Reformatting ensures data and the file structure on the card is intact and without errors. The longer you go without formatting the card, the more likely that the file structure will become corrupt and that you will not be able to read some of the images from the card. Additionally if you don’t reformat your card, it will slowly reduce the number of files it can hold. If you share your card between multiple cameras, the cameras may not recognize each other’s files structure and not allow you to delete images from another camera manufacturer.
Get in the habit of formatting your card after copying your images to you computer and then backing them up to an external drive. You’ll have less errors reading images off of your card and you’ll have the full card capacity to capture your images.
It’s especially important if you have multiple cameras or are migrating from one camera to another. Cameras don’t have a single standard for file formats, therefore if you take a card that was used in one camera, it may not recognize the file format of the other camera and it will erroneously report the amount of free space until you format the card. This will mean you may have very little space available on the card for your images. There’s nothing worse than running out of space on your card when your in the middle of capturing that special moment.
When you format your memory card you will not be able to retrieve the images you previously captured so be sure you’ve copied off all the files first before you format the card, you can’t undo formatting!
It’s also a good idea to not use the same memory card over and over again but to switch between a few cards and always bring a spare along with your spare battery. Occasionally memory cards will go bad and if you are using multiple memory cards you wont loose all your work or and you’ll still be able to capture more images.
Don’t know how to format your memory card? Check your camera manual or your manufactures website to download an electronic version of your camera manual. The steps can be different on each camera. Formatting should be done in your camera and not in your computer.
If your camera offers a low level format, utilize this feature as it will reduce the possibility of file system corruption.
Links to a few camera manufacturer sites which should help you to find your manual:
Canon Consumer Cameras: http://www.usa.canon.com/cusa/consumer/products/cameras
Nikon download center: http://www.nikonusa.com/Service-And-Support/Download-Center.page