Camera objects (aka linked pictures to cell ranges) can considerably increase the size of an Excel workbook. Why?
My good friend and Excel MVP Chandoo also wrote several articles about the Camera Object (all articles with 'camera tool' tag on chandoo.org).
The feature may still not be as known among Excel users as it should be, but there are so many very good tutorials available that I do not need to write another one.
As great as they are, Camera Objects always had a few issues (printing, merged cells, distorting captured charts, etc.) as Charley points out here: A New Excel 2010 Camera Tool Bug, and a Workaround.