More power from cord or wireless?

I wonder if one of you flash gurus can tell me the answer to this. I recently used my 580EX through a shoot-through umbrella (on a stand) using Yongnuo flash triggers - which work perfectly, by the way.

At a distance of about 8 feet or so, I have to use f/4 at ISO 100, which doesn't too much use to me. My question is, would I get more power if I used an off-camera flash cord, so that I could make use of the flash unit's TTL facility? This might seem and odd question but the reason I'm asking is that I believe that the flash (in auto mode) alters the exposure not by altering the light output, but by altering the duration of the flash. The ancillary question, therefore, is - when in manual mode, is the flash firing for its maximum duration? If it is, then I've got the answer to the question.

If it isn't at maximum duration in manual mode, that leads me to hope that, by using the flash in EETL mode (with an off-camera flash cord) I can coax more power from the unit.

I hope this hasn't been too convoluted but I'd be grateful for any help or opinions.

I don't entirely understand. The way you trigger a flash is irrelevant, just put it on manual full power and it'll give you as much light as it can.

E-TTL won't get you more light than full power in manual mode.

tim wrote in post #8677686
I don't entirely understand. The way you trigger a flash is irrelevant, just put it on manual full power and it'll give you as much light as it can.

I know that the way it's triggered won't alter the power - I was asking really about the difference in power between manual and ETTL. But thank you for your response.

Curtis N wrote in post #8677694
E-TTL won't get you more light than full power in manual mode.

That's exactly what I wanted to know - thanks Curtis. Tell me, does f/4 at 8ft (ISO 100) through a shoot-through umbrella seem reasonable to you?

Sounds about right.

Now do yourself a favor. Crank up the ISO to 400 and drop the flash power down to 1/4. You'll have nearly instant recycling, your flash won't overheat and your batteries will last longer.

Mowing the light closer will help, too. Get it 4 feet away and it will give you 2 stops of light.

Curtis N wrote in post #8677694
E-TTL won't get you more light than full power in manual mode.

Now that I knew , but what about the reverse is it possible that in ETTL Mode I can get less than 1/64 in Manual , seems like a silly question but sometimes shooting Macro close up this may be helpful .


David

Curtis N wrote in post #8677875
Sounds about right.

Now do yourself a favor. Crank up the ISO to 400 and drop the flash power down to 1/4. You'll have nearly instant recycling, your flash won't overheat and your batteries will last longer.

Its worth reading the above twice.

Roy Mathers wrote in post #8677773
I know that the way it's triggered won't alter the power - I was asking really about the difference in power between manual and ETTL. But thank you for your response.

You can't use ETTL with your radio triggers, and a flash can't put out more than you get on full power manual.

The ISO thing is important. I almost never shoot ISO100, often ISO800 at wedding receptions where i'm using speedlites to light the room.

Curtis N wrote in post #8677875
Sounds about right.

Now do yourself a favor. Crank up the ISO to 400 and drop the flash power down to 1/4. You'll have nearly instant recycling, your flash won't overheat and your batteries will last longer.

Mowing the light closer will help, too. Get it 4 feet away and it will give you 2 stops of light.

That's good advice Curtis - I'll take it! Thanks.

tim wrote in post #8677917
You can't use ETTL with your radio triggers, and a flash can't put out more than you get on full power manual.

The ISO thing is important. I almost never shoot ISO100, often ISO800 at wedding receptions where i'm using speedlites to light the room.

I know that Tim. If you re-read my original post you will see that my alternative was to use an off-camera flash cord - which will allow me to use ETTL.

Stickman wrote in post #8677886
Its worth reading the above twice.

I have!

dpds68 wrote in post #8677881
is it possible that in ETTL Mode I can get less than 1/64 in Manual

Evidence seems to indicate the 580EX can output less than 1/128 power in E-TTL mode.

I don't think i'm with it today, sorry. Your question's been answered anyway

Curtis N wrote in post #8677982
Evidence seems to indicate the 580EX can output less than 1/128 power in E-TTL mode.

Thank you much .