Very often people equate wedding journalism with ambient light, but in reality you cannot always get what you expect. The light you require is often absent, is the wrong kind or is in the wrong place. In such situations judicious use of on-camera plays a very significant role in assuring superb shots and happy clients. It is all about complementing the light that is there. When you have a flash mounted always, you can pretty much address any kind of lighting situation. Frequently at a wedding it is a choice between using the flash and getting the picture or not getting the picture at all. In the present world of wedding photography, capturing shots with ambient light is the current fad, equally important is the knowledge when to turn on the flash and buck the fad
That is not to say there are not. There are certain critical choices to be made when using on-camera flash; aside from stylistic and philosophical issues, you might deal with such potential downsides as distracting the wedding party and guests, creating unsightly side shadows, fall off and more. Even then the flash is a very essential tool for any successful wedding photographer, since its characteristics and even its eccentricities could be put to advantage in fully capturing the story of the wedding day.
The beauty of using on-camera flash indoors is in the bounce. This bounce might be the most important factor in creating an ambient feel and providing atmosphere while reducing the evidence of flash. Bounce softens light by effectively making the source larger, eliminating hard shadows and allowing selective enhancement existing illumination. Bounce also unleashes plenty of creative possibilities. Apart from ceilings and walls, even tablecloths and wedding dresses, anything that can reflect becomes a source for bounce. When flash is used indoor, bounce at all times, bounce off ceilings, walls, and people’s white dresses whatever is available in order to increase the effective flash-to-subject distance, to reduce fall-off effects and soften the light source by spreading it out in every direction. If you are bouncing but have nothing to bounce off, a little creativity like a wedding invitation or a menu held above the flash can make for some nice light. Or the photographer can bounce a flash sideways to create side lighting in rooms with very flat illumination. Side bouncing can be very effective for simple portraits, say; the subject is about three feet away from the wall, which is on the left. In that case the photographer can bounce the flash against that wall for a directional effect, as if light was coming in a window.
Bounce from an on-camera unit also can be combined with other photo flash sources. Some photographers carry flash on a stick and use that along with on-camera bounce. Such off-camera light maybe used 10% of the time. In case the ceilings are black, you can use it all the time.