Flash exposure / ambient compensation

[Rick448]

Hi,

After trying to learn about using my flash Better I am going to try under exposing the ambient light whilst using the flash to light the main subject. I understand I can do this by taking an initial meter reading and then using the manual setting to under expose by a couple stops or so and then use the flash either TTL or manual.

My question is, can I use my exposure compensation from the camera set to minus 2 rather than going manual, and then use the flash TTL and get the same result, or will the flash aim to light at the minus 2 stop setting. If this is the case it I set + 2 stops on the flash will I get the desired result?

I know i will probably need to go manual to get the shots I really want at some point but I am just wondering if I have a grasp of this.

I have a 70D and 5D3 along with an ST E3 RT and a Canon 600EX RT and 2 YN600EX RT's.

Thanks.

[ChrisLumix]

I would think your discussion is about using flash in combination with other light, where you have a distinct separate foreground and background?

 

You should therefore expose in the camera (the EV control) for how you want the background to appear; if you want the background dark then set the EV to a minus figure.

 

You should use the flash controls to light the foreground (main subject) which is what the flash will expose for. You can go anywhere from 'fill flash' (underexposed) up to say +2 or +3 stops to force the flash to output more light.

 

Remember that you have a 'whole scene' and a typical flash will only cover the foreground. Therefore use the flash controls for that. The background you set using the camera's controls, including EV if desired.

 

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If you are shooting only a main subject against a plain background - e.g. a studio shot - then flash and / or studio lights are everything and you can forget everything else.

 

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Generally though, you want to avoid under-exposing ambient lighting and relying predominantly on flash : unless you are using some kind of diffuser you will find flashlight is harsher. Better to expose using ambient light then add flash as a 'fill' if necessary. That's been my experience anyway.