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DPChallenge Forums >> Hardware and Software >> Splash Pictures/Sync Speed?
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06/07/2007 11:01:51 PM · #1
I just tried shooting some splash pictures, where you drop the fruit into a tank of water and take a picture. Anyways, when shooting at my sync speed of 1/200, it barely stops the action and there is a ton of blur. How do pictures like this - 107969.jpg - shoot at 1/2000? I'm using dyna light flash's. When I shoot over 1/200, it blackens the bottom part of the pictue becuase the curtain is too fast...

Any advice?
06/07/2007 11:03:40 PM · #2
try lots and lots and lots of light and no strobe or flashes and then you can increase your speed.
06/07/2007 11:08:14 PM · #3
Speedlights like the Canon or Nikon flash guns will do a better job than the dyna lights too, as the flash burst are faster.

If you are using flash try to bring ambient lighting to a bare minimum.
06/07/2007 11:09:19 PM · #4
Originally posted by fotomann_forever:

Speedlights like the Canon or Nikon flash guns will do a better job than the dyna lights too, as the flash burst are faster.

If you are using flash try to bring ambient lighting to a bare minimum.


this is true. a dark room helps
10/07/2007 11:40:41 PM · #5
I just did some today and I had the same problem! It is so frustrating, i worked in a completely dark room too... :(
10/07/2007 11:52:23 PM · #6
With little to no ambient light ... the actual exposure time is the speed of your flash (i.e. how long it takes the strobe to go from zero output to full output and back). Some units are faster than others. Alien Bees, I believe, are pretty fast. Most studio strobes are not so fast.

So your actual exposure limit is the speed of the strobe. If, with no ambient light, you are still seeing some blur, then your strobe isn't fast enough.

I don't know if you saw another thread posted earlier this week about fast glass... but I discovered that, in full sunlight, my camera simply is NOT fast enough to shoot wide open at f/1.2 (it has a max of 1/8000th of a second). I was trying out the 85mm 1.2L lens, and at ISO 100 using f/1.2 it would have required a shutter speed faster than 1/20,000 of a second to get proper exposure in broad daylight.

So... another solution would be to use a very fast aperture (2.8 or less) and lots of light. Then you can set your shutter speed very high.


10/07/2007 11:54:07 PM · #7
I don't know about the flash you are using, but the canon flashes offer a high speed synch mode that will solve that problem.
10/08/2007 12:11:03 AM · #8
Originally posted by jmsetzler:

I don't know about the flash you are using, but the canon flashes offer a high speed synch mode that will solve that problem.


Yes ... and no.

High speed sync works by SLOWING DOWN the flash ... generally by "pulsing" the light repeatedly. The flash exposure is actually LONGER when in High Speed sync mode than normal.

So, while it is true that you can use higher shutter speeds. All you're really doing "keeping the light going" long enough for both the first and second curtains to travel all the way across the sensor.

But, it does sound like an interesting experiment! Which is shorter? The speed of the normal flash? Or a fast shutter speed while in high speed sync mode? I don't know the answer.
10/08/2007 12:29:49 AM · #9
Here's something to think about...

Your flash sync speed is the shortest amount of time during which BOTH curtains (first and second) can be open at the same time, allowing for full exposure to all parts of the sensor at once.

So... if you have a flash sync speed of 1/250th, and you shoot at 1/250th of a second, then that means the first curtain will have traveled all the way across the sensor before the second curtain begins to close. But if you shoot anything faster than that, then the second curtain will begin to close BEFORE the first curtain has finished opening.

That means, for example, that at 1/8000th of a second, the 2nd curtain begins to close just 1/8000th of a second after the first curtain has opened, creating only a tiny "slit" of light as both curtains travel across the sensor. (meaning only about 3% of the sensor will be exposed at any given time).

So basically, flash sync speed is the MAXIMUM speed at which the curtains cross the shutter. Anything shorter than sync speed is "emulated" by exposing less and less of the shutter at any given speed.

So here's where I'm going with this...

If your subject is truly moving fast enough that you need a faster shutter speed than 1/250th of a second, then even at the higher speeds, there is the potential for MOTION BLUR to occur! Because the subject CONTINUES to move, even as only a "slit" of it is captured on the sensor at any given moment!

As an example... I'm going to pull some images from another internet site and then let you read more about it there:

Here is a stationary disk, capable of rotating at 40,000rpm:

turnedoff.jpg

This is what that disk looks like shooting at 1/4000th of a second:

s4000.jpg

Notice the uneven motion blur! Here is that same disk shot using ONLY a flash with the shutter speed set to 1/250th of a second:

flash.jpg

Two things to note here: 1) the flash is obviously faster than than the shutter speed, and 2) fast shutter speeds don't freeze the entire image at the moment of exposure.

Read the original article here.


10/08/2007 12:43:07 AM · #10
here is my freestudy entry.

587487.jpg

shutter at 1/2 second, iso 100, and aperature at f8

the motion stopped because the light
flash was so short.
10/08/2007 12:43:45 AM · #11
Thanks David - that was extremely helpful!
10/08/2007 01:03:42 AM · #12
There was a little bit of light in the room and I didn't think it would make a difference, but I guess it does. I will try a perfectly black room and see what happens, this is my fav shot from it, took quite a bit of sharpening:
597026.jpg
10/08/2007 01:31:35 AM · #13
Originally posted by dwterry:

Here's something to think about...



Excellent post :) That demonstration does an excellent job of describing what happens with the flash sync.

The flash that fires in a 1/250" shutter would be adequate to freeze motion IF the subject is in the dark. Setting up those splash photos can be done at a 1" shutter speed if it's done in a dark room. If the only light exposing the image is from the strobe, the duration of that strobe will be the effective shutter speed of the image.

That second image in the demonstration supports this point nicely. If there is additional light in the scene that can be exposed, it's going to lengthen the actual exposure...
10/08/2007 01:41:45 AM · #14
Originally posted by dwterry:

With little to no ambient light ... the actual exposure time is the speed of your flash (i.e. how long it takes the strobe to go from zero output to full output and back). Some units are faster than others. Alien Bees, I believe, are pretty fast. Most studio strobes are not so fast.

So your actual exposure limit is the speed of the strobe. If, with no ambient light, you are still seeing some blur, then your strobe isn't fast enough.

I don't know if you saw another thread posted earlier this week about fast glass... but I discovered that, in full sunlight, my camera simply is NOT fast enough to shoot wide open at f/1.2 (it has a max of 1/8000th of a second). I was trying out the 85mm 1.2L lens, and at ISO 100 using f/1.2 it would have required a shutter speed faster than 1/20,000 of a second to get proper exposure in broad daylight.

So... another solution would be to use a very fast aperture (2.8 or less) and lots of light. Then you can set your shutter speed very high.


Lots of flash and small aperture may solve the problem by reducing the ambient light for the splash pics. If the flash is strong enough, it will mask the little bit of ambient light getting thru the lens at small aperture and medium shutter speed. I use the technique for macro a lot in order to reduce the background to near black. I would guess that the best of the splash images are done with a ring light.

DW, If you want to shoot at f 1.2 outdoors in sunlight, you need to have a neutral density filter to reduce the light coming thru the lens. A polarizer is good for a stop or two in a pinch.
10/08/2007 01:48:29 AM · #15
Here is what a did....... details on the photo

375610.jpg
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