with the digital SLRs you can actually set the "film speed". There is an ISO setting on mine from ISO 100 to 1600 (up to 3000 with a firmware upgrade). Just like with film, the higher the ISO, the grainier the picture. You also get all the control if you want it of the shutter speed and aperture so you get creative control of the DoF/stop motion.
I took a photography class in high school, but that was over 20 years ago; so it's time for me to relearn everything :)