It's because when you reach 9999 frame number, your camera won't fire anymore. You have to reset numbering (or create a new folder).

From my Canon user manual:

• Even if the memory card still has space, shooting is not possible beyond file number 9999. If this happens, follow the instructions on the LCD monitor and hold down the <SELECT> button and turn the <rear> dial to select [OK]. A new folder will be created and you can continue shooting.
To prevent any interruption in shooting, set the file numbering method to [M-Reset] beforehand.
• If the memory card in use has a DCIM folder, the file numbering might continue from the last image saved in the folder.


This is a feature and not a bug!
:cool:  :cool:  :cool:

Francois

I just noticed a peculiarity of the EOS 1Ds Mk II "frames remaining" counter: when nearing the maximum picture number (9999), the remaining frames number will display not the frames remaining on your memory card but the frames remaining until number 9999 has been reached ie if you're shooting frame number 9990 with a fresh 8GB card in, the frames remaining will show 9 rather than 440.

Got me confused for a while.

I batch rename every image I shoot because I typically use two bodies when shooting events and prefer to present proof galleries in chronological order. Once the counter gets above 5000 or so, I manually reset it to avoid the aforementioned hassle in the thick of a shoot.