What Flash mode do you use when shooting flash at a wedding Manual, or TTL or both ? I usually put my camera on manual and my Flash on TTL. I look at the distance gauge on my Flash(Canon 580 EX II) to determine when I'm in range then I fire away. However I'm not too crazy about the results and I'm thinking about going Manual. In one book I read recently, the author recommends putting the flash on Manual at 1/4 power f5.6 @ 1/125 sec then firing some test shot to see if you are in range. This is OK if you are shooting still subjects, or Portraits but at a busy wedding I would think that you also need to take the guide number into consideration. Back in the days of film the formula was (guide number divided by flash-to-subject-distance). i would expect this formula to still be viable except that in the age of Digital you are dealing with a varying ISO. Is there an easier way to use manual flash or do I have to start taping a little chart on my flash unit ?