Success with on-camera flash often means going for a natural look, enhancing what ambient light is there or at the very least creating a natural-looking result. Fortunately, the latest digital SLRs have a very high ISO performance, which makes it easier to use existing light while minimizing the evidence of flash. Using high ISO and dragging the shutter a bit in combination you can prevent that flash fallout from becoming very evident. With the 1DS and 5D it is possible to go through the entire range up to 3200 ISO, and because of the high resolution you can really control noise, giving you a lot more flexibility by using more ambient light in the exposure.”

Actually, flash intensity is not an essential factor anymore, because in modern sophisticated cameras, having super-high ISOs and fast lenses, almost any amount of flash provides some sort of lighting. In fact, with all these facilities you generally find your on-camera flash to be too strong at full power. It helps shooting in Raw also. It gives you latitude without having to worry about color temperature, especially when you are switching between flash on and flash off between shots and there is no time to fuss with WB settings. When you drag the shutter a lot in combination with flash, sometimes you will get different color temps between the subject and the background, and Raw makes it easier to deal with that and color cast in post-production.”

It is also easier to deal with the noise that tends to result from high ISO when you are shooting in Raw. But different converters handle noise better than others. Conversion with Canon's DPP, though color is good. is not always best for high ISO images. In those cases Photoshop CS's Camera Raw is a better choice. And, if you are really trying to clean up a noisy image, use a Noise Ninja on a converted TIFF or directly through Bibble.

If you bounce you will not have a lot of problems with flash shadows and the only shadows that you may find objectionable are those side shadows that appear when you turn the camera for a vertical shot and the flash is bouncing just to the right or left of the lens axis. This can be rectified completely by adjusting flash head. Diffusers are also widely used to minimize shadows, but not everyone buys into their effectiveness, because third party diffusers might complicate things further. However, wedding photographers occasionally use the wide-angle diffuser on the flash itself or the white card built into the flash head. And there is no substitute for fast lenses, which bring in more ambient light, allowing the photographer more of a balance between that and the flash.