Question on light metering when using ST-E2

[Shadow]

I had always use the build in light metering as a guide to set the shutter speed and aperture. Not sure whether that the right way or not, but recently I was start taking tank photo with 3 flashes and I just realize it that light metering no longer work. It is not broken, it is just that without the flash the tank is dark.

I did couples of shot with fix aperture but different shutter speed. To my surprise all the photo exposure came out ok. Even when I do the extreme, 1/2000, I was expecting to be under expose but it is not. Does it mean that ST-E2 inform the 3 flashes what power need to output in order to get the right exposure?

[hwchoy]

yes, it is called E-TTL.

[benny]

Welcome to the world of automatic aquarium photography. You just find the fish and press the button!!

Cheers,

[CK Yeo]

to purposely under or overexpose a picture with flash, or so that reflective highlights don't burn out, you need to set the flash exposure compensation.

ck

[Shadow]

Thanks for all the comment

In summary please correct me if I'm wrong, ST-E2 will control/tell the 3 flashes to fire at certain amount of power. However, power is closely related to the distance between the flash and the object. Does it mean that I need to place all of the flashes approximately the same distance to the object? Otherwise one flash might fire at higher power than the other two.

Have not try out flash exposure compensation yet.

[hwchoy]

look at your ST-E2, it has this "ratio" thing. you can control two groups of speedlites (group A and B) and select the ratio of power between the two groups e.g. you want the side flash to fire at 1/4 of the flash on the top.

[Shadow]

o... Thanks for the tips, 1/4 of the top power, will try to do that.

[hwchoy]

eh 1/4 is just an example. you should experiment with various ratio depending on water height, substrate reflectance, shininess of the fish's various body parts, etc etc.

[trident]

Robert,
Actually I didn't set anything, set to same channel as the ST-E2.
Place the 3 flash in their position and fire away.
Works every time.