Originally posted by mcgregni Hi,
No 1 is correct if using the Multi-brand firmware .... If using XTTL firmware the P-TTL Passthrough flash must be controlled with the V6IIs interface.
No 2 is not quite correct ..... The V6 II uses the camera metering system to determine power output levels for the RF60x slaves in TTL mode.... No PTTL flash is required.(Perhaps that's what you meant anyway?)
3 is right. .... The pre-flashes are used by the camera metering system to determine the flash output , in the same way as multiple P-TTL flashes. The only difference is the Radio communications instead of optical.
4 is correct .
I'm glad my post stimulated the questions! ....
Edit .... Just thinking more about it, I suppose really it is the camera metering system that calculates the required flash EV, and the V6II that translates that into power output instructions for the slave flashes. It's worth noting that (just like for the Pentax optical wireless system), it is a global (combined total of all slaves) flash EV that is determined .... This is then split equally between the flashes (so a flash further away would output more light to balance the output from a closer flash). The compensation settings are an offset to this applied locally at each flash
Again, it's all the same as for the optical wireless system, just that the Radio remote control gives easier direct control over things.
One final thought about your point 3 ... There are two district types of optical "signals" emitted during pre-flashes ....metering illuminations and communication signals. The metering illuminations are read through the lens as brightness by the metering sensors. The communication signals are coded messages sent to the slave flashes to control them. In the case of RF60x flashes, only the first metering type of pre-flash applies .... There are no optical communication signals as this functioning is performed via radio waves instead.
Thanks. My extended response was just eaten by the site somehow, so it will take a while to reconstruct.
---------- Post added 13th Aug 2018 at 20:39 ----------
Originally posted by mcgregni Hi, ... I'm glad my post stimulated the questions! ....
Thank you. I think it will be helpful if I excavate the rabbit hole a smidgen further, if you are game. I have taken the liberty of rearranging your text.
Originally posted by mcgregni No 1 is correct if using the Multi-brand firmware .... If using XTTL firmware the P-TTL Passthrough flash must be controlled with the V6IIs interface.
I would expect to be using A06 and PEN.A.001 firmwares. These are the XTTL relevant ones?
By "controlled" do you mean merely that the V6II must be directed via its user interface to allow the pass-through, or that the V6II meddles with the data being passed through?
Originally posted by mcgregni No 2 is not quite correct ..... The V6 II uses the camera metering system to determine power output levels for the RF60x slaves in TTL mode.... No PTTL flash is required.(Perhaps that's what you meant anyway?)
I fear that I meant something entirely different expecting multiple P-TTL pre-flashes, but which upon reflection could imply a control process too Byzentine in operation to possibly work. So let me ask a simplified question: With one Pentax P-TTL flash mounted on the V6II operating in passthrough mode, and one or more R60X under RF control of the V6II, how many flash heads generate a pre-flash when the camera thinks it is in P-TTL mode and all the flashes think that they are in P-TTL mode?
Originally posted by mcgregni 3 is right. .... The pre-flashes are used by the camera metering system to determine the flash output, in the same way as multiple P-TTL flashes. The only difference is the Radio communications instead of optical.
One final thought about your point 3 ... There are two district types of optical "signals" emitted during pre-flashes ....metering illuminations and communication signals. The metering illuminations are read through the lens as brightness by the metering sensors. The communication signals are coded messages sent to the slave flashes to control them. In the case of RF60x flashes, only the first metering type of pre-flash applies .... There are no optical communication signals as this functioning is performed via radio waves instead.
I think the answer to the additional No. 2 question applies here also.
Originally posted by mcgregni 4 is correct.
But let me ask another simplified question: With no Pentax P-TTL flash mounted on the V6II, but with one or more R60X being under control of the V6II, how many flash heads generate a pre-flash when the camera thinks it is in P-TTL mode and the R60X flashes think that they are in P-TTL mode?
Originally posted by mcgregni Edit .... Just thinking more about it, I suppose really it is the camera metering system that calculates the required flash EV, and the V6II that translates that into power output instructions for the slave flashes. It's worth noting that (just like for the Pentax optical wireless system), it is a global (combined total of all slaves) flash EV that is determined .... This is then split equally between the flashes (so a flash further away would output more light to balance the output from a closer flash). The compensation settings are an offset to this applied locally at each flash
Again, it's all the same as for the optical wireless system, just that the Radio remote control gives easier direct control over things.
Depending on the new answers, it would seem that one can operate with one V6II and one or more off camera (and connected by RF only) R60X flashes, avoiding the need for an AF-540FGZ, even when only a single P-TTL flash is needed.