Originally posted by Frogdog Can you clarify on the point you made here? : " Where things get strange is if one attempts to use the pass-through hot shoe on the Adapter F at the same time. The contacts are in common between the two and compatibility with the O-GPS and a flash is unlikely."
This is my first experience using the adapter F and I was under the impression that it passes full functionality through the pins - somewhere in the K30 manual I thought I remember reading general flash functionality was possible without notes defining any restrictions while using the O-GPS - I kind of ran with it from there. I honestly may have read that within the K70 manual when I was researching which model to start out with.
Glad to be of service!
In regards to the Hot-Shoe Adapter F, the 5P sync cord F, and the Off-Camera Shoe Adapter F when used together; the shoe contacts for both adapters are wired in parallel to the foot contacts of the Hot-Shoe Adapter F. While both are true pass-through, the circuits are not isolated. The lack of isolation has implications, the nature of which devices share the circuits.
Example #1 | Center (sync) contact
There is a common side-effect when using two flashes having different trigger voltage (example: 6V and 4V), one on the camera adapter and the other on the off-camera adapter. When sync is fired, it is possible only one of the two flashes will fire due to the circuit voltage only dropping low enough to trigger the higher voltage unit while the circuit was closed for sync.
Example #2 | Dedicated "ready" contact
Another problem might be two Pentax-dedicated flash where "ready" might go "high" for the circuit and "ready" being shown in the viewfinder with only one flash actually recharged. This is an issue only when using cameras that support the analog dedication/control protocol such as the Pentax LX film camera.
Example #3 | Digital (data) contact
The potential problem here is one of cross-talk or mixed messages across the digital/data contact. The 5P cables and connectors date back to the digital dedication/TTL protocol where the bulk of the logic was on the camera and communication to the digital contact could be shared and be equally relevant for a long daisy chain of hard-wired off-camera flash TTL flash. That changed with P-TTL where most of the logic is borne by the flash with a fair amount of exchange between flash and camera. If more than one flash is used per control circuit (the built-in flash has its own), the intent is that communication be done through optical wireless with one master. Moving from flash to the O-GPS, that unit is in intimate continuous communication to control the image sensor position. I don't own an O-GPS to test with, but unless there is provision to ignore or turn off the source of other signals, potential for interference definitely exists. I would use strong caution if attempting mixed O-GPS and P-TTL communication on the same digital contact circuit (i.e. both on the same 5P cable).
I hope you share this project and its outcome. Something tells me you have something interesting in mind.
Stee