Exercise in Fill Flash usage

Fill flash is very easy with today’s cameras. The use of TTL flash metering has taken out all the guess work out, and made it available to everyone. Cameras with a build in flash adjust the output automatically for the majority of flash needs. However, Outside, where you want to isolate your subject more from the background, and/or brighten up your subject in the shade, a more powerful flash than the one  built in the camera will be needed. The Built in flash has a Guide Number (GN), around GN: 10-20. Outside, you will need an external flash that has some good power. The GN should be in GN:110 range with your ISO at 100 and a 50mm lens field of view. (M4/3 = 20/25mm, APS-C = 35mm).

GN: 110 at 10’/3m at ISO 100 at 50mm.. This will give you an f/stop of  “f/11” at a 10 foot distance with a 50mm lens.

For outdoor subjects, using a powerful external flash with TTL, and the camera on Program mode OR Aperture mode will be as painless as using the built in flash.

Exercise #1

  • Being a friend a to park or location that can provide a background that is interesting.
  • Bring you camera with a moderate telephoto on it. (you want at least a 100mm fov). A zoom like a 70-200 on a APS-C, or a 40-150 on a m4/3.
  • And your External flash

Set Up:

  • Place friend standing in front of the background… you want at least 50 feet distance between your friend and background.
  • You stand at least 15 feet away from your friend, and use your zoom to frame a 1/2 length pose.
  • Set your ISO to 200
  • Set your camera on “P” mode
  • Set your flash on TTL
  • Take a photo, and check the Exposure, if the friend is lit properly, great. You should get a good exposure.
  • This was to show you that you can trust the External TTL flash outdoors.

2nd Set Up:  (Dragging the Shutter)

  • As above:  with 2 changes
  • Put your flash on “A” Mode
  • Put your camera on “A” mode.
  • Make sure that you pick an f/stop that is close to the subject distance for that f/stops “MAX” distance. (all f/stops will have a “Min” and MAX” working distance with your flash)
  • From the same place, take series of photos at different shutter speeds (1/250, 1/200, 1/125, 1/60)
  • What you will find, is that as you shoot at slower shutter speeds, your friend stays properly exposed, BUT, the background will get darker.
  • This is called “Dragging The Shutter”
  • It can be used to simulate night-time photo, or darken the background, if it is too distracting.