Fill in Flash is a must in harsh sunlight or with a backlit subject!

Fill in flash can literally save a picture that is in danger of having very hard shadows on the subjects face, or being overly backlit meaning the face is underexposed.

It can also simply add a pleasing effect to an already good shot, such as as highlights or catchlights in the eyes.

These photographs were taken at the same time with the camera set to 100th/sec at F.8 for both shots. I simply turned the flashgun on for the second and set it to E-TTL (Auto) mode.

As the flashgun (Sigma EX500 DG Super) is dedicated to the camera (Canon EOS 20D), it worked out when the subject had received enough light and shut off accordingly.

Whilst the shot on the left is backlit by the sun, it isn't badly exposed and the features are well lit. However, with the shot on the right, the detail in the clothes is enhanced, and the faces are brighter with highlights in the eyes.

As to what method you would use in this situation, I would put it down to personal preference. As this was a paid job, I gave the couple the choice of either as it was for publication in a yearly catalogue.

I love backlighting, and fill in flash came in particularly useful at a recent wedding that I shot.

The service was held in very mature gardens in Gibraltar and it was a sunny day. The camera had a hard time getting the correct exposure when it had deep shadows and bright sunlight to contend with.

The only way to do it was to take some test shots of the foliage and get the best average reading (in this case 60th at F5.6 or F.8). Then I kept the flashgun switched on and used fill in for most of the outdoor shots.

Without fill in flash, the shot on the left could have been ruined. The early morning sun was beaming through the trees and with a slight mist around, created these rays of light. The fill in flash pulled out the features perfectly, although a little work was required in Photoshop to "Bring out" the people in the background.

The shot on the right was again, heavily backlit, but this put some beautiful highlights in the hair of the couple. Using fill in flash, I managed to keep the detail in the dress and couple's faces.

If you are unsure, use the normal settings that the camera's meter chooses, and put the flashgun onto Auto or E-TTL and you should be ok. Of course, the beauty of digital is that you can see the results instantly. If you are shooting in direct sunlight, always try to turn the subject so that the sun is behind them, otherwise you will end up with some serious shadows to deal with in Photoshop!

If you ARE shooting a wedding, I would seriously suggest that you go to the venue a week or so beforehand and take some test shots. You don't want to be keeping the couple and guests waiting while you play around with the flash settings!