I have done the photoresistor sync before and I've also used the commercial
versions (the cheap ones).  If RF is your thing, you can try Linx
Technologies (www.linxtechnologies.com). Their HP version will handle 50
Kbps and that should let you send a modest preamble/trigger sequence that
would significantly decrease the probability of false triggers and still
sync within 1/500th.  You could make many slaves and have each triggered
with a different preamble (switch selectable?) if you wanted to really
control the flash setup.  Also, you could dial in delay on the slave (flash
1/x seconds after trigger). Some pretty creative photos could probably
result from multiple flashes that were 1/100th apart.  I did one with an IR
beam breaker for a 'catch the water drop in mid splash' photo.  Just used
polaroid until I got the trigger timing right and then did the real one with
an open shutter in a black room.

You would need a hot oscillator or latency in processing would affect the
fastest sync timing.

In all, I would buy the commercial version unless you are doing this for
fun - which is my excuse for my projects..  A commercial kit would end up
cheaper (IMHO).  The Linx development kit is $299 - the modules are around
$60 for a rx/tx pair.

Dan

PS: I am not associated with Linx, but I've recommended them a couple of
times.  The reason is that I've settle on them as the modules for my current
project and I am satisfied with their performance.  I have not checked out
many of the other modules that are available - with one or two exceptions
which obviously wouldn't fit your needs.

----- Original Message -----
From: Douglas Burkett
To: PICLIST@MITVMA.MIT.EDU
Sent: Thursday, December 09, 1999 4:14 AM
Subject: RF Interface


I've read with interest the messages about RF and IR remote interfacing
projects, I'd like to put together a remote interface that triggers a camera
strobe based on trigger from the camera itself.  Commercial versions of this
in RF area are in the several hundred dollar range.  I've looked at the Ming
series and the decode time I believe would not lend itself to syncing with a
camera.  Most camera's (35mm) sync at around the 1/60th of second speed.  I
have shuttered lenses that sync at upto 1/500th of a second.  I have a 16F84
that I use with a direct connection to trigger via a cable a second strobe.
I'd like to rid myself of the cables.

Long winded I see, my question is,  are there available RF or IR modules
that would decode in time to sync at 1/500th?  I don't want to use unencoded
modules as false trigger would be fairly expensive waste of film.

Any ideas?

Thanks,
Doug