Cactus V6 Review

Further Special Features

The V6 does a lot more than "just" control the power levels of flashes:

Camera remote trigger

Just like the Cactus V5, the V6 can be used as a remote shutter release for a camera. The required cable is camera-specific and an optional accessory.

With a receiver connected to the camera, the test button on a transmitter essentially becomes the shutter release button of the camera. In other words, half-press for AF (also works continuously in AF-C mode, as long as AF is assigned to shutter button half-press), bulb mode, rapid firing, combination with self-timer, etc. are all supported.

If the camera is set to bulb mode, the shutter will be open as long as the user presses the trigger button on the remote transmitter. However, to save the user from keeping the button pressed for extended periods of time there is a change in operation after two seconds. The transmitter signals this mode change by turning off the green confirmation light. One can then let go of the button. A further press of the button after an arbitrary time, will close the shutter again.

Note that by using one V6 as a transmitter on one camera and another V6 as a receiver with a shutter release cable connected to another camera, one can take two photos from different angles with a single press of the shutter release button.

Relay Feature

Sometimes one wants to use a radio remote shutter release and use off-camera flash at the same time. With a Cactus V5 this required at least four V5 units (one release transmitter in hand, one release receiver connected to the camera, one flash transmitter on top of the camera, one flash receiver connected to the off-camera flash).

The “relay” mode of the V6 enables the same scenario with just three V6 because the V6 receiver connected to the camera can double as the shutter release receiver and the off-camera flash transmitter. One just needs to mount the V6 on the camera’s hot-shoe and connect it to the camera remote shutter release port. The new “relay” mode has the following advantages:

• one unit less required.
• channel clash is automatically avoided; there is no more need to explicitly maintain different channels for the two “release” and “flash” pairs.
• the in-hand release unit allows manipulating the power levels of all off-camera flashes. Any power level changes you make using the in-hand release unit will be automatically relayed through the on-camera unit to the off-camera units.

Trigger Delay

Delaying the effect of a trigger event can be used to:

• emulate second-curtain sync.
• optically trigger on an HSS pre-flash and delay the contribution of manual flashes so that they contribute to the HSS’s main flash.
• use a hand-held V6 to trigger both camera and off-camera flash(es) to achieve HSS / HyperSync without any dedicated Pentax flashes.
• achieve multi-exposures from different flashes using different angles.
• a “bullet-time” effect when remote releasing multiple cameras.
• etc.

A V6 supports delays from 1ms up to 10s.

A very nice touch is that the delay can be turned “off” without losing the delay value. One can thus simply return to a delay value that worked for a particular application by turning the delay “on” again, without remembering or re-establishing the value.

Another very useful aspect is that changing the delay value in the menu has an immediate effect. This speeds up determining desired delay values considerably since one does not have to confirm a value or even leave the menu in order to do a test shot.

However, there is room for improvement regarding how delay values need to be manipulated. Currently, of a four digit number, one can only change one digit at a time. This makes it more cumbersome than necessary to keep adding 4ms from test to test, for instance, or reduce the value by just 2ms again, because chances are that such adjustments will require a carry over to more significant digits. It is a bit tedious having to step through all digits again to correct them all.

UPDATE: Starting with firmware V1.0.156, the adjustment of delay values has become a lot better. It is no longer necessary to manually take care of carry over events between digits.

Finally, I believe the V6 should use its main display to indicate whenever a non-zero delay is used. Otherwise one may forget about a delay value that one used on a previous session and wonder why flashes appear to misfire. The V6 already displays "REL" whenever the relay mode is active, so adding a similar indicator for a non-zero delay value seems logical.

Optical Triggering

The V6 can trigger on the pre-flash or main flash of another flash, depending on a menu setting. One application for this is to add an “optical slave” function to a flash that does not have this feature.

Look Ma, (almost) no TTL! One on-camera P-TTL HSS flash optically triggering a V6 that in turn triggers two non-TTL off-camera flashes. Shutter speed: 1/750s. V6 delay value: 95ms.

However, the most useful application, AFAIC, is to trigger on the pre-flash of an HSS-capable flash and then use a delay to make the trigger coincide with the main flash of the HSS flash. One can thus use multiple manual off-camera flashes to contribute to an HSS exposure, i.e., an exposure with a shutter speed faster than the sync-speed of the camera (1/180s for Pentax).

The majority of speedlights produce a full power pulse that lasts longer than 1/180s, e.g., 1/125s is a typical for a T.1 figure (→ do not use 1/180 if you want to squeeze out maximum power). Manual flashes set to 1/1 power will thus illuminate the whole frame without causing any banding.

When Cactus RF60 are triggered, they can be set to a special HSS mode and will then fully illuminate the frame even at power level settings lower than 1/1. They achieve this by producing long bursts of light, very similar to what a system-specific flash does in HSS mode.

BTW, if you use an RF60 in combination with a V6 as explained above, make sure though that after activating HSS on the RF60, you turn off optical triggering on the RF60. The latter automatically turns optical triggering on because it assumes that you will want to use it to trigger on the pre-flash of the on-camera P-TTL flash. If you do not manually undo this step then the RF60 will optically trigger (too early since it does not have its own delay value set) instead of being triggered by the delayed trigger signal of the V6. This bit me in my early testing attempts.

The section on "High-Speed Sync" in the RF60 flash review  expands a bit on the details of obtaining HSS from off-camera flashes.

Having said that, since light output in HSS mode is reduced -- some of the energy needs to be used to produce a "long" burst -- you will typically find yourself at 1/1 power anyhow, unless you are using multiple RF60 in one group in order to multiply the power output.

N.B., currently with a Pentax DSLR, using optical triggering on a pre-flash is the only way to obtain a "pre-sync" signal. Canon/Nikon users can use an on-camera radio trigger that pretends to be an HSS-capable flash and thus obtain a pre-sync signal that could be fed to a V6 via a sync-port connection cable. Alternatively, Canon/Nikon users can also put such a system-dedicated trigger (supporting E-TTL/i-TTL respectively) on top of a V6 in TTL pass-through mode and thus not only forgo the sync cable but also combine manual flash levels with TTL automatic exposure. No such system-specific triggers exist for Pentax, though.

On-Camera Flash Control

Multi Hot-Shoe The hot-shoe layout accommodates TTL pass-through for Canon, Fujifilm, Nikon, Olympus, Panasonic, and Pentax.

The female hot-shoe of a V6 continues to work when a V6 is used on-camera.

The V6 shields the camera from any high flash trigger voltage, allowing old flashes to be used safely. One thus gets the functionality of a protection device, e.g. the Wein Safe-Sync, that costs $49.49 on its own.

There are two ways in which an additional on-camera flash can be supported:

1. TTL pass-through: The V6 essentially pretends to not be there, thus allowing the on-camera flash to use all its native (P-TLL) features.
   Note that pressing the shutter release button on the camera will fire the flash and trigger the V6 only if the shutter speed does not exceed the sync-speed. Unfortunately, Pentax cameras do not use the centre pin for triggering an on-camera flash in HSS mode. It is thus not possible to “steal” the HSS trigger signal, so optical triggering remains the only option for letting manual flashes contribute to an HSS exposure.
2. Manual flash: The V6 controls the power level of the on-camera flash manually, as a fifth group, if you like. Chances are the dial of the V6 will allow quicker power level changes than the user interface of the flash.

Note that the V6's multi hot-shoe features holes for the locking pins of Canon, Nikon, and Pentax equipment. The locking pin of my Pentax dedicated Metz 58 AF-2 engages very well, providing for a rock solid mount. The locking pin of my Canon 540 EZ, however, did not engage, no matter how hard I tried. I had to use considerable force, but I could still slide it off the V6's hot-shoe after mounting. It appears that the EZ series had their locking pins in a slightly different position and that the Canon/Nikon locking pin hole is designed to work with the more modern EX series.

Zoom Level Control

If you own Cactus RF60, you can remotely control their zoom settings with the V6. The zoom setting control very much works like the power level control; all flashes in one group share the same zoom setting.

One can quickly toggle between adjusting power levels and zoom settings by pushing in the dial (or pressing “OK”). However, this means one cannot have both “zoom setting control” and the “adjustment accelerator” at the same time. A menu setting controls the choice. I would have preferred to have the zoom control assigned to a long-press on “OK”. Losing the quick adjustment accelerator is a shame. Maybe there is a yet unknown better use for a long-press on the “OK” button?

Ultra-Short Flash Duration

The V6 supports an (optional, menu-enabled) “Lo power” power level for analogue TTL flash models that reduces the power level below the standard minimum of 1/128 power.

The lower the light level of a speedlight, the shorter the flash pulse becomes, so this extra level may come in handy for high-speed photography. See the respective section on the “Measurements” page for further details.

Multi-Functional and Flexible Dial

The V6’s dial allows very quick adjustments of values and has an extra “push-in” functionality. Pressing on the dial mimics pressing the “OK” button. This considerably speeds up working with the V6 as you can select and enter menu items, confirm values, etc. just by using the dial.

One particularly useful application of the “push-in” functionality is toggling the “adjustment accelerator” mode.

Would you like to increase a power level (or other values) by turning the dial clockwise or rather anti-clockwise? Different brains seem to be wired differently so luckily the V6 allows you to change the default through a menu setting.

USB port

A mini-USB port supports firmware upgrades. This ensures that:

• bugs can be ironed out,
• compatibility issues can be addressed,
• flash profiles can be added, and
• it even opens up the possibility of future feature additions.

Currently, the firmware updater software only runs on the Windows platform but there are plans to make it available for the Macintosh platform as well. In the meantime, Macintosh users may use Vmware fusion with a Windows XP system and USB pass-through to run the Cactus Firmware updater. The software installs itself and performs the upgrade process very quickly. After an update, all parameters are reset to default values and any flash profiles will be lost, but one can first copy these to another receiver and then copy them back.
UPDATE: Starting from firmware version V1.0.152, profiles are preserved during a firmware update.

The mini-USB port can also be used to connect an external power supply (5V, 1A). For instance, an iPhone charger could be used to power a V6 so that you don’t have to worry about battery levels. Note that it is not possible to recharge batteries in the V6 this way, though.

LCD Backlight

The LCD backlight can be configured to be (always) “off”, (always) “on”, or turn itself off after 5s or 15s.

Sleep mode

The V6 can be configured to turn itself off after 15min or 60min of inactivity to preserve batteries. Luckily, there is also an “OFF” setting in case you do not wish to find a V6 inactive just because a setup took longer than anticipated.

Note that re-activation per radio signal is not supported. Powering the radio receiver to listen for activation signals would defeat the power-saving purpose of the sleep mode.

Low Battery Indicator

The battery status is indicated on the LCD with a battery symbol and the status LED will start blinking every three seconds once the battery level becomes very low.