High Speed Flash has anyone used it.

[ericmark]

I have a Pentax K10D but the hot shoe flash gun I use is quite old so was looking at replacing it with one which has the extra contact to get full dedication with camera. When looking at new flash guns there is a huge jump in price to get High Speed Flash and wireless function and I wonder if worth the extra money? I have to date only had one picture where the slow sync speed was a problem. A water fall and natural light caused trails on each droplet. Some day I will return and try a night shot. However it seems the high speed flash will remove this problem and so may be worth the extra money. So has any one tried it. I include an explanation as I will guess many readers will have never have heard of it so may not understand the question.

This allows one to use the flash in combination with shutter speeds faster than the camera's sync speed, which in current Pentax models is 1/180th of a second. At shutter speeds exceeding that, there's never actually any time when the entire sensor is exposed at once: there's just a fast-traveling slit between the front and rear shutters. HSS works by creating many very fast pulses rather than one bright flash, so the tradeoff is reduced power. This isn't necessary (in fact, quite the contrary) for freezing motion — for that, you need to look at the actual flash duration (which is generally much, much shorter than the shutter speed).

At the moment I use a Vivitar 3500 on camera (low hot shoe voltage) and another old high voltage flash gun with a flash triggered remote. Since I also use some old lenses it is used in the main on manual camera settings but although the sensor will change the output of the flash there is no manual setting. Since I want off camera flash my options are to buy a very cheap low output flash to use purely to trigger the other flashes or get an expensive one with all bells and whistles.

So interested to hear what others have found.

 

[frankman]

If I'm reading this correctly what you really need is a flash with a much higher output. Then you can use a smaller f-stop so that the ambient light isn't enough to influence the exposure. Or try using a higher ISO and see how that works.

The shutter must be fully open, at the moment of flash, if you don't want any 'trails'. So the high speed flash unit, producing a series of flashes, won't help.

 

[ericmark]

Thank you I will need to try and see how it works. Think power wise of flash just need a smaller water fall. Or darker water fall.
Increasing or decreasing aperture or ISO will not help as it's the ratio between ambient light and flash generated light which causes the problem so either need to reduce ambient light i.e. dark day or night or increase flash power.
By increasing shutter speed it would reduce ambient light but the multi flash of a high speed flash will also reduce flash output so what I gain on roundabouts likely I will lose on the swings hence the question to see if others had tried the same thing.
Can't really get my head around how it helps in anything but fill in flash but since never used one don't really know.
Maybe old film camera that does not use a focal plane shutter is the answer?

 

[frankman]

Reducing the aperture will let less ambient light in, and a higher output flash will have more impact.

Try it out. Camera on manual settings. Set the shutter speed to its highest sync speed - probably 125th/sec, and reduce the aperture so that you eliminate most of the ambient light. The darker the conditions the easier it is. Fire the flash at its highest setting and see how much of the foreground it will illuminate. Obviously the more powerful the flash, the greater the area it will fill. You can always sync several flash guns together to give you more light.

The high speed flash, I believe you're talking about, will give a strobe effect and not a single frozen subject.