I have an entry level Canon camera with a built-in flash.
When I try to photograph people at night the camera fires some pre-flashes to help with focus. While I do understand its necessity, some of my subjects are confused by these flashes thinking that I actually take the photo.
I bought an external flash and one of the reasons for buying it was that I read on the specs that it has a red light that can help with focus.
I put it on the camera, and while shooting the flash still fired pre-flashes! I finally found a setting in the flash the enables the red lamp in order to focus.
But I am curious why this is not the default setting? The pre-flashes drain the battery and confuse my subjects. The red light is much more inconspicuous and at least so far it has always locked on focus.
So do I miss something if I enable this setting permanently so that only the red light is used for focus assist?
As an added advantage the red light will always work even if the flash head is turned to the ceiling or to the wall.
Camera is 700d and the Flash is 430IIIEx
The setting I am talking about is described in the manual Personal setting F05 - AF-assist beam emission method
Setting 0 - default -Small series of flashes fired by flash
Setting 1 - Infrared Infrared AF-assist beam aiming at the center AF point is emited
My question is essentially why setting 0 is the default and not 1? Also what do I miss if I select permanently setting 1