Flash duration??

I'm confused;

With my old 1D in the studio, I could get shutter speeds up to 1/2000 with my AB800. Now with my 40D I can only go up to 1/250 before the image partially begins to turn black. This means I can't do water photography anymore.

Fill me in?

Flash duration is so short you don't need 1/2000th. The flash itself fires in 1/3200th of a second. That means as long as there's no ambient light at 1/250th, you'll have no problems.

huh?

The original 1D had an electronic shutter that allowed fast shutter speeds with flash. Today's Canon's with their CMOS sensors and mechanical shutters can only sync so fast.

What CDI is saying is that the shutter speed doesn't matter when flash is the only light source. After the flash turns off, it doesn't matter that the shutter is still open since the light level without the flash is insignificant.

Hmmm, thanks for explaining that.

So there is no way I can raise the shutter speed to do high speed flash photography anymore?

Crashoran wrote in post #4115249
Hmmm, thanks for explaining that.

So there is no way I can raise the shutter speed to do high speed flash photography anymore?

just turn your flash into the only light source and you're fine

either that or you can just set it on high speed flash mode, which is what i believed you meant anyway..

High Speed Sync is an option with Canon EX Speedlites, but not with your studio strobes.

As we've tried to explain, you can let the strobes freeze motion as long as they're the only light source.

Give it a try.

It was my only light source; I was in a dark room.

Then you are all set. If flash is your only light source, then the shutter speed does not matter! Read that over and over. You can use a 30 second shutter if you want.

100% of the exposure will occur in 1/3200s as the flash fires. The rest of the time the shutter is open there is no light and thus no exposure.

Try it. Set the camera to 1/250 and shoot the water drops. You should get the same result as with the 1D.

Hmm, I think I know what I did wrong. Thanks for the help

Now I need to learn about macro and extension tubes!

Cameras with a focal plane shutter have a "maximum sync speed" which cannot be exceeded when using studio flash units or other flash that is not able to "communicate" with the camera. The maximum sync speed is a function of the shutter design. There's no getting around this. The limitation is because of the design and operation of focal plane shutters.

Focal plane shutters are used in all Canon SLR cameras. Focal plane shutters have two blades or two curtains, depending on their design. At lower shutter speeds one shutter element (blade or curtain, depending on the design) will go completely across the film/sensor space, uncovering it completely and allowing light coming through the lens to impact the entire surface of the film or sensor. After the first shutter element has moved completely across the film/sensor space, then the second shutter element will start to move, again covering the film/sensor space and ending the exposure. The timing is based on the selected shutter speed.

As you go faster and faster with the shutter speed selection, there is a point reached where the shutter elements cannot travel fast enough to fully expose the film/sensor and then start to close it off. At any faster shutter speed, the second shutter element will start to move before the first has completely uncovered the film/sensor. Thus, a slit - of varying width depending on the selected shutter speed - travels across the film/sensor space.

You cannot use an electronic flash - with its very fast timing - when the shutter speed is so fast that only a portion of the film/sensor is exposed at any one time. The "max sync speed" is the fastest shutter speed that has the film/sensor totally exposed to light coming through the lens.

The ability for some Canon Speedlites to operate in a "high speed sync" mode is based on a series of flash pulses emanating from the Speedlight over longer than normal flash pulse periods. You will get less effective light from the flash at any point in time, but it does allow for some creative flexibility in using the flash.