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01-02-2010, 01:31 PM   #1
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P-TTL off Camera

Hello,

I've been looking around and can't seem to find an answer to this question. The Pentax hot shoe adapter F seems to allow you to connect two P-TTL flashes; one on the hotshoe mount, the other at the end of an attached cord. Is this correct? Will both be able to communicate with the camera simultaneously? Any special advantages?

I just got a Metz 48, and am debating whether or not to sell my Promaster 7200; it has no manual controls, and as such is useless as an off camera flash as I understand it. If there's a way to get something cool from wiring two flashes to my camera, I'd love to try it though!

01-02-2010, 02:30 PM   #2
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You can't use a flash on the camera as there isn't a lock on the hot shoe mount. The only flash you can use on the camera and still use a remote flash via a 5p cord is a Pentax 540FGZ. The 540FGZ has a 5p port built in for the flash cable to allow for this.

You can however, stack two hot shoe modules on the camera and use both flashes via the remote cords. This is almost the same, just requires more hardware.

Thank you
Russell
01-02-2010, 10:31 PM   #3
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Do I need to re-plan?

Thanks Russel.

So can I not mount a flash because it'll fall off? Or is this an electrical issue?

I'm using the adapter in an attempt to begin hacking together a custom wireless trigger setup. I don't need to be able to move things around, I just want to intercept the serial communication between the flash and the camera so I can begin to figure out how to manage the communication wirelessly.

I just plan to place the flash on the Hot Shoe Adapter F, then slip wires into the connector to hook up a micro controller. Is there something wrong with this plan?

I'd rather figure out the physical side of things after I have the electrical side of things working.

Looking at Pentax's website more carefully, it's missing a hole where the locking pin goes. The Promaster Doesn't have the little locking pin, the Metz does. So I figure the Metz will be harder to fool, I may need the Promaster after all.


Thanks again for your help!
01-03-2010, 12:20 AM   #4
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Quick update: I went ahead and tested my Metz 48 without screwing down the locking ring. (To simulate using the hot shoe adapter)
Anyway, all the features appear to work perfectly, so I've got my fingers crossed and will probably order a hotshoe adapter tomorrow.
Fingers crossed for diy RF p-ttl!

01-03-2010, 01:57 AM   #5
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QuoteOriginally posted by m88k Quote
So can I not mount a flash because it'll fall off?
That is the issue, yes. The flash and hot shoe adapter might fall off of the camera. You can of coarse use it this way at your own risk, I just didn't want you spending your money and then having a "Aw shucks" moment.

Thank you
Russell

Last edited by Russell-Evans; 01-03-2010 at 03:13 AM.
01-03-2010, 02:42 AM   #6
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if you manage to set such a wireless trigger, let us know. that would be a premiere in Pentax flash history
01-03-2010, 07:01 AM   #7
clm
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Yes you can

QuoteOriginally posted by m88k Quote
Hello,

I've been looking around and can't seem to find an answer to this question. The Pentax hot shoe adapter F seems to allow you to connect two P-TTL flashes; one on the hotshoe mount, the other at the end of an attached cord. Is this correct? Will both be able to communicate with the camera simultaneously? Any special advantages?

I just got a Metz 48, and am debating whether or not to sell my Promaster 7200; it has no manual controls, and as such is useless as an off camera flash as I understand it. If there's a way to get something cool from wiring two flashes to my camera, I'd love to try it though!
Yes, this will work if you have two P-TTL flashes. Pentax off-camera flash has worked this way with TTL since the SF series cameras came out.

http://kmp.bdimitrov.de/technology/offCameraFlash.html

"might fall off" isn't the same as "it won't work."

Last edited by clm; 01-03-2010 at 07:03 AM. Reason: added link
01-03-2010, 03:16 PM   #8
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Good deal! I appreciate your concern for my flashes Russel, but this setup likely won't leave my desk once it's wired up.

Don't hold your breath on the triggers; I have a hard enough time keeping up with classes! That and I have almost zero experience in digital electronics. :-P But I'll be buzzing away for the next couple months trying to keep ordered notes on what works and what doesn't, see what I can figure out.

I've got a couple cool photos I'd like to try, but the equipment to take them doesn't exist... And now you all know I'm crazy.

01-04-2010, 02:41 PM   #9
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Hello m88k, I think we are after the same things: the functions, voltage level, serial protocol etc. of the Pentax hot-shoe. I may say that I have a lot of experience in digital electronics and microcontrollers, so we could share knowledge and ideas.

Could someone out there tell us where we can find all necessary details to take advantage of the Pentax hot-shoe?

Thanks in advance.
01-04-2010, 05:16 PM   #10
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That's what I'm figuring out!

Hi Jean, Hot Shoe Adapter F should make it simple to intercept communications between the flash and camera.

I'll have to take voltage readings before hooking it up, but from what I've found pentax has been keeping all flash pins bellow 6v since the late 80's.

I've also found this site, which, along with detailed information on the entire Pentax flash system. Next step is hooking up and seeing what can be discerned.

I know hot shoes are customized by brand; does anyone know if the f5p connector is borrowed from some other field? Could they be bought from Mouser, Digikey or the like? I'd rather not buy and cut up expensive cables!

Any thoughts on the best way to monitor and decode serial communication? Can it be done directly through a PC serial port, or do I need to use some form of external micro-controller like the Arduino or Mbed?

I'm also not sure how to determine which unit is talking. It's probably best to set up a dedicated thread or separate website for collecting this information.
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