"Kevin Neilson" <kevin_neilson@removethistextcomcast.net

> wrote in message news:ici2b.253905$uu5.57673@sccrnsc04...

> I've read all I can about this, but am still confused. I'm trying to figure

> out if you can use the TTL feature of the Nikon SB-15 flash when it is

> off-camera and connected only with a PC cable.

No.

>Does the PC cable only tell

> the flash when to turn on, or does the pulse duration tell it when to turn

> off as well?

The former. The PC is shorted to fire the flash, but the electronics

and connections needed to shut it down in TTL mode are not there

(that's why there are all those pins on the flash's foot...).

> To get it to work with TTL, do I need that wicked expensive

> cable that connects to the hot shoe? (That cable is actually more expensive

> than the flash.)

About $25, used...

> If I use two flashes in TTL mode, do they both shut off at the same time?

Yes, if properly connected (you need an additional cable for this).

> Say I want to have a key flash and a rim flash, and I want the rim flash to

> be two stops below the key flash. How do I get the second (rim) flash to

> operate at reduced power? Is there any way to make it dimmer other than to

> modulate its distance from the subject?

You can also add sheets of paper, etc. to the face of the flash to

reduce the relative output of one of the flashes used TTL...

>I gather that more expensive

> flashes have some sort of switch that allows you to control the flash

> interval or something.

Some, in partnership with the camera, permit adjusting TTL fill

ratios, selecting rear-curtain synch, etc. Some cameras (F3, FE,

FE2) can be "cheated" into giving fill-ratios other than 1:1 using

adapters, cords, or adjustments in the way the film speed is

set and the meter is read...

--

David Ruether

d_ruether@hotmail.com

http://www.David-Ruether-Photography.com