it should probably be mentioned though that a lot of cameras don't have an XLR jack. If the camera you're using doesn't have an xlr jack, you should look into something like a beachtek adapter. Otherwise whether you use xlr or not you'll likely end up with a noisy signal and potentially fluctuating levels.
I generally work with either a 25 foot or 50 foot mic cord, and it's always been enough for me.