[MD Optofonik]

Is anyone making an HSS radio trigger that will work with a Pentax camera and HSS compatible flash? Every thread I've read brings up P-TTL and pretty much turns into a conversation about P-TTL instead of HSS. Since I don't care about radio triggers that work with P-TTL these threads don't end up being very helpful in my research. I'm only interested in radio triggers that will transmit and receive HSS.

[vonBaloney]

Is anyone making an HSS radio trigger that will work with a Pentax camera and HSS compatible flash? Every thread I've read brings up P-TTL and pretty much turns into a conversation about P-TTL instead of HSS. Since I don't care about radio triggers that work with P-TTL these threads don't end up being very helpful in my research. I'm only interested in radio triggers that will transmit and receive HSS.

I notice when using my Cactus v5 triggers, the hot shoe will not activate (the transmitter is on the hot shoe) if you set the shutter speed higher than the normal sync speed. Several times I have been going crazy trying to figure out why the trigger won't fire and then I realize I had set the body to 1/250s or something instead of the 1/180s sync speed (or slower). So is there even a way to activate such a trigger if it does exist?

[enoeske]

The reason the HSS discussion always devolves into a P-TTL discussion is because HSS is a part of P-TTL. You cannot have HSS without P-TTL. So, if you want radio triggers that do HSS, they must do P-TTL.

[top-quark]

You might be able to get what you want using an old PC sync cord that doesn't carry a TTL signal. Most radio triggers have a sync input and so long as you can fool the camera into thinking that it doesn't have a flash attached you can dial in whatever shutter speed you want. If you can make this work, you'll have to turn the flash power down so that the flash duration is less than the shutter speed, otherwise you'll have no chance of syncing.

If you have a P-TTL-capable flash, you can buy a cord to use P-TTL flash off camera. I have a Lastolite P-TTL cord that cost me about £25

It'll help if you let us know what you're trying to achieve. For example, if 1/180 is too slow to shoot wide open, then you can use a neutral density filter so that you don't need a faster shutter speed in the first place.

[jboyde]

The reason the HSS discussion always devolves into a P-TTL discussion is because HSS is a part of P-TTL. You cannot have HSS without P-TTL. So, if you want radio triggers that do HSS, they must do P-TTL.

...and unfortunately, the only way you're going to be able to do that is to use an on-camera flash to trigger your other flash through HSS. As far as I know, the pop-up flash cannot be used as a commander with HSS but you can use it as a wireless commander till you hit the max sync speed (1/180). One day, Pentax will keep pace with competitors and offer a wireless solution that isn't IR and can use HSS/Pttl. If you get a Metz 48 Af-1 or the like you can do this inexpensively. The cheaper pentax flash (Af360) doesnt have a swivel head so unless you're using it indoors, where the flash can bounce around the room, the remote flash won't see it if its behind you.

[MD Optofonik]

You might be able to get what you want using an old PC sync cord that doesn't carry a TTL signal. Most radio triggers have a sync input and so long as you can fool the camera into thinking that it doesn't have a flash attached you can dial in whatever shutter speed you want. If you can make this work, you'll have to turn the flash power down so that the flash duration is less than the shutter speed, otherwise you'll have no chance of syncing.

No PC sync on either of my camera bodies.

For the sake of learning more, how would a lower power setting allow HSS? It's my understanding that, during exposure, HSS strobes the flash unit at a high rate of speed to provide coverage of the entire frame.

f you have a P-TTL-capable flash, you can buy a cord to use P-TTL flash off camera. I have a Lastolite P-TTL cord that cost me about £25

It'll help if you let us know what you're trying to achieve. For example, if 1/180 is too slow to shoot wide open, then you can use a neutral density filter so that you don't need a faster shutter speed in the first place.

I would like to have the ability to stop motion using multiple off camera speelights at varying distances.

[top-quark]

No PC sync on either of my camera bodies.

For the sake of learning more, how would a lower power setting allow HSS? It's my understanding that, during exposure, HSS strobes the flash unit at a high rate of speed to provide coverage of the entire frame.






I would like to have the ability to stop motion using multiple off camera speelights at varying distances.

You are correct that HSS involves strobing the flash. Imagine, however, that you're using a flash on manual (as is likely if you're using radio triggers). A full power flash blast lasts around 1/1000 second. Reducing the power of the flash does not reduce the intensity, it reduces the duration. That's why reducing the power might give you a better chance of capturing the flash if you can persuade the camera to fire. I just did an experiment with my radio trigger, which only has a contact for the sync pin. While I could dial in shutter speeds faster than 1/180, the flash didn't trigger. I switched to Tv and thought that I was able to use speeds faster than 1/180 since the flash was firing. However, the camera overrode me - EXIF showed 1/20 or so. I don't have a PC-sync cord handy to try seeing whether shutter speeds faster than sync are possible using one of those and since your camera doesn't have a PC-sync socket, that possible method is moot.

Note, however, that you don't need faster than 1/180 to stop motion when using flash. All the exposure of your subject is done by aperture, ISO and flash - shutter speed doesn't get a look in. Shutter speed controls exposure of the surroundings that flash doesn't illuminate. Since flash duration is 1/1000 second or less, it will stop motion very effectively.

[MD Optofonik]

You are correct that HSS involves strobing the flash. Imagine, however, that you're using a flash on manual (as is likely if you're using radio triggers). A full power flash blast lasts around 1/1000 second. Reducing the power of the flash does not reduce the intensity, it reduces the duration. That's why reducing the power might give you a better chance of capturing the flash if you can persuade the camera to fire. I just did an experiment with my radio trigger, which only has a contact for the sync pin. While I could dial in shutter speeds faster than 1/180, the flash didn't trigger. I switched to Tv and thought that I was able to use speeds faster than 1/180 since the flash was firing. However, the camera overrode me - EXIF showed 1/20 or so. I don't have a PC-sync cord handy to try seeing whether shutter speeds faster than sync are possible using one of those and since your camera doesn't have a PC-sync socket, that possible method is moot.

Note, however, that you don't need faster than 1/180 to stop motion when using flash. All the exposure of your subject is done by aperture, ISO and flash - shutter speed doesn't get a look in. Shutter speed controls exposure of the surroundings that flash doesn't illuminate. Since flash duration is 1/1000 second or less, it will stop motion very effectively.

I'll try the same test and see what happens. Don't imagine anything different but it's worth trying. Heck 1/180 is still faster than "back in the day" so I'll not complain.

[enoeske]

I would like to have the ability to stop motion using multiple off camera speelights at varying distances.

Indoors or out? Indoors is very easy since 1/180 is usually enough shutter speed to kill almost all the ambient light. Outdoors can be tough because its tougher to kill the ambient with 1/180. You can ND filter the lens which is usually a bit more effective than going to HSS.



ISO: 100
Exposure: 1/160 sec
Aperture: 8.0



ISO: 200
Exposure: 1/180 sec
Aperture: 11.0

[MD Optofonik]

Indoors or out? Indoors is very easy since 1/180 is usually enough shutter speed to kill almost all the ambient light. Outdoors can be tough because its tougher to kill the ambient with 1/180. You can ND filter the lens which is usually a bit more effective than going to HSS.



ISO: 100
Exposure: 1/160 sec
Aperture: 8.0



ISO: 200
Exposure: 1/180 sec
Aperture: 11.0

Nice. That's encouraging.

[top-quark]

Just in case anyone else is interested, using a PC-sync cord doesn't work either. Not with a K-5 at least. Tv lied, just as it did with a radio trigger on the hotshoe.

Here's a link to a Strobist article about doing what the OP wanted to achieve:
Strobist: Control Your World With Ultra-High Sync

It is possible but seemingly not with a Pentax camera.

[amoringello]

Just in case anyone else is interested, using a PC-sync cord doesn't work either. Not with a K-5 at least. Tv lied, just as it did with a radio trigger on the hotshoe.

Here's a link to a Strobist article about doing what the OP wanted to achieve:
Strobist: Control Your World With Ultra-High Sync

It is possible but seemingly not with a Pentax camera.

Nope, not possible. Pentax cripples their cameras by disabling the sync port and the center hot shoe pin when speeds are over 1/180th second.
PTTL is what communicates with the camera to allow communication beyond 1/180 second shutter speed.

Your only option is to get a PTTL HSS flash, and hack that so your non-PTTL flash fires when the PTTL flash would fire (and somehow ignore pre-flashes).
As also described here, there is much more to HSS than simply firing the flash with a high shutter speed.
But you might at least be able to get one shot working and deal with the black bar from the closing curtain... of course this is expected and is the same issue with any camera with the same type of mechanical shutter. An issue any intelligent person can work around or work with, and why it is a popular and sometimes welcome "feature" of how these systems work.