RAW files store image data directly from the camera's sensor to the media card with a minimum of in-camera processing. Unlike JPEG images, which you can view in any image-editing program, you must view and convert RAW files using Canon's Digital Photo Professional program or another program such as Adobe Lightroom or Adobe Camera Raw.
You may wonder why you'd choose RAW shooting. RAW files offer the ultimate flexibility and control over the image because you can change key camera settings after you take the picture. For example, if you didn't set the correct white balance or exposure, you can change it in a RAW conversion program on the computer. You can also adjust the exposure, contrast, and saturation — in effect, you have a second chance to correct underexposed or overexposed images, and to correct the color balance, contrast, and saturation after you take the picture. The only camera settings that the Rebel
XSi/450D applies to RAW files are aperture, ISO, and shutter speed. Other settings such as White Balance, Picture Style, and so on are "noted," but not applied to the file. As a result, you have control over how image data is rendered during image conversion. The RAW conversion process takes only a few additional minutes, and then you can save the image in a lossless file format.
RAW files are denoted with a .CR2 filename extension. After converting the RAW data, you save the image in a standard file format such as TIFF or JPEG and work with it as you do with other image files.
On the XSi/450D, you can choose to shoot either RAW images or RAW+JPEG, which records the RAW file and Large JPEG image. The RAW+JPEG option is handy when you want the advantages of having the flexibility that you get with a RAW file, and you also want a JPEG image to quickly post on a Web site or to send in an e-mail.
Because RAW is a lossless format (no loss of image data), image quality is not degraded by compression. However, you can store fewer RAW images than JPEG images on the media card.
With this overview of the differences between image quality settings and file format, you're in a better position to choose the setting that best suits your needs. The image quality settings depend on the shooting mode you choose.
In Basic Zone shooting modes such as Portrait, Landscape, and so on, the camera automatically sets the file format to JPEG, but you can set image size and compression level. In Basic Zone modes, you can't select the RAW format.
In Creative Zone modes —P, Tv, Av, M, and A-DEP —you can select any of the JPEG options as well as RAW or RAW+JPEG.
To set the image quality in both Basic and Creative Zone modes, follow these steps:
1. Turn the Mode dial to a Basic
Zone mode. Basic Zone modes are indicated by icons such as a person's head for Portrait mode, mountains for Landscape mode, and so on.
2. Press the Menu button, and then turn the Main dial to select the Shooting 1 (red) menu, if necessary.
3. Press the down cross key to select Quality if it isn't already selected.
4. Press the Set button. The Quality screen appears with the currently selected quality setting displayed along with the image dimensions in pixels.
5. Press the down cross key to select the size and quality that you want. In Basic Zone modes, you can choose only JPEG options at different levels of compression. A solid quarter circle icon indicates a low compression level. A jagged quarter circle icon indicates a higher compression level.
6. Press the Set button.
7. Turn the Mode dial to a Creative Zone mode.
8. Repeat steps 2 through 6 to set the quality for Creative Zone modes. In these modes, you can also choose RAW or RAW+JPEG file formats.
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