, but should lock firmly into place when you are happy with the height. Each manufacturer has its own way of doing this, so have a look at the tripod in the shop to see how the legs work and see if they are suitably easy to use and stable once they are set up. Bear in mind that on uneven ground you may need to shorten one or more of the legs to keep the camera level. Some tripods come with built-in spirit levels (an extremely useful function), but adding a small spirit level (from any hardware store) to your camera bag will also solve the problem. Folds to a manageable size Unless your tripod is primarily for use in the studio, you will need to carry it around with you. It is therefore very important to make sure that the model you choose folds up small enough to be manageable and portable. This is another area where you might find there is a need to compromise between perfect stability and perfect size and weight. Find a happy medium between these factors if you can, but it is generally better to opt for stability over convenience--after all if the pictures don’t come out right then all your effort will have been wasted. |
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Using a dSLR
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