EOS 350D High-Speed Flash Sync

Does anyone know to what maximum speed the EOS 350D flash syncs with

an external speedlite? i cannot seem to be able to find it in the

manual. I am planning to use the speedlite 420EX over the weekend

for some concert shoots.

 

thx

<A HREF="http://photonotes.org/cgi-bin/camera-flash-lookup.pl?

cameraType=eos350d&flashType=canon420ex">http://photonotes.org/cgi-bin/camera-

flash-lookup.pl?cameraType=eos350d&flashType=canon420ex</A>

<P>

Also, search for "X-sync" in the manual.

thx for posting NK guy, it says on the website 1/200, is that possible? i know that is the sync speed with the normal flash...

Review page 66 (Flash Photography) and 164 (Specs) in your manual (the table of contents

is amazing!). Maximun normal X-sync shutter speed is clearly delineated in both sections.

The test will be on Monday and will comprise 50% of your grade.

 

Of course, focal plane (pulsed or high speed sync) works at any speed albeit with greatly

reduced power.

ok thx for your answers and clearing this up...the 350D has an X-sync speed of 1/200 which is crap cause if you want to take macro shots of running water you will only get blurs (which is what i get with my normal flash...)

 

or am i making some silly mistake here?

I thought the 420EX can sync at any speed if set to the hi speed mode?

Are you making a silly mistake? You are if you think a high sync speed matters when illuminating a scene solely with flash. It doesn't matter if the shutter is open for 1/500 or 10 seconds, if the vast majority of light comes from the flash the net result will be the same.

 

If you are using the flash as fill, then you do want the highest sync speed you can get.

It's not clear to me what you think you are trying to achieve. Used at 100 ISO and with a sufficiently narrow aperture, your image will almost entirely be lit by flash if the subject is within range. The effective speed from the point of view of freezing motion is then the flash duration - i.e. 1/1000th or less, regardless of the shutter speed set so long as it is 1/200th or slower. If you are looking for some fill in daylight conditions, then the FP (high speed sync) mode will allow any shutter speed the camera can manage - i.e. up to 1/4000th. However, you do lose range when shooting in this mode, and higher ISO doesn't help because you have to shorten the exposure to balance the ambient light, which reduces the flash exposure too - the flash effectively is working as a continuous floodlight, spreading its power output over the whole period the shutter curtains are travelling across the sensor. Since shutter speeds higher than max X sync are achieved by progressively narrowing the gap between the two curtains as speed increases, you get less exposure from all sources of illumination as shutter speed is raised. At max X sync and below, the whole sensor is exposed when the flash fires, so none of its output is wasted.

ok what i'm trying to do is freeze a drop of water in mid-air using flash as my kitchen is not lit well. If you look at my gallery you will see many of these drops perfectly frozen with my sony dsc-f828, at a shutter speed of about 1/1000 iso 200.

When trying a 1/1000 shutter speed (iso 200-800) with the EOS 350D and the speedlite 420EX, the drops are not frozen, there are traces of them all over the place.

What am i doing wrong?

Try changing the the shutter speed down to 1/200 and stop down so that the exposure meter reads -2, then go down one more full stop. Be sure to turn off the high-speed synch mode on your flash and then see what the results look like.

sounds like a plan, thank you! will let you know of results

As has been mentioned, High Speed Sync is not what you want, as it actually forces the flash to be lit for a <i>longer</i> period of time than in normal flash sync. You want a <i>short flash duration</i> to freeze the water drops, not a faster shutter speed.<p>The problem may be that the 420EX is more powerful and has longer flash durations than your Sony's flash.<p>The approach I would try is to use low/no ambient light, some high ISO, a regular sync shutter speed, and a wide open aperture in order to require a shorter, less powerful, water-drop-freezing flash burst from the flash.

Another thought is that the Sony is a shutterless camera (i.e., full time LCD preview). If that is so (and I think it is), then there's no real "shutter speed", just how long the lens is stopped down and the image is read from the sensor. The Sony then can achieve X flash sync at high shutter speeds because there's no shutter curtains to move.

 

You'll get the frozen droplet with the Sony not because of the high shutter speed, but the very brief, single pulse of flash illumination. The Sony doesn't need to do FP flash pulses at high shutter speeds. It can essentially do "X" type sync because the whole sensor is always in view.

 

On the 350D with its focal plane shutter, at speeds below or equal to the X sync speed, the whole shutter opens. That is, the opening curtain completely uncovers the sensor, the flash fires, then the closing curtain covers the sensor. Above X speed, the closing curtain "chases" the opening curtain across the focal plane, exposing a slit of the sensor at a time. As shutter speed increases, the slit gets narrower and narrower. In order to do high-speed flash sync, the flash gun actually fires many small pulses of light as the shutter moves. These pulses effectively illuminate the entire sensor as the slit travels across.

 

In the your case, though, the droplet is moving relative to each flash pulse, so in effect you're getting multiple exposures of the drop of water as it falls, creating a motion blur effect.

 

As others have already posted, if the you drop the shutter speed to X or below (1/200 in this case - turn off FP mode), the flash will fire a single, brief pulse and freeze the action of the water drop. Instead of multiple pulses, you'll have one very brief pulse. What the you need to keep in mind is that even though the shutter is open for a comparatively long time, the flash pulse is so brief that it freezes the motion.

 

When the flash is your only (or primary) source of light, its characteristics take over in terms of stop action effects. Even though the shutter is open for a relatively long 1/200 (or even longer), the flash pulse is cut off by the auto-exposure system once enough exposure is given. That flash pulse could be as brief as 1/10000sec - more than fast enough to stop the water droplet in its tracks. Even a "full power" flash is usually on the order to 1/1000sec. Flash guns do not typically vary the actual light output from the tube, instead they vary the length of the pulse to control exposure.

Now that we know what you are trying to do, I can confirm that Paul's approach is the right one. Since flash duration is linked to power, the wide aperture will shorten the duration required (shortest duration might be as little as 1/30,0000th). Work in M mode, so that you can control the impact of ambient light as well. You will probably also want to set focus manually. You may also want to try different levels of FEC to achieve the effect you want. You might be interested in this link:

 

http://www.hiviz.com/

 

Of course, these techniques have little in common with those for shooting at a concert, where a fast lens that allows you to use little or no flash to capture the atmosphere of the lighting is probably preferable.