Mirror Lockup

Could someone help me with this, is the mirrir lockup samething as Bulb mode? If not what is it and how do I impliment it with my 20D? Thanks in advance

Bulb mode is the ability to fix the shutter open and close it after whatever time you wish. You set that in the shutter speed control (v.g. control wheel if in Tv or M). It is mandatory if requiring shutter speeds longer than the maximum 30 sec that the 20D can do its own timing.

Mirror lockup (MLU) is set to have the mirror open a couple of seconds before shooting so that the vibrations that the slapping produces does not provoke camera shake. BTW, the mirror is what reflects the image from the lens into your viewfinder and it must get out of the way before the shutter (actually curtain) opens in order for the image to get to the sensor. You will want to use it for longer shutter speeds, especially in the 1/15 - 1/8 sec range.

To set MLU, you use Custom Function 12; set to 1: Enable.