[jbrowning]

I am trying to figure out how to use my af-540fgz in hss mode using my new Cactus v6? I can get the flash to fire at 1/180 ss but not higher. The flash is set on PTTL mode and HSS, the receiver on the flash is set to receiver and then the camera have another cactus v6 set to transmitter and the ttl is showing on the screen on the cactus. Is there something else I need to setup? Oh and both cactus v6 is set to the pentax 540 profile.

Thanks
Jim

[awaldram]

Cactus V6's are not P-ttl flashes so you cannot use hss with them

You can simulate hss by using passthrough on the camera mounted V6 and a p-tt in hss mode on th v6's (oncamera) hot shoe

This will allow you to go above 1/180 you can then use the 'delay' function of the rx v6's to try and get a full flash (1:1 any flash on the v6) to extend for teh period of the shutter traversal across the frame.

For this to work you need a flash whos 1:1 flash duration exceeds 1/180 (most metz)

[Class A]

This will allow you to go above 1/180 you can then use the 'delay' function of the rx v6's to try and get a full flash (1:1 any flash on the v6) to extend for teh period of the shutter traversal across the frame.

With my K100D, I didn't need to use the delay feature up to shutter speeds of ~1/2000s.

I just optically trigger with a V6 on the main flash of an HSS-capable P-TTL flash. Only for shutter speeds beyond 1/2000s, I need to set the V6 to trigger on the pre-flash of the HSS-flash and then use a delay value.

For this to work you need a flash whos 1:1 flash duration exceeds 1/180 (most metz)

Yes, most flashguns have a flash duration longer than 1/180s at full power.

This will involve a gradated illumination of the frame though (as the flash pulse loses intensity as it dies off).

Alternatively, one can use an flash that can emit a long HSS burst without having a P-TTL connection with the camera. The RF60 is such a flash. The Godox V850 may support this manual HSS mode too, but I'm not sure.

[jbrowning]

Sorry Class A. i don't think your post came through.

[Class A]

Sorry Class A. i don't think your post came through.

Thanks!

There was a technical problem. I've edited the post now.

[jbrowning]

Ok, so I am using the Cactus V6, Pentax K5II and the Pentax AF-540FGZ. So with this set up I should be able to trigger my remote flashes (4 of them) at a speed higher than f 1/180? I am using this for Motorcycle Roadracing and really need to figure out what I am doing wrong here.

Thank you
Jim Browning

[Class A]

I am using this for Motorcycle Roadracing and really need to figure out what I am doing wrong here.

Well, AFAIC, Pentax did something wrong when they decided to disable any flash trigger signal for shutter speeds beyond the sync speed (1/180s).

This means that if you want to go beyond 1/180s then currently the only way to get a trigger signal for external flashes is to use an HSS-capable flash connected to the camera. In your case this will probably have to be the 540 FGZ, unless you have other HSS-capable flashes. The HSS-capable flash connected to the camera will give you two options to trigger external flashes.

1. trigger on the main flash output of the HSS-capable flash.
2. trigger on the pre-flash of the HSS-capable flash.

For both of the above, you need to set the V6 to Tx mode and enable optical triggering. You also need to make sure that the V6 "sees" the light output of the flash connected to the camera. So far, I just held the V6 in my left hand and held it near the Fresnel lens of the on-camera HSS-flash. I typically turn the head of the on-camera HSS-flash away from the scene, because I don't want it to contribute any light, I just need it to generate an optical trigger signal.

If you stay under a certain shutter speed -- as I wrote it is about 1/2000s for my K100D -- then you can trigger on the main flash (that's "S2 - MAIN FLASH" on the V6) and leave the delay inactive. Set all your on-camera flashes to full power so that they produce the longest flash pulse possible. The lower the power, the shorter their pulse will be and this in turn will mean that the upper part of the frame will not be illuminated.

If your external flashes allow long HSS-bursts to be activated manually then this would be another option that avoids the need to be at full power all the time and also avoids the otherwise inevitable gradation. The gradation may not be an issue outdoors, though, when the upper part of the frame is filled with sky or far away objects anyhow.

Starting with a certain shutter speed, triggering on the main flash will not be fast enough anymore. You'll notice this by a black bar creeping up from the bottom of the frame. This means the light from the external flashes comes in after the second curtain has started moving already. Now is the time to switch to triggering on the pre-flash. Doing just the latter, however, would mean the external flashes would start firing too early. There is a time gap between the pre-flash and the main flash that the camera uses for processing the metering results from the pre-flash, stopping down the aperture, etc. That's why you need to dial in a corresponding delay time on your V6. On my K100D that's around 85ms, but unfortunately that time depends on the aperture used because smaller apertures take a little bit longer to set.

If you really need to use pre-flash triggering ("S1 FIRST FLASH" on the V6) then you'll have to experiment with the delay time for certain aperture values to make sure the external flashes fire at the optimal point in time.

I'd try to use shutter times that still work with main flash triggering, because this avoids dealing with varying delay times.

N.B., high shutter speeds are not necessarily ideal to stop action because the shutter curtains will always take at least 1/180s to travel over the sensor. You'll avoid local blur, but you'll get an effect similar to that of "rolling shutter" in video.

It can be better to set the shutter speed to 1/180 and reduce the ambient light by a combination of small aperture and ND filter. The main light would then have to come from external flashes set to 1/2 power or lower. The lower you can set them, the better they'll stop the action, but of course you'll need lots of flashguns at lower power to fight the small aperture and/or ND filter.

---

Last edited by Class A; 06-15-2014 at 08:25 PM.

[jbrowning]

Thanks for the reply Class A. Here are two examples that I came away with today. Now this was with only one 540 flash and it was attached to the hot shoe.



Sports Flash Photgraphy 1 - Pentax User Photo Gallery

And here is the second with the same set up as the first one.



Sports Flash Photgraphy 2 - Pentax User Photo Gallery

I do notice a little bit of a blur. I'm not sure if that is from me, the rider or if I'm needing a faster shutter speed. I don't think I would need to go over 1/1000 shutter speed though.

Thanks
Jim

[jbrowning]

So what do you all think? Should I worry about going faster than 1/180 with the flash? I'm pretty happy with these. Sure wish the flash would cycle a little faster. Will need to look into some eneloops for the flashes.

Thanks
Jim

[panoguy]

So what do you all think? Should I worry about going faster than 1/180 with the flash? I'm pretty happy with these. Sure wish the flash would cycle a little faster. Will need to look into some eneloops for the flashes.

Thanks
Jim

They look great, Jim! You really know how to pan with your subject, but of course you need to go FASTER! Always FASTER!!!

Hight speed sync (HSS)! External power pack! Eneloop XX's! Go go go!

[jbrowning]

Thank you very much for the reply. I have been shooting Motorcycle Road Racing for about 5 years now and it has taken me all that time to finally get to where I'm at. The next thing I will be looking at are the eneloops for the 4 flashes that I use.

GO FAST OR GO HOME!!

[chickenandavocado]

does the transmitter with the TTL flash mounted need to know what model is being mounted?

reason i ask is, my sigma 610 isnt supported by the v6 (only works as manual flash), just want to know if there's any possibility of off camera ttl with the sigma 610 mounted on my v6

[awaldram]

does the transmitter with the TTL flash mounted need to know what model is being mounted?

reason i ask is, my sigma 610 isnt supported by the v6 (only works as manual flash), just want to know if there's any possibility of off camera ttl with the sigma 610 mounted on my v6

Should be fine (no promises)

To operate in p-ttl mode the on camera (on v6) flash must have the trigger operating in pass though mode.

It certainly works fine for my metz 45 Digital in p-ttl mode

[Dan Rentea]

Hello!

I have a question about this trigger (Cactus V6). Let's take an example (see the image bellow):

I'm at a photo shoot using three flashes, two manual flashes (Yongnuo) placed on tripods and one flash that supports P-TTL (Metz 58 AF-1) set on the camera (each flash is triggered by Cactus V6).

The question is: I will be able to trigger all 3 flashes at the same time, choosing the power of the two manual flashes placed on tripods using the Cactus V6 trigger and leave the main flash mounted on the camera in P-TTL mode?


how do i print screen

[Class A]

I will be able to trigger all 3 flashes at the same time, choosing the power of the two manual flashes placed on tripods using the Cactus V6 trigger and leave the main flash mounted on the camera in P-TTL mode?

In principle, that is possible with the V6.

In your case, however, you won't be able to remote control the power of your two off-camera flashes, because the YN560-III is not supported by the V6 for remote power control.