[awaldram]

I phrase it differently: Cactus V6 has a pass-through hotshoe that can accommodate Pentax, Nikon, Canon flashes that offer TTL metering. But it is useless because the Cactus V6 and RF60 does not offer remote TTL function. Why it is useless? It is useless because when you use the Cactus V6 or RF60, the other Flashes become manual only even if they are $400 flash units. In other words, if you use any off camera flash, it falls back to manual, in that situation, Yongnuo does the same for cheaper. And for the price of a Cactus combo, I can have a Metz 52 for Pentax which supports TTL metering.

As I'm on of those who uses P-ttl with Cactus V6's I'd like to dispell some complete misnomers

You can easily mix and match P-ttl off camera and V6 manual control flashes you just have to remember you 'manual' flashes becomes the ambient exposure and the P-ttl the 'flash' exposure.
Anyone used to Pentax exposure flash algorithms will fully understand that .

How I often use them

scenario

Large dance floor , moving subjects but require well lit backgrounds and fill lit subjects.

solution

2 V6's firing large flashes opposite corners exposure set using the easy to use on camera group/power settings 1stop low.
3 P-ttl flashes V6 on camera set pass through flash on camera set wireless P-ttl , other flashes P-ttl slave in other corners . Flash ratios set to preference/fill requirement.

Result

You can walk anywhere within the quadrant firing the camera with abandon and the ambient/fill will remain constant , though the static guns will alter as you move closer farther away from the point source the P-ttl flashes will dynamically compensate by upping and downing their power.

[biz-engineer]

You can walk anywhere within the quadrant firing the camera with abandon and the ambient/fill will remain constant , though the static guns will alter as you move closer farther away from the point source the P-ttl flashes will dynamically compensate by upping and downing their power.

Yes, I think I understood that. So, you need a base TTL system and the Cactus V6 allow you to add more flash units manually adjusted for filling a base level of ambient light. My point is rather that the RF60 is a manual flash with radio control and triggering. The V6 documentation indicates that the Tx/Rx does not transmit TTL info nor zoom level to the remote flashes.

[awaldram]

Yes, I think I understood that. So, you need a base TTL system and the Cactus V6 allow you to add more flash units manually adjusted for filling a base level of ambient light. My point is rather that the RF60 is a manual flash with radio control and triggering. The V6 documentation indicates that the Tx/Rx does not transmit TTL info nor zoom level to the remote flashes.

You stated the p-ttl pass through was useless... I explained what I used it for.

Perhaps you miss-understand what passthrough means.?

It has nothing to-do with transmitting any data over RF it is feeding p-ttl data from the camera hot-shoe to the hot-shoe fitted on top of the module hence allowing both P-ttl remote flashes and manual remote flashes to be used at the same time.

To do what you accuse the function of being useless for you need some method of transmitting unique ID data to and from the p-ttl flashes so they can uniquely configure themselves after the pre flash.

This is why the Acom RF p-ttl trigger is of limited use as it carries no such data and is therefore not a P-ttl wireless system ..... the oakatec units are because they convert light to RF and back again at the flashes so carry all the ID data.

The Cactus V6 units would be P-ttl RX compatible if a TX unit was designed that could convert P-ttl ID's into channel data (A-D) as they support TTL control of flashes and bidirectional comms.

Sequence would be
1 camera to flashes all channels pre flash
1a flash to camera OK
2 camera to flashes unit A set W level B X level etc etc
2a flash to camera OK
3 Camera to flashes all channel Fire!

[mcgregni]

Thanks for all this useful info ..... Some may be surprised to hear it, but even I am interested in mixing a manual and P-TTL system as you describe! Could you explain please a bit more about your point about the manual flashes being 'ambient', and the P-TTL being ' flash' exposures' ..... I'm not understanding that. I thought that only continuous lighting could be ' ambient' from a camera exposure point of view?

[biz-engineer]

You stated the p-ttl pass through was useless... I explained what I used it for. Perhaps you miss-understand what passthrough means.? It has nothing to-do with transmitting any data over RF it is feeding p-ttl data from the camera hot-shoe to the hot-shoe fitted on top of the module hence allowing both P-ttl remote flashes and manual remote flashes to be used at the same time. To do what you accuse the function of being useless for you need some method of transmitting unique ID data to and from the p-ttl flashes so they can uniquely configure themselves after the pre flash. This is why the Acom RF p-ttl trigger is of limited use as it carries no such data and is therefore not a P-ttl wireless system ..... the oakatec units are because they convert light to RF and back again at the flashes so carry all the ID data. The Cactus V6 units would be P-ttl RX compatible if a TX unit was designed that could convert P-ttl ID's into channel data (A-D) as they support TTL control of flashes and bidirectional comms. Sequence would be 1 camera to flashes all channels pre flash 1a flash to camera OK 2 camera to flashes unit A set W level B X level etc etc 2a flash to camera OK 3 Camera to flashes all channel Fire!

Thanks for additional explanation.

[mcgregni]

Also, does it mean that the P-TTL data is automatically fed through the V6 to any P-TTL flash mounted on the top shoe of the V6? I assume the V6 has to be switched on, but are there any settings to make on it to activate the pass-through ? Presumably, from the point of view of the P-TTL system, it doesn't know its on a V6 .... It just behaves exactly as if its directly on the camera? Do you know if camera set flash compensation is passed through also? Sorry for so many questions, but this thread is really starting to piece together some jigsaw pieces here!


(Going back to my earlier question about the manual flashes being' ambient', I've thought more now, and I think I misunderstood you at first ...... You're not meaning that the manual flashes are acting as technical ambient light, but rather that in your mental consideration of their effect, they are positioned and function in a 'background' sense, whereas your P-TTL lights are nearer the subjects and positioned more as 'main' flash lighting ..... ? Have I got it now? )

[bobbotron]

Also, does it mean that the P-TTL data is automatically fed through the V6 to any P-TTL flash mounted on the top shoe of the V6? I assume the V6 has to be switched on, but are there any settings to make on it to activate the pass-through ? Presumably, from the point of view of the P-TTL system, it doesn't know its on a V6 .... It just behaves exactly as if its directly on the camera? Do you know if camera set flash compensation is passed through also? Sorry for so many questions, but this thread is really starting to piece together some jigsaw pieces here!


(Going back to my earlier question about the manual flashes being' ambient', I've thought more now, and I think I misunderstood you at first ...... You're not meaning that the manual flashes are acting as technical ambient light, but rather that in your mental consideration of their effect, they are positioned and function in a 'background' sense, whereas your P-TTL lights are nearer the subjects and positioned more as 'main' flash lighting ..... ? Have I got it now? )

It's a cool way to think about them, as they're static once set, while the P-TTL will attempt to optimize for each shot. However it wont take the ambient flash light into effect, interesting.

[Class A]

This is why the Acom RF p-ttl trigger is of limited use as it carries no such data and is therefore not a P-ttl wireless system ..... the oakatec units are because they convert light to RF and back again at the flashes so carry all the ID data.

Are you sure the Acon is limiting in any way?

I'd be surprised to learn that the P-TTL system used flash IDs at all.

Isn't it the case that all flashes issue the pre-flash at the same time and the camera has no way of knowing which flash contributed what?

Ratios can still be established by working out an overall flash exposure and then dividing it to the flashes according to the ratios specified.

[Class A]

Also, does it mean that the P-TTL data is automatically fed through the V6 to any P-TTL flash mounted on the top shoe of the V6?

Not automatically, only after you activate TTL pass-through. This setting will remain through a power-cycle, though.

If you don't activate TTL pass-through, you can control the power of the on-camera (on-V6) flash through the V6, which can be quite handy as the dial is often easier and quicker to use than the flash controls.

I assume the V6 has to be switched on, but are there any settings to make on it to activate the pass-through ?

You activate TTL pass-through with a "long-press" on the menu button.

The display will show "TTL" and the V6 will then pass along all (P-)TTL information to the on-camera (on-V6) flash.

For this to work, you'll have to select the correct flash profile once. Often profiles for other flash models will also work; the main aspect of this is to select the correct flash system (from Pentax, Canon, Nikon, Olympus, Panasonic, Fuji, as all are supported for "TTL pass-through").

Presumably, from the point of view of the P-TTL system, it doesn't know its on a V6 .... It just behaves exactly as if its directly on the camera?

Yes.

Do you know if camera set flash compensation is passed through also?

Yes, it is.

[mcgregni]

Thanks! And thanks awaldram for referring to your mixed use ... You never know, I might just become a Pentax AND Cactus user !

[mcgregni]

And I think I'm also getting the earlier point about the manual RF triggered flashes being 'ambient' .... This is because they are not fired until after the P-TTL pre-flash, therefore the flash metering does not take their effect into account.

I'm really keen now to try a mixed system .... Thinking of going for a V6 and RF60, and using a set-up with V6 on-camera, a Pentax 540 on the V6 with pass-through active, another Pentax 540 in P-TTL Slave mode, and the RF60 triggered by the V6.

So, one question ....(and I will be going back and reading ClassA's review again) .... The RF60 has optical slave mode. Am I right to assume that this can be disabled in a mixed mode situation, so the the P-TTL flashes do not trigger the RF60, but that only the V6 signal will do so?

[biz-engineer]

This is because they are not fired until after the P-TTL pre-flash, therefore the flash metering does not take their effect into account.

That's also my experience with Cactus, that's why I wrote that the system falls back to manual as you have to adjust flash power/exposure manually, obviously each remote flash can be adjusted from the V6 RF TX.

[mcgregni]

I was thinking that I'd be happy with one manual unit, controlled from the V6 transmitter, and 2 P-TTL units, fired via the pass-through and one on-camera. Of course there will be times when I want everything manual, but I'm not yet sure if the Pentax flashes could be controlled from the V6 without other V6 receivers attached to them ?? Can they be used in their S2 mode? In which case I'm not sure where the optical trigger would be coming from ..... ?


As I have been saying a lot, I mostly use P-TTL, but for a more complex setup, say with 3 slaves, I can see the benefit of using manual of having direct power control from the camera position. Its just that at present I am happy with the P-TTL solution of a mixture of ratios, flash compensations on the flashes and global flash compensation from the camera. But in manual mode that doesn't work with optical triggering.


The P-TTL plus Cactus approach I can see as advantageous often for me ..... I often have a two flash wireless setup (like I demonstrated in the flash diffuser thread), with one on-camera flash bounced with the lightsphere But with kids moving around, even going outside where I need HSS, keeping the flash on camera without having to remove the V6 would be very quick ...... I can just temporarily switch off the slave units while working with the single on-camera in the more dynamic way. I assume the V6 pass through function allows full functioning on the Pentax flash attached on top , including HSS?


Also, would the Pass through allow wireless HSS (optically I assume) with both the 2nd Pentax slave AND the RF60 (in HSS sympathy mode)...? (I mean both firing together in sync ....im aware there has to be a delay programmed into the RF60).

[Class A]

The RF60 has optical slave mode. Am I right to assume that this can be disabled in a mixed mode situation, so the the P-TTL flashes do not trigger the RF60, but that only the V6 signal will do so?

Yes, the RF60 triggering optical triggering options include "OFF", "Immediate" (S1), and "Pre-flash suppression" (S2) (the names are mine).

Even if the optical triggering is set to "OFF", an RF60 will respond to radio signals (in the respective radio slave mode).

Happy to help in the future, but note that at the Cactus "Downloads" page you can download the RF60 and V6 manuals.

I intentionally did not write my review as a manual replacement, so you'll find the manual useful, even after having read my review again.

[Class A]

Of course there will be times when I want everything manual, but I'm not yet sure if the Pentax flashes could be controlled from the V6 without other V6 receivers attached to them ??

For every (non-RF60) flash you want to trigger via radio or even remote power control, you need one V6 receiver.

An on-camera V6 in transmitter mode uses radio signals for communication. While RF60 flashes have a V6 built-in, any other flash model requires a V6 receiver (i.e., a V6 unit in receiver mode).

For Pentax flashes to be controlled from an on-camera V6 without using extra V6 receivers, the communication would have to be optical, defeating all the advantages of radio communication. Of course, if you use a P-TTL flash on an on-camera V6 then the latter can control Pentax flashes "wirelessly" (optically) without the need for additional V6 receivers.

In which case I'm not sure where the optical trigger would be coming from ..... ?

The V6 does not use optical communication, so as I said if you want to use Pentax flashes off-camera without using V6 receivers with them, your only option is to put a P-TTL capable flash on to of the on-camera V6.

I can just temporarily switch off the slave units while working with the single on-camera in the more dynamic way.

Yes, turning an off-camera flash on or off, i.e., toggling its on/off status, is achieved by pressing the respective group button. The V6 has four dedicated buttons, so you have immediate control over up to four individual units, but of course you can combine, say two, units in one group, so that you can control both units with one press.

I assume the V6 pass through function allows full functioning on the Pentax flash attached on top , including HSS?

Yes.

Also, would the Pass through allow wireless HSS (optically I assume) with both the 2nd Pentax slave AND the RF60 (in HSS sympathy mode)...? (I mean both firing together in sync ....im aware there has to be a delay programmed into the RF60).

The "pass-through" does what it says: It passes-through all communication as is, so all P-TTL functionality of an on-camera (on V6) flash is retained.

Putting a P-TTL HSS capable flash on an on-camera V6 with TTL pass-through enabled, allows HSS flash photography and thus taking the shutter speed beyond 1/180s. Unfortunately, however, the Pentax engineers decided to still suppress the standard hot-shoe triggering signal in that case. This means that the V6 will not be triggered (it just passes the data through to the flash on top of it, but does not receiver a proper triggering signal from the camera itself). This is a pain and Nikon shows that it need not be that way.

As a result, in order to involve an off-camera RF60 (or any other flash combined with a V6 receiver) in an HSS setup, you'll have to pick one of the below:

1. optically trigger the RF60 (forgoing the radio communication the RF60 is capable of).
2. optically trigger the V6, which in turn will trigger any number of off-camera flashes via radio. Optically triggering an on-camera V6 is not hard to do, but can lead to a clumsier than necessary setup, or requires you to hold the V6 against the on-camera flash each time you take a shot.
3. use my (not yet patented ) idea of triggering a camera and flashes at the "same" time (this requires a camera release cable, which however is dead cheap).

Only with approach 3. you'll definitely have to use manual delays. With the other two options, you should be able to not use any delays unless you want to take your shutter speed above 1/2000s and need all of the the frame illuminated.