When to Use TTL or Manual Flash

TTL means through the lens metering so when the subject has had enough light the flash cuts the power.  In this case exposure is changed using the +/- compensation on the controller, camera menu or on flash.

Manual flash just uses a % of available power, so full, half , quarter etc. The more power the brighter the image so if it’s too bright turn the power down,  decrease the ISO or use a smaller aperture. if it’s too dark turn the power up,  increase the ISO or use a larger aperture.

Manual flash is probably best in a studio, when the model and flash positions never change so this guarantees consistent results from frame to frame. This can make editing easier as the exposures should stay constant regardless of the reflectivity of the subject.

TTL tend to be better for fill flash outdoors or when the subject distance keeps changing such as on a wedding. In TTL mode the flash will output different power to suit the subject changing distance. A manual flashgun giving the correct exposure at 3m would over expose if you moved closer and under expose if you moved further away. TTL flashes would compensate for this change of distance automatically.

Finally, manual speedlights or studio lights need to have the camera in manual mode whereas TTL speedlights can be used in Manual or the Auto Modes. If you ever get confused by TTL speedlights try putting your camera on the Program mode and let the camera do the work for you.

You can find out more about flash photography on our Flash Photography Course, Portrait Photography Course, Studio Portrait Photography Course or Creative Lighting Course.

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