2nd curtain sync .....

[cecilc]

Hello, all ...

I was trying this combination for high school football last Friday night:
Canon 10D
Sigma 120-300 2.8
Canon 550EX flash

I had the camera set for 2nd curtain sync (via one of the custom function settings) and I had the flash unit set for high speed sync. But in looking at the exif data after the game, this was the exif data:
File Name
CRW_8538.CRW
Camera Model
Canon EOS 10D
Shooting Date/Time
9/24/2004 9:36:40 PM
Shooting Mode
Manual Exposure
Tv( Shutter Speed )
1/250
Av( Aperture Value )
2.8
Metering Mode
Evaluative Metering
ISO Speed
800
Lens
120.0 - 300.0 mm
Focal Length
300.0 mm
Image Size
3072x2048
Image Quality
RAW
Flash
On
Flash Type
External E-TTL
Flash Exposure Compensation
0
Red-eye Reduction
Off
Shutter curtain sync
1st-curtain sync
White Balance Mode
Auto
AF Mode
AI Servo AF
Parameters Settings

I've highlighted the "Shutter curtain sync" data to ask this ....

What setting takes priority? The in-camera custom function or the flash setting? What I'm trying to accomplish is to have the high speed sync flash so that I can set my shutter speed at 250 (because without the high speed sync set on the flash unit, the 10D only syncs at 200), and to have the 2nd curtain sync so that IF anything "trails" it trails after the flash - not before.

I should also say that I didn't have any situation where 1st curtain vs. 2nd curtain would have been noticed .... so, in the final analysis, it probably wasn't a big deal. But seeing that exif data made me very curious .....

Can anyone offer any insight into this ....

And thanks in advance ....

[RichardtheSane]

Do you need to tell the flash to 2nd curtain sync?

I can remember off the top of my head, but you might...

[slin100]

The 2nd curtain sync setting in the Custom Functions is only for the built-in flash. You need to enable 2nd curtain sync directly on the 550EX. That implies that 2nd curtain and high speed sync are mutually exclusive.

[cecilc]

Do you need to tell the flash to 2nd curtain sync?

You can tell the flash unit to 2nd curtain sync ....

The "sync" command is a toggle between 2nd curtain sync and high speed sync - which means you can have one, but not both ....

I've done some reading since I made that original post, and I've deduced from my readings that:
1) If you've toggled the high speed sync "on" (on the 550EX) and can set your shutter speed above the "normal" sync speed of 200, then the "curtain" issue becomes a non-issue, since there's really no time for anything to "trail" either before or after the flash with higher shutter speeds.
2) Apparently the flash unit settings take priority over the in-camera custom function settings.
3) I was worried about nothing. :lol: But that's a good thing ......

Anyone with any further input on this? I'd still like to hear if anyone else has come across this situation and to know if my conclusions #'s 1 & 2 above are accurate .....

Edited section: Ahhh .... Steven got in while I was typing my response. I'm guessing that his post coincides with my conclusion #1 ....
Thanks, Steven, I appreciate the input.

[PacAce]

The 2nd curtain sync setting in the Custom Functions is only for the built-in flash. You need to enable 2nd curtain sync directly on the 550EX. That implies that 2nd curtain and high speed sync are mutually exclusive.

The highlighted statement is not entirely acurate. The 2nd curtain custom function can also be used for external EX series flashes that do not have a 2nd curtain switch built in, like the 420 EX.

[slin100]

Leo is correct. I don't have a 420EX.