Flash Sync Speed
 

Hello there,

I read this article and I am confusing now http://www.kenrockwell.com/tech/syncspeed.htm

By the statement "Sync speed is the fastest shutter speed you can use with flash, period." My nikon d40 can fire a flash at 1/4000s. Does that mean my d40 Flash Sync Speed is 1/4000s?

TIA

Regards
Leigh

Wrong link, friend.

No. Your flash sync is 1/200. Anything faster than that will cause the flash to appear on only a portion of the image.

I should mention that the SB-800 and SB-600 flashes can do 'Auto FP high-speed sync', but only with Nikon's more pricey cameras.

Sorry about that. I updated the right one.

Hi Daniel,

I shot this photo http://www.smootharm.com/picture/nfp...002/272246.JPG 1/4000s using sunpak 5000 flash at 1/64 power settting IIRC. The flash distance to the subject was less than 10cm. The camera lens to the subject distance was less than 6cm. I can not find anything unusal in the image though the bug was only around 1mm in diameter in the image.

Regards
Leigh

Are you sure the flash illuminated the photo and not the sun? Take two pictures to be sure. Also, I recommend posting photos with the EXIF intact to provide people like me with additional information.

I am sure the light is from the flash and not the sun. Without the flash, the picture was just black and unfortunately I deleted the photos as I thought black photo was bad. ;-)

I just downloaded a viewer http://www.irfanview.com/ which I open the jpeg file I posted. I does show EXIF information for you ;-)

Regards
Leigh

I would stick with the fastest shutter speed sync for flash of the camera. The faster the better.

Which one 1/4000s or 1/500s?

Look in the manual, but likely it's 1/200 or 1/250.

A nikon firing a nikon system flash, or a canon firing a canon system flash can indeed fire far quicker than "sync" speed. BUT, that is the only way to do it. If you're using studio-type strobes, or any other brand of flash on the camera, stick to the specified speed in the manual (1/200???).

Now, this can be a bit misleading. You may think that with a speed of 1/200, you'll get crazy blur. You might, if the flash is not fully lighting your scene. But think of it this way - the amount of time your flash is "lit" is the amount of time the sensor sees light. That's how a shutter works - the amount of time its open is the amount of time it sees light. The flash duration itself effectively becomes the shutter speed. My Elinchroms fire at 1/2600 - meaning that no matter how long I leave the shutter open, the exposure of objects lit only with flash WILL NOT CHANGE. The effective "freezing" power of my flash will be equivalent to continuous light, and a shutter speed of 1/2600.

Now back to what was mentioned before - if you set the speed faster than the fastest safe sync speed, you MAY on occasion get lucky and have a properly exposed frame. MAYBE. More likely, a slice of your frame will look correct, and the rest will be black. Essentially you're trying to "catch" that 1/2600 flash burst somewhere while your shutter is open. The longer the shutter is open, the more likely you are to catch that burst. Flashy sync systems to external trigger are not terribly accurate, which explains the slow sync speeds, and why manufacturers can allow faster syncs with their own propreitary strobes. With a flash on the shoe, they can also calculate the exact length of wire and circuit trace between the sync signal in the camera and the trigger for the flash - meaning they can make it work consistently (as opposed to the external sync, which on low end cameras can vary by huge amounts even among the same model).

Sports illustrated (and ESPN mag) and other large sports photo depts. often set up multiple remote cameras and strobes during arena sporting events. To distract the crowd less, they only hang (usually) one set of lights, all sync'd together. Then all of the cameras are sync'd, and a master trigger can fire all at the same time, or only specific cameras. Regardless of how many of the cams fire, they all sync the same set of strobes. Thy often mix medium-format cameras (1/60 sync) with digitals (up to 1/500 sync). To allow this to happen, they use a fairly slow sync speed, but extremely powerful strobes turned down very low in order to speed up the flash burst. This has the effect of freezing action, even with long shutter durations.

So the moral of the story is: with enough light hitting the subject from strobes alone, and with strobes that fire short flash durations, the actual camera sync speed is mostly irrelevant. just make sure its slower or equal to the max "safe sync" speed of the camera.

The value is 1/500s

Reference: Sync Contact: X-contact only; flash synchronization at up to 1/500 sec.
http://www.nikonusa.com/template.php...roductNr=25420

The fastest shutter sync with a flash unit is 1/250. Every camera is different. My wife's Contax has a shutter speed of 1/6000 but the flash unit sync is only 1/200, from what I recall.

So the conclusion is if I can manage get full frame proper lighting, I can use any shutter speed I wish, right?

"The fastest shutter sync with a flash unit is 1/250." I meant to include "with my camera."

Regarding your last question: I don't know.

It has to do with the shutter in your camera, and it's capabilities, along with the flash.

Two curtains, one opens and reveals the image, the second closes to stop light. Most cameras sync at 1/250 max, because (1) it's a limitation of CMOS sensors, and (2) building a shutter system to allow flash sync above 1/250 would increase the price of the body considerably. As of late, many manufacturers began putting in a stop circuitry that'll just cut off any sync to the hot shoe above the stated sync speed, that goes for my Pentax K10D and *ist DL.

However, on my older Canon 1D, the stated sync speed is 1/500. Why?
Because it has an older "out dated" CCD sensor, and a top-of-the-line shutter build. It's also older, with nothing to stop me from firing the shutter above 1/500. I fire my older manual (Vivitar 285) flashes at 1/1600, no issues. When you gain shutter speed, the flash will not be able to hit the sensor long enough inbetween those two curtains, thus a portion of the image will be blacked out.

On the older D70's the shutter was partially electronic, which allowed you to sync the flash pretty high, I think around 1/500.

After taking so many macro shots, I think that I really love my d40 which allows me to take 1/4000s with external flash and no black out image.

Regards
Leigh

Sync speed can vary with same maker flash units for your camera.

On my Canon cameras, sync with studio strobes is 1/200th.

But if I use my Canon flash unit with high speed sync turned on, I can sync up into 1/2000 range as the camera and flash unit are made to work together.

It really depends on the subject and ambient light. Flash illumination falls off per inverse square law so background may not be sufficiently illuminated if too far relative to subject. Often you can choose a slow shutter speed to pick up better background exposure and use the flash exposure to freeze the subject.