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.
- 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
- 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.