Never format the card in the computer. A couple of options. If you are reading the memory card via a card reader (and thus the card appears as a drive on your computer), or you have the camera connected to the computer and it appears as a drive then just like any other files on a computer, select them all (ctrl - A if running windows, I don't know what a Mac/Linux would be) - press delete. Or when the card is in the camera go to your setup menu - format For many if not all Sony cameras, go to playback mode, hit wide on the zoom to go to thumbnails, press the delete button, select all in this folder...
It is a good habit to format your memory cards from the camera. Sure, it's ok, fast, convenient to deleate images from the PC, or individually from the camera; but the way I understand it when you reformat the memory card from within the camera you reset the card's directory structure to save new images sequentially from the beginning of the memory, thereby maximizing the free space available and memory write/access speed. You also minimize the chance of corrupted image files. I do this pretty much every photo shooting session...
I have been critisized for my method, but have never lost a picture using my current or two prior digital cameras and about 8ooo snapshots:.
I use a usb card reader and a Sony camera.
Insert the card, explorer to the active folder on the card.
One mouse click on any photo.
CTL/A to highlight all pictures.
CTL/X to send all to the notepad.
Explorer to computer MY PICTURES CTL/V to paste them all.
Eject the card.
Review pictures on the computer and delete any bad pictures.
Move pictures to final folder (landscapes/crafte/wildlife or current month.) The criticism I hear is that I risk losing pictures if power shuts off or other emergency, but it has never happened and the conveenience is worth the risk...
I'd just reformat the card in the camera, after transferring the pics to a PC (and verifying they transferred correctly). Look for a "Format" or similar option in a Setup or Memory menu. This cleans up the filesystem on the card too, which can get quite fragmented when just deleting...
I would like to know why my canon540 no longer makes the crunch sound when taking a picture? Any ideas. Thanks..