With digital photography becoming increasingly popular, and digital cameras coming down in price, it seems like everyone is shopping for a new digital camera. As a photographer, I get a lot of questions from friends and family about digital photography. I’ve been asked everything from, “What kind of memory cards should I buy?” to, “Why do my pictures look grainy?” or, “What is a megapixel anyway?” Well, here are some answers to those questions, as well as a basic overview of the major elements of digital photography.
Pixels and Megapixels
A digital image is made up of a grid of tiny dots called pixels that correspond to the grid of light-sensitive pixels on your digital camera’s sensor. The resolution of an image refers to how many millions of pixels, or megapixels, it has. The megapixels that a camera offers can be calculated by multiplying the dimensions of the images it produces, so a camera that creates digital images with the dimensions of 2400x3000 pixels has 7.2 million pixels, or 7.2 megapixels.
I can’t count how many times I have been asked, “How many megapixels do I need?” The answer depends on what you plan to use the images for. If you plan to use your pictures only on the computer and online and are not concerned about making prints, you don’t need very much resolution. A 4 megapixel camera will produce images that will more than fill the screen of a 23-inch widescreen monitor (at 1920x1200 pixels). If you would like to make prints up to 8x10 inches, you need more resolution, but 6 to 7 megapixels should be plenty. For larger prints, you’ll want to look into cameras that offer 10 or more megapixels.
Digital Image Format
Another factor that has a lot to do with image quality (though not resolution) is the digital image format you choose to shoot in. Most digital cameras offer multiple choices like JPEG, TIFF and RAW. JPEG and TIFF are file formats that are universal and are compatible with most image editing and viewing programs. Both formats are compressed, which in JPEG results in a smaller file, but can cost you in image quality. In TIFF the compression is “lossless,” but the file sizes are larger, filling up your memory card and computer hard drive faster.
The RAW format is a choice that has become available only in recent years and offers greatly increased quality over both the JPEG and TIFF formats. The name RAW refers to the raw, unprocessed characteristic of the format. Digital cameras take the information from the sensor and process it to produce JPEG or TIFF images, but RAW files are made up of the original image information as it comes off the sensor, unaltered by in-camera processing. Every camera has a different kind of RAW format, so processing RAW files requires special software that can interpret the data. Camera manufacturers provide the software. and many image-editing applications are now supporting RAW formats from multiple manufacturers.
Shooting in RAW allows you to have greater control over things like the sharpness, white balance and exposure of your image. It is the first choice of professional photographers and serious hobbyists. The drawback of RAW is that each file requires more space than the other formats, something to consider when buying memory cards and hard drives (a topic that will be discussed in a future post).
So, hopefully that answers a couple of questions about a few terms you’ll likely encounter in relation to digital photography. Check back next week for a post explaining digital vs. optical zoom, white balance and other (potentially) confusing photo concepts!
