Could some-one please explain the difference between AF, AI focus AF, and AI servo AF as pertains to the 300D. Also in which modes (eg aperture or shutter priority, manual, basic functions) can I select these settings and how do I do so? Another question: When selecting exposure lock (asterisk button), I've read that you need to hold this button down until the exposure is made to lock the exposure. However on my camera it seems to keep the exposure locked even after releasing the exp lock button, until the picture is taken. Am I right in assuming that this is how it should be and that the only time you need to keep the exp lock button pressed is if you wish to maintain the same exposure for subsequent pictures?