MT Shooter wrote:
Bt erasing images in camera you leave empty spots which can lead to fragmentation of the card after awhile. It does not hurt anything, but can reduce the useable capacity of that card temporarily. Fortunately, once you download the photos you kept and reformat the card, you have a clean slate to work with once again. Nothing to worry about now except bending pins.
It does not actually erase the file, it merely makes the space available for writing another file. That is why Computer Forensics can recover "deleted" files. I too think you would be better loading the files onto the computer then purging from there. I was told years ago in a digital camera class that you should reformat a memory card every time you empty it onto the computer. If you don't you are inviting a problem on down the line.