Hi Photobill, I do understand the frustration, but HSS is probably not the best technique. For motion freezing then its probably best to stick to the max Sync speed (1/180th) and use low powered flash bursts, as this produces the shortest burst of flash (like 1/15,000 - 1/20,000) ..... HSS using rapid pulses of light, equivilent to a continuous light source, which lasts for the entire 1/180th sec the shutter is open, despite the actuall shuttter speed setting .... so the effect is more likely to be a little blurred with HSS, even at those very short exposure times.

At 1/180th with a higher ISO and wider aperture you might be able to get some ambient light to record as well, so a more atmospheric and attractive background.

OK, I see that point, although there's been a bit of cross-purpose discussion here I fear .....

I just tried it again with the K7 and AF-540FGZII (on-camera, normal flash not HSS)) at low manual power settings, and I got continuous shooting of around 3.5fps, which kept going for more than 10 frames.

Tha main point I feel is that the flash actually flashed and synced with every camera cycle .... For practical purposes, to actually light anything properly, at decent exposure settings and get faster recycling than that I think you'd need some very expensive studio lights. So I don't see the limitation as it relates to hotshoe flash types as significant really.

The Waddon Ponds, on the Sutton & Croydon border in South London, is a small haven and respite from the busy main roads that dominate the area. I was lucky early this week that this one swan was very ameniable and was happy to parade around right near the ponds edge .....

Pentax K7, D FA28-105mm, around 70mm, F8.0, ISO200, 1/1000 sec

The burst you see at the end of the video is using two flashes together, there by halving the power demands so halving the recycling times. The shutter sounds you hear may not even be the actual live recording, it sounds overdubbed ..... In any case the flashes don't actually respond to every shutter sound, they only fire a few flashes, and they miss a good number of the shutter sounds, so it still looks like a 2fps or so speed of flash recycling.

If the camera is indeed able to keep firing at full burst speed in between flashes (as is implied by the sounds on the video), then there's little point id argue ..... There's no light on the subjects for those exposures, so they are wasted frames.

If this is the limitation you are referring to (ie the camera won't keep firing even though the flashes are recharging) then I don't see this as any sort of practical real limitation, apart from in the making of sexy cool promotional videos ....

The camera detects when a flash is attached and on, or a an active trigger. When you switch it off then the camera performs as if no flash attached .... So you get the 9fps ...

With the trigger on then the recycling is limited by the trigger and flash systems. Power recycling is the main aspect, as has been explained. HSS is a technique mainly for balancing bright ambient light with flash, not for achieving rapid bursts.

Unlocked, that's not correct, and the 'limitation' exists exactly the same on any camera system. Peter and Yves have clarified it further, as recycling is directly linked to battery state and power demand.

Photobook, I suspect you may be misinterpreting some aspects of what you saw being done .... It doesn't sound like you actually need 'HSS'. Could you explain in detail what you what to achieve with the flash, in terms of the actual images.

These have some very crisp feeling light, a cleanness and sense of the chilly fresh sea air. Nicely placed rocks in the 2nd one ....almost looks like you placed them there yourself!

Just had a look at the RF60 manual (I have the original model) and with alkalines it's rated to recharge from 'empty to full' in 5secs ..... That assumes fairly new batteries, so your 2.5fps (less than 0.5 sec to charge) looks good actually.

I wonder, if you want rapid flashing, perhaps you could try the 'multi-flash' mode, which fires a burst of flashes during a single exposure. You can choose the number of flashes and the gap between them. Great for moving objects.

I agree with Peter (and stu!). I think he is right about the recharging being the limitation. Really, when you add flashes into the mix then you can pretty much throw quoted camera FPS numbers out of the window!

I'm no speed demon when it comes to flash, but from tests I've done with the similarly powered Pentax AF-540FGZ flash, I'd say that 2.5 secs recycling is not too bad really. And as Peter said, HSS can add to the power demands also. That was with an on-camera flash.

There might be limitations built in to the radio transmission system also, in terms of repeat triggering. The recycling will depend a lot of the power demands on the flash ..... What Aperture, ISO and shutter speed were you using for those HSS bursts?

Based on the quoted conditions from Ricoh for the different AF technologies, I doubt that a 17-50 zoom (at least not a wide aperture one) is a candidate for PLM.