What is a Raw file? Why should I use Raw?
If you have previously been using a compact digital camera, all your pictures were probably saved as JPEG files. Your DSLR camera can produce these files as well, but it also offers the choice of producing Raw files. So what is a Raw file, and why would you want to use it instead of the JPEGs you are used to?
When you take a picture, the camera's sensor records a vast amount of data, far more than is required just to make a JPEG file. When the camera processes the image, it has to discard a lot of that data, in order to produce a smaller file. The resulting image will be fine for most of the uses you might want to put it to, such as printing or sharing the image by email or on a website.
Unlike a JPEG file, a Raw file has not been processed or compressed by the camera. It contains all the data the sensor recorded when it took the picture. This includes a much wider range of colours and tones than would be used in a JPEG, and may also have much more detail in the extreme shadows and highlights. For this reason it is sometimes called a 'digital negative'. And just as developing and printing your own pictures in a darkroom enables you to produce far better results than you can get from your local photo store, the extra data recorded in the Raw file can be used to achieve higher quality images. All it takes is a little practice
To process Raw files, you require a special 'raw converter' software such as the Image Data Converter SR supplied with your camera.
When you open a Raw file in the Image Data Converter, it initially displays the image as it would look if you applied the settings that were on the camera at the time it was taken. You can then make changes to the exposure, white balance, colour mode, contrast and a variety of other settings, until it looks just the way you want. You can even display the 'before' and 'after' images side by side, so you can see the effect you are achieving. And you don't have to worry about getting it wrong. When you have finished adjusting the picture, you can save the result as a new TIFF or JPEG file. The original Raw file remains completely unchanged, so you can come back to it later and make a completely different set of adjustments if you wish.
Examples of what you can get by choosing RAW instead of Jpeg:
In this example, you can clearly notice that the droplets of water hitting the floor are not detailed on the JPEG picture. Also, the overall picture lacks very much details in highlights.
The RAW picture demonstrates that much more detailed can be seen on a picture, making it more intense.
Image taken in JPEG mode
In this example, the picture was taken at the end of the day, at sunset. The red light ambiance only lasted a few minutes. The challenge is to recreate this red ambiance in the picture. In jpeg mode, the picture is underexposed and the colours are dull. This picture is has nothing special
Adjusted RAW file
Contrast, Saturation and Sharpness
These features all affect how your final image will look.
It is not really possible to judge these factors by eye on the monitor screen of your camera, so before making a decision on what level of contrast, saturation and sharpness you wish to use, it is best to take a few images at the different settings and download them to your PC so you can study and adjust them in detail.
Contrast governs how the different shades of dark and light appear in the image. If the contrast is low, everything appears in shades of grey, whereas high contrast has very pronounced highlights and shadows with few intermediate tones. There is no 'ideal' amount of contrast. It will depend on the nature of the scene you are taking. When photographing documents for example, you might decide to increase the contrast to make the text stand out better from the background. Contrast is particularly important if you are using the B&W setting. However, for the best results it is always preferable to shoot in Raw mode. Click here for tutorial information about Raw mode.
This basically means the intensity of the colours. If you have previously been using a compact 'point and shoot' camera, you may initially find the results from a digital SLR are not as colourful as you expected, because compact cameras are often set to a higher 'normal' saturation level. As with contrast, the choice really depends on the sort of picture you are taking. A children's party for example, with lots of colourful decorations and paper hats, will often benefit from a higher saturation setting, whereas if you are taking wildlife pictures you will usually want to match the original colours as closely as possible. It is very important that you base your choice of saturation on studying images on your PC, because the range of colours available on the camera's LCD monitor is not wide enough for you to make a judgement.
This has nothing whatever to do with focusing. If the image is not in focus to start with, the Sharpness control cannot help you.
The process of making a digital photo results in an image which is slightly 'soft'. This is because you are making up complex shapes, using elements (the pixels) that are more or less square. Anything that is not a simple horizontal or vertical line will have a jagged edge. For example, if you wish to delineate a circle, you will actually end up with something that looks more like a gearwheel. When the image data is processed, the jagged edges are smoothed out, and sharpening is then applied. You can select the degree of sharpening to match the subject. A portrait for example, may benefit from being slightly diffused, whereas a picture that contains a lot of fine detail will usually look best with a greater degree of sharpening.
It is also possible to apply sharpening on the PC after downloading your images. If you are taking your picture as Raw files, you will probably prefer to do this. However, JPEG files usually look best if sharpening is done in-camera.
Example of contrast, saturation and sharpness adjustments.
The following picture was taken right after a storm. The sunlight was starting to break through the very dark clouds while in the background you could still see the rain pouring down on the sea. In the first example, the picture is not adjusted. The clouds lack detail, the colour balance is incorrect and the background is missing detail as well.
The challenge is to create a feeling of intense emotion when looking at the picture. Contrast was improved, greys were saturated, and a small amount of sharpening was applied. With much more detail visible in the sky and rocks, the picture is much more dramatic.
What is White Balance?
White Balance enables your camera to achieve natural looking colour under different lighting conditions. The colour of light changes throughout the day, and artificial lighting sources are a completely different colour from daylight. You usually do not notice this, because your eyes adjust automatically, so you can always see colours correctly. However, on a camera, the colour temperature is very visible.
Your camera has a number of different White Balance settings. Depending on your camera models, all these settings may not be available.
When set to auto, the camera adjusts itself automatically, by measuring the colour of the surrounding light. You can leave it at this setting most of the time.
However, Auto White Balance may not always be the best choice. If there is a mixture of lighting conditions, or if you are in one type of light and your subject is in another, it may not be able to adjust correctly. Your camera therefore also offers ways of selecting a specific White Balance to match your situation.
Preset White Balance:
Your camera has the following preset options, which match the most frequently encountered lighting conditions.
This is what we usually regard as 'normal' light, such as we encounter out of doors on a bright sunny day.
This is the sort of light you have in your home. It is more yellow than daylight, and produces a yellow/orange cast if not corrected.
Fluorescent lighting is normally found in offices and shops. It produces a greenish light, resulting in 'muddy' colours in your pictures.
Flash is similar in colour to daylight. Your camera will set for flash automatically when it detects you have the flash switched on, or have attached a dedicated flash unit. However, if you are using 'studio' flash, or a flash unit that does not work automatically with your camera, you will need to set it yourself.
On a cloudy or overcast day, the light is rather blue in colour, and pictures taken in such conditions can appear 'cold'. Using the cloudy setting 'warms up' the colour, so it appears more natural.
Even on a sunny day, if you are in the shade, out of direct sunlight, there is an excess of blue in the light, which can have a similar effect to cloudy conditions.
Each of the Preset options also allows you to make finer +/- adjustments, to tailor the White Balance more precisely to your actual lighting conditions. You can check the effect on the LCD monitor, but for precise adjustments, it is best to download sample images to your PC, so that you can compare them side by side. When using the 'Fluorescent' preset, you can use the +/- to adapt the setting to different types of fluorescent tube (white, warm, daylight etc).
If you find you cannot get natural looking colour with AWB or one of the presets, you can make a Custom White Balance. In this mode you use a white 'target' such as a white card or sheet of paper, to enable the camera to adjust itself to the colour of the prevailing light. The Custom White Balance setting remains in the camera's memory, until you make a new one
Finally, the camera has a Colour Temperature or 'K' setting. Professional photographers often use a Colour Meter to measure the colour of the light they are working in. You can enter the readings from a colour meter into some cameras.
There are some types of lighting that White Balance cannot compensate for. These are the Mercury Vapour and Sodium Vapour lights widely used for street lighting and on industrial sites. The only way to get accurate colours under this type of lighting is to use flash, if the subject is close enough.