Will older CF cards work with the 5dM3?

I do not have a 5D M3 to test with right now, though does anyone know if older SanDisk Ultra II 1.0GB SDCFH cards or Lexar Professional Compact Flash 1GB 80x Speed cards will work with it for just shooting photos?

Thanks.

I would say they should do.

But nikon has had problem with 1gb cards in the d800.

IF it fits, it probably works, but with limitations. Older cards can of course be smaller but more importantly slower thus limiting the number of images you might get before the buffer fills up.