<p>To understand resolution: http://www.digitaldog.net/files/Resolution.pdf<br>
Yes it's really old! Nothing has changed however. I really DO need to update it as a modern video and cover Lightroom. In the meantime, you'll see that the resolution '<em>tag</em>' is rather meaningless and the way to work is by understanding the number of total pixels you have over hight and width. </p>