1 Ds MkII flash sync with Speedotron strobes

I'm starting to notice a dark area on one side of the frame when shooting my 1Ds MkII in manual mode at

1/250s at around f/16 with Speedotron strobes. I use Pocket Wizards to fire the strobes. Attached is a

sample of the problem.

<p>

Am I misunderstanding the X-sync speed of the 1Ds MkII?

<p>

The thing is I've been shooting at 1/250s for a while and never saw this before - and I'm wondering if my

shutter is having problems.<div></div>

How old are the strobes?

 

Older strobes have a sync voltage higher than 6v. If this is the case and you were not using a Safe sync voltage regulator the X-Sync connector in your camera may be damaged.

I'd put it rather that you are misunderstanding the rise time and flash duration from the Speedotrons. Canon's flash sync spec is relative to the duration from its own flashes, which is shorter than studio strobes. If you think about it, each shutter curtain has to cross the sensor, on average giving exposure of half the travel time (so the ambient exposure contribution totals the travel time of one curtain when the curtains are moving). The remainder of the ambient exposure comes from the period that the shutter curtains are completely open, which will be rather shorter than the nominal shutter speed. Flash durations greater than 1/500th will almost certainly be too long. Use a slower shutter speed with studio strobes.

I find the same thing with a 20D and 1dsmk2 when using studio strobes. It pays to do a quick test and find the shutter speed where illumination is completely even. 1/125 to 180 is usually fine, but always check.

 

JJ

Mr. Benton is entirely mistaken, the 1dsII sync circuit is rated for 250v.

 

Mark pretty much has it nailed, although I'll mention that the Pocket Wizards add a small

amount of delay too. But even 1/200th will likely work

I myself thought 250v was the limit.

 

However, I'm hearing that camera's like the 20D are 9 volts. The 250v rating is the max voltage input to the strobe system as some older are as high as 350v battery supply system.

 

I realize we are talking 1d's here, but just thought I'd share...

 

-Mario

From the manual(I do not own a 1DsMII so I had to look it up).

 

The Flash Sync for studio strobes is 1/125, and it also says that the camera should not be connected to units using 250V or higher.

 

So it would seem 249V is fine but not 250V?

 

The info is on page 100.

<cite>However, I'm hearing that camera's like the 20D are 9 volts.</cite>

 

<p>The 20D, as with many other recent EOS bodies, is good up to 250V, both for the hot shoe and for the PC.</p>

Argh... yeah, yeah, yeah... I need to curl up and re-read my manual - didn't mean to waste

people's time... Sorry for the lameness. But thanks for the responses - I will start re-reading

tonight...