aperture/iso setting on flash when using it off-camera

[Stephan.]

When using a speedlite off-camera, do manual aperture and iso settings on the flash have any meaning at all?

[Curtis N]

Sure they do.

If the Speedlite is in manual mode, aperture and ISO will affect exposure (along with flash power setting, distance, modifiers and a few other things).

If the Speedlite is in E-TTL mode, the E-TTL system will attempt to account for the aperture and ISO settings as much as its power allows. Opening the aperture or raising the ISO will allow shooting at a greater distance from flash to subject. At a given distance, it will reduce the amount of power required, improve recycle time and increase battery life.

[Stephan.]

Thanks Curtis! I used to only use the power setting (being the most obvious) and the distance setting on my off-camera flash in manual.

So if I set the flash to ISO 100 and 1/4 power it will give more output than if I'd set it to ISO 1000 and 1/4 power, right?

[Curtis N]

Ok, back up a minute.
I think I misunderstood your question.

What flash unit are you using?

[Stephan.]

This question refers to a Nikon SB-28 DX.

[PacAce]

And what mode are you using the flash in? If in manual mode, none of the settings other than the power level is meaningful. If in auto mode, then the ISO and aperture set on the flash will make a difference in the exposure.

[Stephan.]

I'm using it in the manual (M) mode.
Isn't the zoom setting of any relevance?

[René Damkot]

zoom setting is, because more light goes to the subject, less to the surrounding erea;)
Flash puts out the same amount of light, but it's "concentrated more" so to speak.

ISO only alters the "distance scale" on the back of the flash.

[Stephan.]

Thanks René for the clarification.