Strobe sync @ 1/400: Pushing the limits.

bigrig wrote in post #7531019
So what determines how much shutter is shown in the frame, the response speed of the RF trigger and flash?

I've got a 40D and I'm playing around with a cheap RF trigger and flash I got from DealExtreme. My 1/250 shots look like your 1/640 shot! Most of them...some are fine. Hmm.

Matt

Thats most likely your trigger method.

I can get a perfect 1/320 with a cord (or cybersyncs) on my 40D and just a smidge or shutter in the camera on 1/400.

Speed is one of the reasons I just went ahead and got cybersyncs instead of radiopopper JRs. The cybersyncs have been out awhile and tested and consistently are very fast. I cant tell the difference in a shot with a cord vs cybersync at 1/400.

A new day is upon us the new Pocket Wizards Mini / Flex gives you

over x-sync right out of the box

PhotosGuy wrote in post #7547244
Older mechanical shutters had the "feature" of gradually slowing the speed down over time, starting with the faster speeds. Then they would need cleaning & recalibrating.
Do you know if that 1/320 second indicated as 1/400 second will remain constant over time now?

Note that I am not saying that your shutter speed is not 1/400 second. It might be that, but it could also be something else labeled as 1/400 second. And, being something other than the indicate speed would not be all that odd.

All of the Canon DSLR cameras have mechanical shutters that are not all that different from shutters in cameras 20 years ago (possibly longer).

So, I have no reason to have expectations of these shutters any different than I would have had 20 years ago.

In general the accuracy of the shutter mechanism is far less precise that most camera users assume, even with very high quality cameras.

I see all sorts of discussion about 1/10 of a stop accuracy in a meter, when the inaccuracy of almost any camera's shutter using the meters prescribed setting would often be off far more than 1/10 of a stop.

Enjoy! Lon

Well said Lon. My 40D syncs at 1/320 of a second with my AB800s -- I have long suspected thats because my 1/320th of a second is someone elses 1/250th......

i agree with jbergdoll it's not necessarily the shutter that is freezing the motion so much as it is the duration of the flash. the faster the flash duration the more motion gets frozen. but this is only true if you are exposing for the flash and not for the ambient light, in which case your flash either needs to be relatively close to the subject or zoomed in.