Fill Flash Challenged?

Sailor Blue wrote:

The type of photos you are trying to take are really two photos in one.

One photo is of the background, which is an available light photo. This is the exposure you get when you half press the shutter button. In Av mode the camera will adjust the shutter speed to give you the correct background exposure. If you have ISO set to Automatic then it may also be adjusted.

The second photo is of the subject that is lit with light from the flash. This exposure is set in E-TTL II mode by the camera measuring the light reflected from a pre-flash. The camera then tells the flash to use the amount of flash power that it thinks is the correct amount.

In AV mode the way you control the two exposures is by using Exposure Compensation for the ambient light background exposure and the Flash Exposure Compensation for the flash exposure.

I suggest you buy a copy of Syl Arena's excellent tutorial book, "Speedliter's Handbook". While waiting for it to arrive watch these free B&H TV video tutorials by Syl.

Syl Arena - Speedliter's Handbook: Learning to Craft Light with Canon Speedlites (9780321711052)

Syl Arena - B&H - Getting The Most Out Of Canon Speedlites

Syl Arena - B&H - Canon Speedliting with Multiple Flashes

Frankly you are much better off using your flash off-camera flash in manual power control mode. If you watch this free tutorial from Sekonic you will see some of the ways you can adjust the power of the off-camera flash to control the ratio between the ambient lit background and the amount of fill light on the subject. It also shows how using the flash off-camera give you great control of the ratio of highlights to shadows on the model's face, and having both highlights and shadows is what gives an image of a face a 3D appearance.

Sekonic - Control the Light and Improve Your Photography: Part 2 — Better Environmental Portraiture

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Living and loving it in Bangkok, Thailand. Canon 7D - See the gear list for the rest.