Hey Gang,

 Matthew Paquin has done some shooting around AHA / Character Party /
General Awesome, he's looking for a solution to a problem he's run
into:

"I have a Canon camera with a TTL hotshoe (TTL provides more data then
your standard "fire/don't fire" hotshoe, it also has 4 more pins). I'm
using a cord that is TTL compatible to communicate with a TTL flash
off of the camera. The cord also has an extra hotshoe built in that
sends a non-TTL signal (only 2 pins, instead of 6) to a radio
transmitter that I have. In theory this should allow me to both fire
the TTL flash (with all it's special goodness) and fire the radio
transmitter. The camera and flash work perfectly, but as soon as I put
the transmitter on to the non-ttl hotshoe on the cord it interrupts
the TTL signal to the flash. Essentially it's turning what should be
one TTL connection and 1 non-ttl connection into 2 non-ttl
connections. (I'm sorry if I didn't explain that well). It appears as
if the radio transmitter is completing the circuit and messing with
the flash. Placing a normal flash or other gear on this non-ttl
hotshoe doesn't interfere in this way, only the radio transmitter.
I've tried multiple cords, flashes, and transmitters with the same
results.

I'm looking for somebody that can either modify the transmitter, put
something in between it and the cord, or modify the flash to work in
the fashion I described (TTL on the flash, non-ttl to the radio
transmitter).

I'd be willing to bring the whole mess to AHA (or wherever) and I'd be
looking to pay up to around $100."

and a follow up:

'Also I talked to some industry flash experts and they explained to me
what would need to be done. Apparently they don't do it because it's
to expensive for the limited amount of people that would want it.
Here's what he sent me:

"To make this work correctly, you have to analyze and filter the
digital signal coming from the camera that is superimposed on the
firing pin (center contact). This needs to be done using a
microcontroller, so that when the the digital signal is sent
indicating that the next signal is the firing signal, your interface
device will then accept the trigger signal (ignoring the control
signal immediately preceeding) and then the output from your interface
device will then fire the transmitter."'

Thoughts? : )  I'm forwarding him the google groups link for this so
he can follow along.

Thanks!

 - Josh W.

IMG_7207.jpg 633K Download

I'd give it a shot, but without a nice logic analyzer and knowledge of the
encoding/transmission scheme being used, I can't guarantee that I'll be
able to make it work.

-Eva

--khd