Friday, October 28, 2011
Flash Facts - TTL & Manual Metering
For the most part there are two different main ways to meter your flash. TTL metering and manual metering.
TTL stands for 'through the lens'. This type of metering lets your camera make all of the decision for you. What happens is that your camera tells your flash to send out a burst of light. That light is then metered by the camera when it gets reflected back through the lens and into the camera. Once this happens the camera then decides how much power to set the flash to. Then the flash is fired again and the frame is exposed. All of this happens in a fraction of a second. With TTL you will be able to make your decisions about the shutter speed and aperture or you can set everything to auto.
With manual metering you make all of the choices. The easiest way to meter your flash power in manual mode is to use a flash meter. Walk up to your subject and place the meter where you want the brightest exposure at and test fire your flash. You then will get a aperture setting for that exposure. Dial in the settings and take a test shot. Once you have the correct settings dialed in you are good to go.
Both methods have their pluses and minuses. With manual metering you will get the most consistent results. At times the TTL method will vary from frame to frame. Both are good tools to have and I suggest that you become comfortable shooting either way.
If you are just getting your feet wet with off camera flash then I would suggest that you start out in manual metering. With manual metering there are very few surprises and exposure tends to stay put. You can then take what you have learned with manual metering and then give TTL a try and you should be able to predict what is going to happen. Sometime the misses can lead to some fun photography.
All in all don’t get bogged down with the technical side of metering. Give both a shot, make some mistakes and figure out what happened. Eventually you will figure out what works for you and when.