Why are my flashes not freezing up action

[cmor]

using 285hv's with 1/1000 duration, is this not short enough?



100% crop of kayaker:



100% crop of rocks on left for comparison:

[bklyn]

exif data?

[cmor]

exif data?

Didn't mean to strip it, you should be able to pull it off of the thumb. Ambient underexposed by 3+ stops.

[otter]

what camera are you shooting with?

[bklyn]

- subject is out of focus
- camera shake? were you using a tripod?
- 1/1000 is not fast enough

[cmor]

what camera are you shooting with?

Sony a700

- subject is out of focus
- camera shake? were you using a tripod?
- 1/1000 is not fast enough

Thanks for the thoughts, my observations:

-subject is in focus, everything is sharp except for the kayaker himself.

-no camera shake at 1/1000, and as above everything else is sharp.

Is 1/1000 really just not fast enough? Am I doomed with my current setup? I rarely have issues with 1/1000 shutter speeds.

[Doc Green]

Is it possible there is some additional ambient light that might be hitting on the kayaker? If so, than this could trigger additional exposure instances, while the shutter is up, of the athlete upon your sensor, leading to the blur.

[Doc Green]

Regardless as to whether there's ambient light, A potential solution might be to shoot at a different angle, one in which the movement of the athlete is minimized with respect to the plain of the sensor.

[Lonnie]

What focal length were you using? Are we seeing a reclection of the flash off the water?

[dipstik]

I rarely have issues with 1/1000 shutter speeds.

The exif says you are at 1/250?

Are the flashes on full power? And how many are you using?

It's my understanding that with small flashes, as you dial down the power the flash duration becomes shorter, whereas with studio lights, the flash duration becomes longer when you dial down the power.

So if you're blasting the kayaker at 1/1 power, the flash duration could be too long, explaining the blur? You might be better off with 2 units firing at 1/2 power? I don't know, I could be way off base here. I'm just thinking out loud.

PM Gunder or Midget, they will know for sure, and report back because I'm curious about this...

[otter]

Are you shooting with the flash on camera or off? if you are on camera and the flash is not dedicated to your camera it will probably not sync faster that 1/250. And if your speed was at 1000 on your camera you probably didn't even get the flash in the photo.

[Yeti]

Ditto -- this looks just like a flash sync issue, particularly since EXIF reads 1/250 and the A700 is spec'ed at 1/250 x-sync.

[Eldo]

Edited my post, since we need to nail down one thing before we can figure out the problem.

You said the shot was deliberately underexposed by three stops? What were the lighting conditions like that day? Was it sunny, or is that shadow from the paddle caused by the flash? And where was the flash(es) and how far away in feet? And how were they triggered?

If ambient light made the exposure (or even most of it) then the shutter synch speed is too low. If the shot was indeed made almost completely by flash (as would be the case at -3 stops) then 1/250 synch is fine since the flash duration was at least 1/1000 sec, which is what the 285HVs are at full power.

[cmor]

From the distinct shadow of the paddle on the kayak it looks like the sun was out. So using the basic rule of exposure, at 200 ISO and F 6.3 @ 1/250 you are at most underexposing by one stop, not three. That gives plenty of ambient light to result in motion blur (from the kayakers motion) with only a 1/250 shutter speed. That is why the rocks are sharp, they are not moving.

As others have mentioned those flashes are not dedicated and so can only synch at the max 1/250 the A700 is capable, so basically the flash at most provided some fill, but the motion blur is already there.

The shadow from the blade is from a flash up high to the lookers left. The was no sun, it was taken quite late in the day. The ambient was underxposed, you can see the non-flash affected water in the top of the frame.

Here's Another, 10:30 AM, similar area, way more light then the strobed shots, only 1/15 at f5.6 and iso 200:



Rivers are dark.

[Eldo]

Sorry, was editing my post and did not see your reply.

Okay, the flash was definitely doing the illumination, so the synch speed is not an issue. But it sure looks like a motion-type blur, although more sort of an echo exposure.

Was it one of two flashes, and how were they (it) triggered?

[bklyn]

Do you make a habit of looking at the exif data for the photos that you feel turned out as you expected and the ones that did not?

[cmor]

Sorry, was editing my post and did not see your reply.

Okay, the flash was definitely doing the illumination, so the synch speed is not an issue. But it sure looks like a motion-type blur, although more sort of an echo exposure.

Was it one of two flashes, and how were they (it) triggered?

echo exposure?

3 flashes, 285hv's, triggered with alien bees cybersyncs

Do you make a habit of looking at the exif data for the photos that you feel turned out as you expected and the ones that did not?

I'll go flip through them. I was bumping the aperature around, And ending up slightly overexposing a few, I should have kept more near f8 for the series. I shot it over two days which makes it harder to nail down what went wrong. Heres an interesting series to show the ambient vs flash. I had it on continuous shooting so the second shot is all ambient. This is at f7.1, so only slightly darker. Straight from camera with a raw to jpeg conversion:

[cmor]

I realized the ones above are from two days later, although similar lighting. Heres one from the same day as my original post, at f7.1 and 1/200:

[dipstik]

I'm wondering if your 3 strobes are all firing at the same time?

If one of the units is slow to discharge the flash, it would explain why the rocks are sharp and the kayaker has a slight blur.

[Lonnie]

I'm wondering if your 3 strobes are all firing at the same time?

If one of the units is slow to discharge the flash, it would explain why the rocks are sharp and the kayaker has a slight blur.

I bet this is the answer.

[Eldo]

^ I am wondering the same thing, because it sure looks like a ghost image is causing the blur. (I tried PSing the close up of the kayaker using the Blur - Motion filter and could make zero improvement. Usually that filter can work some serious magic.)

Since you used radio slaves, then it can't be an echo flash. Those units have a spec'ed latency of only 1/4000 of a sec, so any timing difference between them should be miniscule. But as mentioned maybe one is malfunctioning?

Going back to the flash duration of the 285HVs at full power, I have read some tests that claim the light output actually stretches to more like 1/100 of a second because it takes time to build to a peak - which lasts about 1/1000, as per the rating. That might account for a blurred image.

[cmor]

^ I am wondering the same thing, because it sure looks like a ghost image is causing the blur. (I tried PSing the close up of the kayaker using the Blur - Motion filter and could make zero improvement. Usually that filter can work some serious magic.)

Since you used radio slaves, then it can't be an echo flash. Those units have a spec'ed latency of only 1/4000 of a sec, so any timing difference between them should be miniscule. But as mentioned maybe one is malfunctioning?

Going back to the flash duration of the 285HVs at full power, I have read some tests that claim the light output actually stretches to more like 1/100 of a second because it takes time to build to a peak - which lasts about 1/1000, as per the rating. That might account for a blurred image.

How do I test if all 3 firing at the same time? It would have to be off by only 1/500 or so....

I could probably see if the flash duration of one is off, i'll give it a go today.

This is kind of going the route of hardware malfunction, I'm more inclined to believe its user error, as I am usually the weakest link in the system. I would like to know whats wrong though before blowing more time on blurry shots

[cmor]

So all the flashes are syncing within 1/1000, I can shoot at them using a 1/1000 shutter speed and still get them in the bottom of the frame.

I think it might just be the flash duration on the 285's, playing around its fairly easy to induce blur into your shots...

EDIT: I noticed you said slow to discharge. So the cybersyncs are working fine, but maybe the discharge is long? It doesnt appear one of them is slower than the others, they all seem to induce the same amount of blur when testing fast moving objects, but I haven't formally tested that.

[dipstik]

So all the flashes are syncing within 1/1000, I can shoot at them using a 1/1000 shutter speed and still get them in the bottom of the frame.

I think it might just be the flash duration on the 285's, playing around its fairly easy to induce blur into your shots...

EDIT: I noticed you said slow to discharge. So the cybersyncs are working fine, but maybe the discharge is long? It doesnt appear one of them is slower than the others, they all seem to induce the same amount of blur when testing fast moving objects, but I haven't formally tested that.

So you're getting the blur even when you're only using 1 flash unit? Are the results similar for all levels of power?

[Eldo]

Discharging the flash just means triggering the flash.

I did a quick test with a 285HV and at full power it is surprisingly easy to get motion blur (tested by moving the camera while shooting a static object) but very difficult at lower power such as 1/4.

So maybe the conclusion is that the flash duration of those Vivitars at high power is not short enough to successfully freeze that kayaker shot. If that's the case, you need to try a setup that doesn't require full flash power, which means placing the flash closer, or using a larger aperture but without allowing ambient light to interfere. Of course neither of those solutions might be possible.

That or drop thousands on some dedicated flashes that can do high speed synch.