In the dpreview review it says: "As with previous 'Rebel series' cameras the EOS 500D uses its flash for AF assist. If you need to use AF Assist you must pop-up the flash which will fire a brief strobe of flashes (sometimes just one) to help the
AF system to lock." What does that mean? Do I most of the time have to have the flash up? I am new with DSLR and wonder if I most of the time needs the...