Am I nuts or my rebel can x sync at 1/320?

[DocFrankenstein]

I am confused.

When I was viewed this shot, I was dissapointed:
http://photo.klein-jensen.dk/public/Dia_Hair_Web.jpg (66kb file)

There's motion blur in it, at 1/125 sec. :confused: For some reason I remembered reading that rebel will sync at 200 with EX flashes and 125 with non EX.

So naturally, I kept Av=10 and Tv=125

But 5 minutes ago, I took out the Drebel and took a shot at 200... the frame was white... I took a shot at 250... 100% white... 320... 100% white...

Only at 400 did I get the bottom of the picture to be unexposed to the flash.

And I am using 1/16th (lowest power) on my vivitar. So that should give a burst of light which lasts 1/10000th of a sec or something like that.

I am sober BTW.

How is this possible?

[Bodog]

Doc, I've noticed the same thing. I've even gotten to 1/400, but it isn't consistent.

[slin100]

The sync speed is set conservatively for a comfortable margin of error.

[DocFrankenstein]

This was shot at 320
http://andrew4137.fotopic.net/p11776841.html

This at 400
http://andrew4137.fotopic.net/p11776842.html

Have u ever gotten "the shadow" at 320?

But what margin of error can there be?
The spring moves the shutter, so the speed of the curtain is the same.
The electronics are working the same way every time...

[Bodog]

Yes, Probably 1 out of 3. Steven is right, I'm sure. It's just a margin of error. When I first got the camera and was experimenting, I thought it was consistent, then took a series of my grandkids using 1/320 and up. Most were only half a picture. (the shadow isn't always apparent on the preview screen) Don't even consider using anything above 1/250 now. My flash is not an EX series by the way.

[DocFrankenstein]

I dunno... I took about 30 pics at 320 both landscape, and rotated plus minus ninety degrees.

All of them appear consistently exposed.

I just found out I lost quite a lot of portrait opportunities. :(

I'll do some more experimenting.

[Bodog]

Are you using the built in flash, or some other? I didn't think to try the built in. Never mind. I just tried the built in and the camera will set a TV less than 1/200 even in manual mode.

[DocFrankenstein]

Yeah... it's not the built in. Built in restricts you to 200.

Maybe the EX flashes waste some time while they communicate back and forth between lenses/camera/flash?

Scott Berger where are you? LOL :lol:

[Monito]

But what margin of error can there be?
The spring moves the shutter, so the speed of the curtain is the same.
The electronics are working the same way every time...

Spring constants are a statistical thing. When shutters are calibrated at the factory for timing accuracy (non-flash, 1/4000 sec to 30 sec), it would be difficult to simultaneously tweak their sync characteristics. So the manual gives a conservative setting. The manual is printed the same for all cameras shipped.

This thread is very interesting. It is worth knowing the max sync speed of one's camera. Thanks to the contributors who tested and posted images. I will check mine right now!

[Mark Kemp]

Some EX flashes have a h - high speed sync setting - lets you use any shutter speed at reduced power mainly for fill in with shallow dof shots. Were you using this perhaps?

[Monito]

Hmm, it seems I can only sync my 20D at 1/250. No matter what the setting, if the flash is going to be allowed to fire, the camera sets the shutter to 1/250. If I put on my 420EZ (not EX), then I also only get 1/250. I can't get the camera to go to any faster speed (can get slower speeds). Don't know how it would perform with a modern EX flash.

[ron chappel]

In the past i've noticed that my 300D syncs up to about 250th but not consistantly.I used a cheap add on flash to test it

One other thing worth thinking about is that the shutter speeds may be just plain inacurate and the flash sync speed could be right
i.e., it's saying it's syncing at 320 etc but it may actually be going alot slower

[DocFrankenstein]

One other thing worth thinking about is that the shutter speeds may be just plain inacurate and the flash sync speed could be right
i.e., it's saying it's syncing at 320 etc but it may actually be going alot slower
This is what I'm afraid about. If my shutter is fried, then I have a problem...

But it's highly unlikely that I have a bad shutter. Because I would probably be getting overexposed images due to one stop in light difference, and I'm not. :confused:

Hmm, it seems I can only sync my 20D at 1/250. No matter what the setting, if the flash is going to be allowed to fire, the camera sets the shutter to 1/250. If I put on my 420EZ (not EX), then I also only get 1/250. I can't get the camera to go to any faster speed (can get slower speeds). Don't know how it would perform with a modern EX flash.
If your 20D feels the flash, it's gonna foolproof the user and set it to the official sync speed for your camera. One way to bypass this would be to tape up all of the flashes contacts, except the middle one. But then the flash is fully manual.

Some EX flashes have a h - high speed sync setting - lets you use any shutter speed at reduced power mainly for fill in with shallow dof shots. Were you using this perhaps?
I highly doubt it. I used a vivitar 285 at the lowest power. (1/16) They are usually used to take pictures of water droplets and such... and to freeze the motion.

Can anybody try this with something fully manual like vivitar? Be careful not to fry your shutter. Use either "wein safe sync" or check the voltage not to exceed 6V on a good voltmeter or an oscillograph

Funny thing is that my rebel is a refurb. LOL Must've modified it a bit. :D