What is TTL flash?

TTL is short for through the lens. TTL is a mode, that a flash can operate in. When the flash in in TTL mode, the flash will fire a pre-flash and the flash power will then be automatically set in a fraction of a second, based on a light metering through the lens by the camera.

When is TTL flash used?

If the the eyes, face or other important features of the subject is unevenly lit and the subject is too dark with high contrast, then TTL flash can lift the shadows and light the subject to match the natural ambient light in the background. If the sun is warm and setting, then an orange gel or filter can make the flash warm as well.

Find a good spot for portrait photography.

Consider a place with some trees or some shade. Face should be in neutral even light. Not in harsh uneven light. This will make it possible to control the light.

Dial in the exposure on the camera.

Set camera to manual mode. Set light metering to an averaging mode. Dial in the exposure to 1/160-200s, f/1.2-5.6 and ISO 100-400. Keep ISO as low as possible to avoid noise. Make sure, that the flash is turned off, and take a test image and review the image and the histogram. A correct exposure will not have peaks up against the left side nor the right side. Adjust as necessary.

Dial in the exposure on the flash.

If it is sunset and the light is yellow, then use an orange gel or filter on the flash. This will make the flash light become warmer and the image will become more natural. There are usually a half tone and a full tone.

If the flash can not be bounced off a light wall, then point it directly at the subject.

Set flash to TTL mode.

If direct flash is used, then adjust the shutter, so the meter is zero or slight over-exposed. The flash will become more soft. The reason is, that a dark background wil make the flash too bright. Is it better to just use FEC and reduce flash power?

Use a flash transmitter and a softbox to make the light source bigger and softer. Place the softbox as close as possible to make the light as big as possible for softer light. Use a diffuser and un umbrella to make the light source bigger and software.

Adjust flash exposure compensation (FEC) as necessary to make the light soft and natural. Remember, that the camera will by default measure the brightness of the average scene and light it towards grey. Dark scenes will become too bright. Bright scenes will become too dark.


More about TTL flash portrait photography.