[TonyW]

I purchased a pair of Cactus V6 II to gain the ability of HSS with my 645.

HSS works great at all speeds up to the 1/4000 max with one unit on camera set to TX all is well and the camera recognised, similarly with the other mounted to the flash set to RX the unit is recognised (Yongnuo 568 EX Nikon).

I do not as yet own any Pentax PTTL compatible flash units all being Nikon equivalent including the Nikon SB600 and a pair of Yongnuo 568 EX (Nikon compatible).

So far I have a couple of questions on compatibility:

1. I would like to be able to use one of my flash units for HSS mounted directly to the Cactus in turn being mounted to the camera. So far I have not had any success with synching above 1/125 sec. Any suggestions what am I missing?

2. I suspect the answer is no to this but again I could be missing a simple setting. I know that the Pentax PTTL and Nikon iTTL systems quite different and not directly compatible. However Cactus V6II seemed to be touted as cross brand TTL unit and I had thought that this may mean some magic fix to compatibility allowing the TTL aspects to work between different systems. I am far from unhappy setting aperture manually but automated system may on occassion prove useful. So apart from investing in Pentax flash or compatible is there any setting to allow TTL with these different systems?

[mcgregni]

Hello. TTL with Cactus and Pentax will only work with P-TTL (Pentax dedicated system) flashes, or with Cactus RF60/x flashes. For us there is not the "cross brand" TTL available.

HSS with the V6II radio system needs to be via radio communication, not through the flash hotshoe. Maybe try a flash bracket with the system on short range for on camera working.

A great advantage with Cactus RF60/x flashes is there is no need for a Receiving (Rx) V6II, as this is built in to the flash. Also, as I said earlier, with the correct X-TTL firmware they come with TTL ability, and HSS, when triggered by a V6II Tx.

[TonyW]

Thank you mcgregni.

No big deal that there is no "cross brand" TTL as I am usually more than happy to work in full manual. Still it would be nice to have the option so I may look into the Cactus RF60 if the need arises.

Flash bracket I will try for HSS.

Something else I discovered while playing this evening is that the zoom features does not function at all with the Yongnuo (not tried the Nikon SB600 yet) although the power output adjustment works just fine - not sure yet if this is lack of compatibility of the unit or other.

I assume that all these units work in both P-TTL and TTL? The reason is that from past experience with pre flash my family are the worlds best blinkers and really adept at anticipating the flash trigger leading to quite a few closed eye shots, so I prefer to cut out the pre flash

And thanks for the flash guide you produced I know how much work and time this must have taken so much appreciated

[mcgregni]

You're welcome! I'm pleased you found it interesting. The remote flash head zoom of course should work, but its all quite a big ask to expect full compatibility between electronic devices made by three totally independent companies, and without any specific co-operation between them. As we've been seeing on an adjacent thread here, we cannot expect everything to be seamless when there are variables between third party flashes and the way they implement the P-TTL / TTL protocol.


There have been recent reports of the Yongnuo P-TTL model not remote zooming either, as well as with some Metz models, and also reports that the camera format seems to have an effect on this (eg needing to set the 'crop' mode on the K1 to get zooming going). Perhaps this is relevant to your 645 also? The Pentax flashes are designed to accommodate correct display of zoom positions for all formats (35mm, aps-c and 645), whereas the third party models probably are not. However there was a firmware update for the Yongnuo P-TTL model that I think fixed this? It might be over-optimistic however to expect the same result for a Nikon version though. But worth updating the flash if its possible.

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Last edited by mcgregni; 12-29-2017 at 06:55 PM.

[Class A]

I would like to be able to use one of my flash units for HSS mounted directly to the Cactus in turn being mounted to the camera.

Do you want to use the flash on-camera, with the Cactus V6IIsandwiched between camera and flash?

In that case, have you configured the camera system to be "PENTAX" (or left it on auto-detect) and configured the flash system to "NIKON"? You may also want to manually choose the flash model you are mounting on the V6II. I'm unsure whether this may support HSS. It may very well not work, but I guess it is worth a try.

However Cactus V6II seemed to be touted as cross brand TTL unit and I had thought that this may mean some magic fix to compatibility allowing the TTL aspects to work between different systems.

There are two different kinds of firmware for the V6II.

The "multi-brand" variant supports cross-brand power control and HSS.

Only the other "X-TTL" variant supports cross-brand TTL support. Unfortunately, however, the Pentax version of the X-TTL firmware variant does not support cross-brand TTL. It only provides P-TTL support via radio with devices that are P-TTL capable. So unfortunately, you are out of luck with your Nikon-dedicated equipment.

[Class A]

I assume that all these units work in both P-TTL and TTL? The reason is that from past experience with pre flash my family are the worlds best blinkers and really adept at anticipating the flash trigger leading to quite a few closed eye shots, so I prefer to cut out the pre flash

If you want to use HSS then the V6II will always use a pre-flash.

Sadly, even if you only want to use remote power control then the V6II will also use a pre-flash. There won't be a pre-flash with the RF60x but any flash fired by a V6II receiver will produce a pre-flash when you are able to remote control its power.

The only way to avoid the pre-flash with a V6II is to forgo remote power control and set profiles to "MANUAL".

The V6 supports remote power control without implying a pre-flash by using analogue TTL rather than digital TTL power control.

[TonyW]

You're welcome! I'm pleased you found it interesting. The remote flash head zoom of course should work, but its all quite a big ask to expect full compatibility between electronic devices made by three totally independent companies, and without any specific co-operation between them. As we've been seeing on an adjacent thread here, we cannot expect everything to be seamless when there are variables between third party flashes and the way they implement the P-TTL / TTL protocol.

I agree it is a big ask to get full compatibility. TBH was hoping rather than expecting

There have been recent reports of the Yongnuo P-TTL model not remote zooming either, as well as with some Metz models, and also reports that the camera format seems to have an effect on this (eg needing to set the 'crop' mode on the K1 to get zooming going). Perhaps this is relevant to your 645 also? The Pentax flashes are designed to accommodate correct display of zoom positions for all formats (35mm, aps-c and 645), whereas the third party models probably are not. However there was a firmware update for the Yongnuo P-TTL model that I think fixed this? It might be over-optimistic however to expect the same result for a Nikon version though. But worth updating the flash if its possible.

Yes I have not been able to get zooming going on the 568EX's. I did notice that to get the flash power to operate and match on the cactus on camera (TX) with the one attached to flash (RX) you need to alter the thumbwheel to trigger the units to 'talk' to each other. Once this done then communication works normally. I cannot think of anything to help the zoom function work and maybe it will not with the Yongnuo or even with the Nikon SB600 (yet to give this a try)
Unfortunately the 568's firmware cannot be updated

Do you want to use the flash on-camera, with the Cactus V6IIsandwiched between camera and flash?

In that case, have you configured the camera system to be "PENTAX" (or left it on auto-detect) and configured the flash system to "NIKON"? You may also want to manually choose the flash model you are mounting on the V6II. I'm unsure whether this may support HSS. It may very well not work, but I guess it is worth a try.

Thanks for you input on this. Yes, the thought was to sandwich the V6 II between camera and flash, mainly to add a convenietnt and simple fill and catchlight facility with the option of HSS. Some concerns about the unwieldy nature of this and if it would put too much strain on the camera particularly in portrait orientation.

The camera system has been configured to be Pentax and the flash to Nikon (also somewhere in the menu the Yongnuo 568EX is available (flash profile I think))

There are two different kinds of firmware for the V6II.

The "multi-brand" variant supports cross-brand power control and HSS.

Only the other "X-TTL" variant supports cross-brand TTL support. Unfortunately, however, the Pentax version of the X-TTL firmware variant does not support cross-brand TTL. It only provides P-TTL support via radio with devices that are P-TTL capable. So unfortunately, you are out of luck with your Nikon-dedicated equipment.

Not the end of the world that one system not fully compatible with another and TBH not really expected - just hope against experience . So it seems if I want this kind of TTL support I must opt for either a Pentax manufactured flash or a third party Pentax compatible, Metz etc. The other option that has taken seed is to go for the Cactus RF60x

If you want to use HSS then the V6II will always use a pre-flash.

Sadly, even if you only want to use remote power control then the V6II will also use a pre-flash. There won't be a pre-flash with the RF60x but any flash fired by a V6II receiver will produce a pre-flash when you are able to remote control its power.

The only way to avoid the pre-flash with a V6II is to forgo remote power control and set profiles to "MANUAL".

The V6 supports remote power control without implying a pre-flash by using analogue TTL rather than digital TTL power control.

This may turn out to be a dumb question but if V6 set to manual would HSS work without the preflash?

The more I think about this the more interested I become in the RF60x as it would seem to be effectively adding a third V6 type controller as well as P TTL flash allowing use of other flash units albeit with certain caveats.

[Class A]

This may turn out to be a dumb question but if V6 set to manual would HSS work without the preflash?

The V6 will never cause a pre-flash but it does not support HSS natively.

There are two workaround techniques for achieving HSS involving the V6. One is the so-called "starter pistol" method and the other requires the use of a P-TTL HSS capable flash. Neither is convenient.

The more I think about this the more interested I become in the RF60x as it would seem to be effectively adding a third V6 type controller as well as P TTL flash allowing use of other flash units albeit with certain caveats.

Yes, the RF60x can be used as a radio flash trigger itself. Through the use of receivers, you could even control non-RF60x units through it.

The control over off-camera light sources is not as efficient as with a V6(II) (there is no dial so adjustments have to be made via button presses) but if you want an on-camera flash, I'd say that is the best option (flashes stacked on triggers become rather unwieldy to handle).

[TonyW]

Thanks for the added information. I have now had more time to play and found a couple of things that were causing me some issue. May be of help for anyone coming across this thread with similar set up.

1. Yongnuo 568EX (Nikon). Even when all settings seemed correct flash would not fire at HSS sync speeds i.e. nothing above 1/125 sec. The answer seems to be first fire off a shot at 1/125 or lower then change to whatever you need up to camera max shutter speed. My guess is that somehow this wakes up communication

2. The 568EX will not respond to zoom settings.

3. Nikon SB600 will respond to changing zoom