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07-18-2016, 06:49 AM - 1 Like   #1
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Cactus V6II examples

There's a lot of chatter about HSS and Cactus gear, I thought it could be interesting to post up some examples of it in use. Here's a photo from my K3, with an RF60 flash, triggered with a Cactus V6II trigger. It just works, you just spin the dial up to 1/8000. So nice.



07-18-2016, 07:20 AM   #2
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I hate technology. I just picked up a set of V6 triggers this spring.
07-18-2016, 07:29 AM   #3
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QuoteOriginally posted by mattt Quote
I hate technology. I just picked up a set of V6 triggers this spring.
Well, the nice thing is that I think the new trigger with play with them... I have two v6 triggers, I'm looking forward to making them do something with my pentax flashes... :-)
07-18-2016, 10:07 AM   #4
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Will the wireless trigger fire HSS wireless or do you have the flash connected to the hot shoe?

07-18-2016, 10:33 AM   #5
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QuoteOriginally posted by Blacknight659 Quote
Will the wireless trigger fire HSS wireless or do you have the flash connected to the hot shoe?
Flash is remote, trigger connected to the camera!
07-18-2016, 11:11 AM   #6
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Thanks for the update. The Cactus V6ii looks like a winner for Pentax speed lite users. Would love to see more examples, specifically outdoor portraits if you have them.
07-18-2016, 12:04 PM - 2 Likes   #7
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QuoteOriginally posted by fwbigd Quote
Thanks for the update. The Cactus V6ii looks like a winner for Pentax speed lite users. Would love to see more examples, specifically outdoor portraits if you have them.
Here's a quick self portrait to demo it, I'll try to post more later. This was in EV 14 or 15 light. You're not exactly pushing a lot of light out of a little speedlight with HSS, it's a whole different world.
07-18-2016, 04:27 PM   #8
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QuoteOriginally posted by mattt Quote
I just picked up a set of V6 triggers this spring.
As bobbotron mentioned, the V6 will work with the V6II (once the respective firmware update has become available).

You won't be able to drive HSS-capable flashes at shutter speeds higher than the sync-speed in HSS mode with a V6 receiver (one needs a V6II receiver for that), but the V6 will play with the V6II at standard shutter speeds, and will also support PowerSync.

PowerSync (aka "HyperSync") is a technique where a speedlight is fired at full power in order to exploit the relatively long flash duration speedlights exhibit at full power (often ~1/125s). The flash durations are long enough to support shutter speeds beyond the sync-speed. You get even more power out of a flash this way (compared to HSS).

The downsides are:
  1. The exposure contribution from the flash is graduated. In contrast, HSS, will provide even illumination. The V6II allows you to fine-tune the timing, though, which may help to adjust the effect to the scene.
  2. Having to run a flash at full power makes it harder to achieve lighting ratios with multiple flashes. One has to use distance in order to control power.


07-18-2016, 06:57 PM   #9
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My dog helped out - there was a good deal of shade going on here, but the cedar trees behind her were illuminated quite brightly by the sun.



07-22-2016, 04:38 AM   #10
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One more. These strobes don't push out a ton of light in HSS mode (unless I'm doing something wrong) - you need your flash pretty close to your subject to get illumination, I can see why cactus sells packs of the flashes. That said, I'm pretty sure it's the nature of the HSS beast.

07-22-2016, 05:38 AM   #11
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QuoteOriginally posted by bobbotron Quote
One more. These strobes don't push out a ton of light in HSS mode (unless I'm doing something wrong) - you need your flash pretty close to your subject to get illumination, I can see why cactus sells packs of the flashes. That said, I'm pretty sure it's the nature of the HSS beast.

If I understand HSS, you aren't getting a single pop of light, rather several short bursts at a relatively high power. Since this is a common problem, most photographers will purchase 2 - 3 flashguns and attach them to a multi bracket. This way, they can up the overall output.
07-22-2016, 06:20 AM   #12
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QuoteOriginally posted by bobbotron Quote
That said, I'm pretty sure it's the nature of the HSS beast.
Yes, as Blacknight659 explains, HSS lighting consists of very high-frequency bursts. In order to achieve even lighting over an extended period, many smaller pulses combine into a long burst. There is only a limited amount of overall energy and if its spread out over a longer time (to avoid black bars or a graduated exposure) then the peak power cannot be as high.

I haven't measured the light loss due to the above yet, but from what I read it may range from 1-3 stops.

The biggest contributor to HSS lighting being limited in power, though, comes through the fact that once shutter speeds go beyond the sync-speed (1/180s for most Pentax DSLRs; 1/200s for the K-1), increasing the shutter speed also cuts down on the flash exposure. At lower shutter speeds, shutter speed does not influence flash exposure as there is always sufficient time to make a quick full contribution to the full frame. Once the shutter starts to only expose parts for the frame as a moving slit, however, only part of the flash's energy reach a particular area on the frame. An alternative way to understand this phenomenon is to look at HSS lighting as continuous light, that is always affected by shutter speed.

As a result, at 1/8000s, the contribution of HSS lighting to the exposure is about 5.5 stops lower than it is at 1/180s. That's why one almost cannot have enough speedlights to compensate. Eight speedlights only compensate for 3 stops, compared to a single one.
07-22-2016, 05:38 PM   #13
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Another good way to visualise this light / power loss during HSS flash bursts, is that as the 'moving slit' of the shutter travels across the sensor area, the majority of the frame is closed .... and most of the light from the flash is actually just hitting the closed area of the shutter, so its not actually reaching the sensor at all.

The other conundrum with HSS is that you really are already 'up against the buffers' with everything ...... if you need more flash power, then some normal routes to that don't work ... eg, you can't raise ISO because that increases the ambient exposure and needs an even shorter exposure time to compensate, and that cancels out any flash power gain..... likewise for a wider aperture. So really, for HSS you might as well always use ISO 100.

Really, the only things you can do, apart from using the multple flashes as said above, is the move the flash closer to the subject or try something like the Gary Fong Powersnoot, which does concentrate and intensify the light, bringing back lost power. It is not a soft light source however, but works well when quite close.

Last edited by mcgregni; 07-22-2016 at 05:45 PM.
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