I was going through some images the other day that a photographer had taken outside using a flash on a cloudy day, and noticed a huge problem with them. There was no definition in the sky. The sky looks totally white. I took a look at the meta data and found that the shooter used an aperture of f/4 and a shutter speed of 1/60th to 1/100th of a second. Looking at them I couldn't help but wonder why the photographer forgot one important fact about flash photography. He forgot that when you use flash there are two exposures to take into account. The flash exposure and the ambient exposure. He could have stopped down on the shutter speed to bring those clouds in or even stopped down the aperture and increased the flash power or the ISO (set at 100). Given the camera that he was using he could have gone all the way down to 1/200th of a second on that shutter speed. Another thing I noticed was he was using a flash on a bracket and the flash was pointed straight up. I know these things because I was there when he shot them. When you're outside the flash should be used as a fill flash and pointed straight at the subject when it is on the camera. Another thing that could have been done is to get an inexpensive set of radio triggers, put one on your speedlight, get a friend to hold the light where you tell him to.
Try this next time you're outside. Get someone to model for you and another friend to help you out with the flash if you can. If you can't find someone to model for you get something about the size of a person, and try to get your flash off camera.
Setup and take a properly exposed shot without the flash, making sure your meter is zeroed out for a proper exposure: this will be your starting point.
Setup the flash and take another shot properly exposed for the flash. Your subject should look about the same in each shot.
Adjust the exposures so that the aperture settings in both are equal. For example if the ambient exposure is 1/250th at f/5.6 and the flash exposure is f/8, then you want to make your aperture at f/8 and your shutterspeed 1/125th and take a shot. Note that if your subject is in the same light as the background it may appear washed out. This is because you are, in essence, doubling the amount of light hitting the subject so you need to stop down your aperture to f/11 and set your shutterspeed to 1/60th because the flash exposure is controlled by the aperture.
You now have what I like to call the reference exposure. Now take a few bracketed shots, one with a one stop faster shutter speed and one with a one stop slower shutter speed. This should have no effect on your subject or model but should have an effect on the background. You probably won't notice it so much on the camera display but when you look at it on the computer you should notice the change. Take a few shots with even more drastic changes in the shutter speed and see what you get. Just remember to keep in mind the sync speed of your camera. This should be listed in your camera manual. If you're having trouble getting the shutter speeds you need change your ISO. Just remember if you change one setting you'll need to know how it affects your image so you can adjust your other settings accordingly.
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