Interesting observation about 580 exII power

I was shooting a party in a an extremely dark venue last night- The place was themed as a coal mine, but it was actually darker. To make matters worse, the DJ was in love with his smoke machine.... which really made thing hard on auto-focus and flash.

Here's what I thought was interesting- My flash was on-camera. I had hoped to bounce it off something, but that plan didn't really work out with the dark walls and ceiling. When it fired, I got far more reflection from the smoke than I did light on the subject. Under the circumstances, I wanted to try to get close to the ambient exposure (1/100, 2.8, iso 25600... dark...) and give things just a touch of fill. In M, I set the flash to 1/128- its minimum setting. There was still way too much flash in the exposure for my liking. I switched to ETTL, with FEC of -3, and things were right where I wanted.

Can ETTL with FEC create a lesser burst of light than minimum power on M? It must.... I was surprised to see that.

Any other explanations?

sfinkernagel wrote in post #14061283
In M, I set the flash to 1/128- its minimum setting. There was still way too much flash in the exposure for my liking. I switched to ETTL, with FEC of -3, and things were right where I wanted.

Can ETTL with FEC create a lesser burst of light than minimum power on M?

Yes, about 1/512th power.

Good to know.... But I wish I had control of that in the M mode...

The only way I have found to manually control my speedlites lower than 1/128 is using a radiopopper JrX Studio with RP Cube. It goes REALLY REALLY low with the RP.

picturecrazy wrote in post #14065443
The only way I have found to manually control my speedlites lower than 1/128 is using a radiopopper JrX Studio with RP Cube. It goes REALLY REALLY low with the RP.

Thanks- might be worth looking into...

You can always diffuse the light to reduce its effective power. There are various ways to do that - translucent plastic cover, bounce card, small softbox, etc. Even pulling out the wide angle diffuser will help some.

HSS should drop your power down by at least 2 stops, but you gotta get there. What was your SS and ISO when you were shooting?

sfinkernagel wrote in post #14061283
Under the circumstances, I wanted to try to get close to the ambient exposure (1/100, 2.8, iso 25600... dark...) and give things just a touch of fill.

windpig wrote in post #14066197
HSS should drop your power down by at least 2 stops, but you gotta get there. What was your SS and ISO when you were shooting?

I wanted to include the ambient lighting in the shots- they place had all kinds of colored, laser/mirrorball lights.... was kind of a cool atmosphere if I hadn't been taking photos. That's a good thought though- I'll remember it for next time.

Curtis N wrote in post #14066099
You can always diffuse the light to reduce its effective power. There are various ways to do that - translucent plastic cover, bounce card, small softbox, etc. Even pulling out the wide angle diffuser will help some.

Good thoughts- noted.

Thanks!