ISO usage on the flash and camera

Stephen71

Something i have never considered when learning flash is the adujustment of iso on a sb900 flash unit.
I bring this small topic up when this morning i was reading another book on the subject of flash and the photographer had mentioned that while taking a photo of an animal in the lake , he had raised the iso on the ( camera ) from 200 to 800 iso
Then adjusted the iso on the sb900 to 800 iso, this is something i never considered and im wondering why .
Now i totaly get how to use off camera flash. Four things to change exposure Aperture , iso , distance and power.
The iso part this would be on camera as this would extend flash range but ive never heard of changing this on the flash unit alone.
Is there any reason for changing the iso on the flash unit alone ? I have never read Neil or any one else doing this.
The only reason i can think of is to match the same settings as the camera setttings ie a standard pocket wizard that does nt fully give all the info to the flash
Regards
Steve

Neil vN

Setting the ISO on the flash makes no difference at all. It is superfluous. 

The only reason you would, is so that the distance scale on the flash makes sense. 

But if you are shooting manual off-camera flash, as metered with a light meter, then the ISO setting on your flash is of no consequence at all. 

Stephen71

Im so glad you said that. , talk about a spanner in the works,, after all that i have studied this crops up .
With the distance scale on the flash this would makes sence as this is what the subject was about in and around.
I get what you said neil. So thank u