TTL flash exposures

With TTL, the camera does the hard work for you, but it may need a helping hand

When your flash unit is set to TTL (Through The Lens) mode, all you need to do is make sure that your shutter speed is no faster than the flash sync speed, and ensure that the flash unit is close enough to the subject (many flashguns will indicate the reach of the flash on their displays).

TTL is fast and smart, but not consistent. If the backdrop changes or you shoot from a different position, then the camera may decide to adjust the TTL flash exposure. It can also be affected by reflective parts of a scene, such as windows or mirrors, and particularly pale or dark subjects – just as a standard exposure without flash can be. This means that you may end up with some shots where the flash exposure is not bright enough and others where it’s too ‘hot’.

Fortunately, you can override the TTL flash exposure using Flash Exposure Compensation. This can usually be applied in increments of 1/3 stop, on the camera or on a flashgun. Use positive compensation to make the flash exposure brighter, and negative compensation to make it less bright.

Splash exposure TTL is a good choice when your subject is on the move and you don’t have time to make manual adjustments.

Beam me up (or down) Use Flash Exposure Compensation to increase or decrease the brightness of the TTL flash exposure.