Yeah, it's pricier than I thought it would be but there is a lot to like regarding the performance. Compared to Priolite and Phottix location lighting kits (which are also compatible with Pentax cameras) the price looks more than alright, but Godox offers their AD400 for a similar amount. Alas, unless Godox fulfils their promise of a Pentax-compatible trigger, it is not really an option for us.

Cactus launched their 250Ws monolight for location lighting with a Kickstarter campaign.

Bit of a surprise move, AFAIC, but Cactus seem to be in good company with Peak Design and MagMod who also used Kickstarter to launch a product despite being established companies already.

In particular Pentaxians who already own a V6 or V6II trigger might be interested in this Li-Ion-powered strobe that should be able to replace 3.5 x regular speedlights with a very small form factor.

No worries.

That is only true for "HSS the triggering approach" (i.e., pre-sync timing).

Regarding "HSS the lighting approach", one can use RF60s in "HSS sympathy" mode to create the same light bursts that approach continuous light that you get from system-specific HSS-capable flashes. See my post above for a link to the two approaches to make use of that capability.

Not entirely sure what you mean by "High Speed Sync mode", I guess you mean shutter speeds beyond 1/180s.
Pentax disables the regular trigger signal to the hot-shoe when the shutter speed is above 1/180 and the Cactus V6 does not pretend to be an HSS-capable flash (end hence does not prevent the disabling of the trigger signal). However, there are workarounds for the V6 (see the links below).

Check out the answers I provided in one of the other posts you made about this subject

Nikons and Canons don't support HSS with a non-system specific trigger like the V6 either. They require special system-dedicated triggers in order to support HSS via radio.

Cactus posted a while ago that they are working on a successor for the V6 that will pretend to be a system-specific flash and hence support HSS natively. Until then, perhaps you can use the workarounds.

@kanfranben: I once wrote a comparison between the RF60 and some other flashes, including a Yongnuo. It's been a while, but many points still stand.

The Yongnuos cannot be beaten on price but they don't appear to be as reliable and they definitely have less features (no manual HSS sympathy mode, no delay, etc.). I personally would not wade through the jungle of incompatibilities Yongnuo have created with their three different flash systems. They have started to integrate two of them a bit, but you will always have to be very careful in which particular product to get so that it plays well with other Yongnuo products.

@judeerman62: The BFT (black foamie thing) is not a reflector or diffuser. It is a flag and is used to block light.

The idea behind it is to use existing large surfaces (e.g., walls) to bounce your flash off. The larger the surface, the softer the light will appear on the subject. However, when bouncing the flash, the latter may often spill some light on the subject directly which would lead to hard shadows and specular highlights if not prevented.

The BFT's purpose is to stop the spilling of direct light from the flash on to the subject.

Note that many portable diffuser solutions (in particular of the Stofen and Fong variety) need nearby walls or ceilings as well to function properly. They are way too small to create soft light on their own. Hence using directed bounce purposefully with the BFT to protect the subject is much more effective than lighting up the whole room indiscriminately with some overpriced tupperware gadget.

Hope this helps.

It is correct that one needs one HSS-capable flash to do flash photography where a Pentax DSLR provides the sync signal (with other brands, no such tricks are necessary, up to a certain shutter speed).

Using an HSS-capable P-TTL flash, one can use optical triggering (e.g., of a V6 very near the P-TTL flash) with simple main flash triggering up to about 1/2000s from my experience. Higher shutter speeds require a pre-sync signal which one can get by triggering on the pre-flash and using a delay in order to make the off-camera flashes trigger with the main flash.

There is one workaround that allows one to do away with a pricey HSS-capable flash. It works by triggering the camera and the flashes at the same time, using a radio trigger as a remote camera release. The required cable connecting the trigger receiver with the camera is cheap as chips, but now the flashes need a delay to compensate for the camera's shutter lag. Dealing with this delay manually is not nearly as comfortable as letting P-TTL everything automatically, but the technique works and lets one use many off-camera RF60 in HSS mode contributing to exposures at any shutter speed.

Both RF60 (flash) and V6 (trigger) will work with all of your gear. The equipment is not dedicated to a specific system.

The V6 even supports TTL pass-through (only for on-camera flashes where the V6 is sandwiched by the camera and flash) for all your brands.

Yes, the RF60 has its own tripod mount at one side. If your camera fits on top of something, the RF60 will as well without requiring a hot-shoe adapter.

Accidentally turning the dial with the forehead has never been a problem for me, but I've read about some people with that issue.

This has been addressed, however, with a firmware update quite a long time ago. This update adds an optional "lock" feature. If you activate it, you will have to unlock the dial with a short press first before you can use the dial to make changes. The dial will be locked again automatically after a short timeout following your last action on the V6. Turning the dial with the forehead therefore has no ill effects. Pressing the dial with the forehead is not really possible unless you purposefully try hard, so there are no accidental "unlockings".

I personally believe that manual control is easier to master than using automatic schemes where you need to understand what the camera and flash are trying to achieve with the combination of ambient and flash exposure and then, on top of that, need to know how to influence the decisions taken, and also be able to spot situations that will throw the automated metering approaches off their game.

When everything is manual, you can tweak everything step by step and will get consistent results every time. This makes it easy to learn what action causes which effect. A system like the V6 that supports remote power control makes it easier to make experiments and learn from them because you don't have to leave the camera position, or even open up light modifiers for access to the flashes, in order to make adjustments.

I'd say you should be comfortable shooting manual mode and should consult a good resource on basic flash photography (such as "Strobist 101", just ignoring the outdated gear recommendations). There are only a few basics to learn (such as that shutter speed does not influence flash exposure as long as you stay on or below 1/180s), but a good tutorial will make it easy to fully understand and memorise these few basic facts.

Once you have the basics on boards, off-camera flash will be fun to use and will significantly improve the quality of your images.

Last tip: With portable flashes, always bounce them off a big surface (unless you use them in a big light modifier). The "Black Foamie Thing" is one of the cheapest but also most effective flash accessories there is.