In article <3vjfq4$b5l@hudson.lm.com>, joel@digalchemy.com says...
(some deleted)
>I just got an AS-7 to go with my F3 & SB-17 and was surprised to see
>an ISO speed dial on the AS-7. What does the SB-17 use this
>information for? What happens if I set a different speed on the body
>than the one on the AS-7 (in TTL mode)?

Learned this one from a Nikon rep. (Well, sometimes they know more
than I do about Nikon....). You have inadvertantly bought your way
into the first TTL fill-flash system made. The flash for the F3
senses the set ASA with a feeler in its foot which contacts a tab
on the ASA ring on the F3. When you use the AS-7 (or any of the
remote cords, which also have their own ASA ring), you can set a
different film speed for the flash. For example, if you use 100
ASA film, and want to have the TTL flash underexpose the ambient
setting by 1 1/3 stops, set 100 on the F3 ring, and 250 on the
shoe (or cord end) ring. Voila! TTL fill! Now, for the next trick:
Since turning on the flash shuts down the ambient-light meter,
and the shutter speed moves to the synch. speed, things get a
little awkward for metering ambient light - but wait, there is
a solution! Cover the center (of three) contacts on the camera
with a small piece of tape before putting on the shoe or remote
cord. You will lose the ready-light in the finder, but you will
keep the ambient meter and the complete range of shutter speeds.
(Do not use a speed above the synch. speed while the flash is on!)
Unfortunately (and this is why I no longer use this flash system),
the synch. speed is on the slow side, and the max. TTL film speed
is 400. Hope this helps.