There is a photo school teacher in the Chicago area led by Will Crockett called Shoot Smarter Not Harder, www.shootsmarter.com. Several years ago while teaching a class, students were editing and erasing individual images as they shot. When they tried downloading into the computer, the entire card was corrupted and everything was lost. In fact the card was worthless and had to be thrown out.

Personally, I have not experienced this problem and occasionally have erased individual images as I shot.

I still do not recommend erasing on site and prefer to wait until all are loaded onto the computer and erase on the computer. I shoot for a studio and I manage the files on the computer. Some of the other photographers have been at a dance photographing couples. As they shoot, they may notice someone blinked and take another shot and then erase.

Unfortunately, I find that the photographer has erased both images of the one couple leaving me with nothing. Or, they the other person blinked on the second shot and he/she did not catch it. If I had both, I could have transferred the open eyes from one photo to the other.

Sometimes, on the tiny screen of the camera (even though they may magnify the vue) they miss something, or due to the pressure of time while trying to shoot many couples in a short amount of time at a dance, mistakes are made.

Then there is the story of a famous wedding photographer who was givin a digital camera by a major camera maufacturer to test out before going to production. He found two problems; one with the camera and one with himself. He went to erase a photo by pushing the button and nothing happened. He pushed the button a second time. Well, this was one of the first pro cameras and it had a slowere processor. If he had waited it would have eventually erased the photo. But, pushing the erase button the second time told the camera to erase ALL the photos. Thanks to his testing, this is no longer a problem with cameras today.

The other problem is that he spent so much time looking at the photos and editing that he was missing many other photo opportunities.

My conclusion, with the large cards available today, the speed of cameras and computers, and the possiblility of human error, it is better to do the editing after downloading onto the computer. If you edit after downloading and accidentally erase the wrong image, it is still on the camera card.

There is no problem "erasing" individual images. Scott Kelby highly recommends deleting as you go.

Otherwise is one of those urban legends.

This may be more than you want to know but: neither "erasing" nor "reformatting" actually removes images from your card. It only affects the "menu" that points to them. They are still there till you take new pics over them. There is software that will let you recover whatever hasn't been written over including from a card that has been reformatted.

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.

This does not damage your card. The only thing it does is 'create virtual holes' and when you take more pictures, fragmentation. For such a small card that has no moving parts it does not make any difference. If you find a slow down after a looooong while, just save everything to your computer, reformat the card and you are back in business. (Note that I would wonder how you would notice the speed difference here)

Only things you have to be concerned about is possible oxidation (rare now a day) and bent contacts when changing cards, also rare if you take a minimum of precaution, like looking at what you are doing.

Too many myths running around.

As to the 'picture is still there' don't worry about that the next picture you take will take it's place so, while the data being latent that space is available. The information is good here ONLY if you want to retrieve an erased picture(s) and only if you did not take a series of pictures before the fearful 'oops!'. Uninteresting computer stuff in a photo forum.