Memory Cards and External Flash (Also Understanding File Types)
Posted on 14 July 2012
After the digital image sensor has processed the image, the camera will undergo a series of adjustments to optimize the image. Many of these adjustments are based on shooting settings customized by the photographer before taking the shot, such as the ISO setting. After image processing, the camera stores the digital information in a file, which varies depending on the camera’s manufacturer. However, the camera’s RAW file contains the digital image data before it has been converted to a common standardized file type, such as JPEG or TIFF.
There are certain photographic situations that need the additional light provided by an external flash. Many consumer DSLR models have built-in flashes but the proximity to the lens and the lack of flash exposure control prevent their use in advanced situations. External flashes provide professional-level control over flash exposure. This allows for fine-tuned fill flash (low-intensity flash that illuminates the subject against a bright background so the subject does not appear in silhouette) and the prevention of overexposed subjects in close-quarter situations.
Understanding File Types
It’s important to understand the differences between image file types. RAW, JPEG, and TIFF file types are described below.
A camera’s RAW file is an unconverted, bit-for-bit digital image recorded by the camera when the image is captured. Along with the pixels in the image, the RAW file also contains data about how the image was shot, such as the time of day, the exposure settings, and the camera and lens type. This information is also known as metadata. RAW refers to the state of the image file before it has been converted to a common format, such as JPEG or TIFF. Because most photography applications previously could not process RAW files, RAW files had to be converted before they could be used in image processing software.
JPEG (Joint Photographic Experts Group) is a popular image file format that lets you create highly compressed image files. The amount of compression used can be set, less compression results in a higher-quality image. When you shoot JPEG images, your camera converts the RAW image file into an 8-bit JPEG file (with 8 bits per color channel) prior to saving it to the memory card. In order to accomplish this, the camera has to compress the image, losing image data in the process. JPEG images are commonly used for online viewing.
TIFF (Tag Image File Format) is a widely used bit mapped graphics file format capable of storing 8 or 16 bits per color channel. Like JPEG files, TIFF files are converted from RAW files. If your camera does not have an option to shoot TIFF files, you can shoot RAW files and then convert them to TIFF files using third-party software. TIFF files can have greater bit depths than JPEG files, allowing them to retain more color information. In addition, TIFF files can use loss less compression, meaning that although the file gets a little smaller, no information is lost, thus, the end result produces greater image quality. For these reasons, printing is commonly done from TIFF files.
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