high speed sync question

[24nofear]

Just trying to figure things out and still need help.

Does anybody use it?
Do you leave flash at full power?
do you use fill flash for group photos?

[Curtis N]

It is a specialized technique, valuable only for certain situations.

If you're using E-TTL, then no adjustment in FEC should be required. If you're using manual flash, you will need to crank up the power a couple stops since HSS is inherently inefficient. Keep an eye on the distance scale on the back of the flash.

More info here:
http://photography-on-the.net/forum/showthread.php?t=208520

[24nofear]

hey thanks a lot. I read that last night and I guess I should read it again.
now say I am at sync speed or lower then should I worry about FEC?
Just thinking again manual 1/1 is that the same power out put as 0 or +3? or am I way off on what I am thinking?

[Curtis N]

Manual 1/1 is full power. Manual flash is for situations where you have a chance to measure the light at the distance you'll be shooting (such as with a flash meter). It's more of a specialized technique and used mostly with off-camera flash.

When you are using E-TTL flash metering, FEC is used to account for subjects of varying luminance (white wedding gown vs. black tux) and to adjust the flash exposure according to your goals. FEC is the way to control the flash exposure with E-TTL, whether you are using normal flash and high speed sync.

[Meaty0]

Manual 1/1 is full power. Manual flash is for situations where you have a chance to measure the light at the distance you'll be shooting (such as with a flash meter). It's more of a specialized technique and used mostly with off-camera flash.

When you are using E-TTL flash metering, FEC is used to account for subjects of varying luminance (white wedding gown vs. black tux) and to adjust the flash exposure according to your goals. FEC is the way to control the flash exposure with E-TTL, whether you are using normal flash and high speed sync.

Hope you guys don't mind me chiming in here. 24nofear didn't say whether he/she was referring to fill flash or "flash as the main light source".

Curtis. Say you're shooting a Bride and Groom outdoors in light shade and you want to use Fill Flash. Also say you're shooting 1/250 (synch speed) with a 580ex set to E-TTL. If you are using Av mode, the camera supposedly adjusts the fill flash automatically (and usually gets it wrong for me:(). You would adjust the output using FEC then wouldn't you??

Just for the record...through experimentation, I have found I have to shoot about -1 FEC in light shade and about +2 FEC in our full sun to get correct exposure with fill.

[Curtis N]

Curtis. Say you're shooting a Bride and Groom outdoors in light shade and you want to use Fill Flash. Also say you're shooting 1/250 (synch speed) with a 580ex set to E-TTL. If you are using Av mode, the camera supposedly adjusts the fill flash automatically (and usually gets it wrong for me:(). You would adjust the output using FEC then wouldn't you??Yes.Just for the record...through experimentation, I have found I have to shoot about -1 FEC in light shade and about +2 FEC in our full sun to get correct exposure with fill.Keep experimenting. The difference shouldn't be that great.

[Meaty0]

Yes.Keep experimenting. The difference shouldn't be that great.

I'm ALWAYS experimenting:D

Curtis, what FEC settings do you usually find yourself using for the situations mentioned above?

[Curtis N]

Curtis, what FEC settings do you usually find yourself using for the situations mentioned above?Usually between 0 and -2/3. The determing factor is usually subject luminance (white clothing or highly reflective stuff that tends to make E-TTL expose darker).

[S-Man]

This is very informative. I tried to use High Speed synch today without success. It was a bright sunny day and my nephew had field day at his school. I had better results in Av mode, with the flash in manual mode set to 1/4-1/2 depending on shade. F8 and up due to the bright sunlight. I tried FP mode and the pictures came out almost black. When I press the FP mode button on the 430, does it automatically set the shutter to like 1/4000th or something ridiculous? ISO was at 100-200. What say you?
P.S. Thanks for all the info!

[Curtis N]

I tried FP mode and the pictures came out almost black.Please read my signature. ;)
If you post a sample with EXIF, I'm pretty sure we could figure out what went wrong.

Wild guess: You cranked up the shutter speed without a corresponding adjustment to the aperture. This underexposed the ambient light terribly. At the distance you were shooting from, the flash was not powerful enough to overcome this.When I press the FP mode button on the 430, does it automatically set the shutter to like 1/4000th or something ridiculous?No. All it does is allow you to use fast shutter speeds if you decide to, or if the ambient light requires it in Av mode. If your shutter speed is at X-sync speed or slower, having your flash in FP mode does nothing.

[S-Man]

Thanks. I'll read it. I was in Av mode and it did set the shutter to 1/4000s. Check this out.
I thought it weird.
http://lh6.ggpht.com/S.Man2381/SCOQuvaIfrI/AAAAAAAADNM/XozkraDfw6c/s400/IMG_3802.JPG
Filename: IMG_3802.JPG
Camera: Canon
Model: Canon EOS DIGITAL REBEL XTi
ISO: 100
Exposure: 1/4000 sec
Aperture: f/8.0
Focal Length: 28mm
Flash Used: Yes

[Meaty0]

Whoa! Looks like the flash went off when the shutter had already closed. Does the 430 have a High Speed flash synchro setting? I can't imagine why the Av mode would meter a shot that way...even if flash is in FP mode. I thought most cameras over-ride the setting if you exceed the flash synch speed.

[S-Man]

That's what was so weird. I could understand if it was in P mode or something, but in Av mode, I didn't know that pressing the High-SPeed synch button on the 430 would alter the shutter speed. I have to do more reading and play with it some more to figure this thing out.
Given the distances, it wouldn't have helped anyway in this circumstance.

[Meaty0]

That's what was so weird. I could understand if it was in P mode or something, but in Av mode, I didn't know that pressing the High-SPeed synch button on the 430 would alter the shutter speed. I have to do more reading and play with it some more to figure this thing out.
Given the distances, it wouldn't have helped anyway in this circumstance.

The high speed synch button doesn't alter the shutter speed, it allows the flash to synch with speeds higher than "normal" synch speed (1/125?) by staggering the flash output over a longer duration. I think that's how it works anyway. Still don't see how it would mess up the shot.

Do you remember what metering mode you were using?

[PacAce]

This is very informative. I tried to use High Speed synch today without success. It was a bright sunny day and my nephew had field day at his school. I had better results in Av mode, with the flash in manual mode set to 1/4-1/2 depending on shade. F8 and up due to the bright sunlight. I tried FP mode and the pictures came out almost black. When I press the FP mode button on the 430, does it automatically set the shutter to like 1/4000th or something ridiculous? ISO was at 100-200. What say you?
P.S. Thanks for all the info!
Your problem is caused by you setting the flash in manual mode in HSS mode with the camera in Av mode. When the flash is in normal mode, the camera will limit the shutter speed to 1/250 of a second but when you set it to HSS mode, the camera will set the shutter speed to whatever the fastest shutter speed is for the camera. Don't ask why but that's how Canon set it up when using an EX flash in manual mode and Av mode. Get the flash out of manual mode and you'll be fine. Or change the camera to M mode, too, if you want the flash to stay in manual mode.

[tdodd]

See the second row of photos in this post. HSS kicked in (I'd already set it on but it has no effect at the synch speed or slower) as I increased the shutter speed beyond the synch speed. There was no complicated manual adjustment of the flash required. I just left it in ETTL-II mode and the only thing I altered was shutter speed to adjust the background exposure....

http://photography-on-the.net/forum/showpost.php?p=5486539&postcount=14