Technical Question about flash (SB-600)

[cumi]

I am considering to buy an SB-600. There are some points what I don't really understand how it works, like:

How do I get a correct exposure (D70s), when the flash not directed to the subject, but is bounced, bounced on ceiling or wall, or used with diffusor?

The built-in flash does (some) test-flashes to measure the exposure and flashes for the photo correctly (for example like in P-mode) automatically. I can even do flash exposure corrections... How does this works, when I want to use indirect light? Does the SB-600 also does some test-flashes?

And, how does this change, when using SB-600 off-camera (nikon wireless system), so no direct (electronic) communicaton between flash and camera. How does then the camera knows what F-stop has to be for the correct (flash-) exposure?

Do I have to do in both of these cases manually and hoping that the exposure will be correct?

I tried an (old) SB-28 with my D70s of course only in manual mode (because D70s needs iTTL and can not work in "old" TTL mode). All the photos were hopelessly over-exposed, regardless if I directed it to subject or bounced it on ceiling... So with SB-28, I had to calculate everything and set manually. When not directed to subject, I could only guess and try how to set the camera...

 

[The_Traveler]

Not to worry, it works.
The camera reads the exposure TTL (through the lens) and compensates.

 

[cumi]

Not to worry, it works.
The camera reads the exposure TTL (through the lens) and compensates.

This means that the external flash does test-flashes before the real one?

 

[fmw]

This means that the external flash does test-flashes before the real one?

No the metering system in camera controls the duration of the flash in order to get the right exposure. It happens during the exposure, not before. Take care.