Resolution planning for digital photos
Typically a digital camera has at least three resolution settings--high, medium, and low. Although higher resolution images take up more space on storage cards, use the higher resolution setting whenever possible. If you’re short on storage or memory space, medium resolution is an acceptable compromise.
Always avoid the low-resolution setting, if you want to crop, sharpen the image or correct color and exposures, the higher setting will be beneficial.
Also, even if the image looks acceptable for your current project--you may want to print them in the future. By planning ahead you won’t be disappointed with the quality of the prints.