Under exposed with the 580EX

papathree wrote in post #2772086
Yesterday I shot a wedding with my 5D and had a 580EX cabled from the hot shoe to a Custom Bracket. I used the 24-105 IS 4 Flash .I shot the flash in ETTL and the camera in Manual
F8 1/60 sec. I has the camera set for 400 speed film.
I also had the flash power supplied with a Battery 1+
The problem I had was most of the photo's were under exposed.
It seemed that when I had the lens zoomed out to 35mm and the flash said 35mm I did not get as good of light exposure as I should have. I was told this flash will do as good as my Quantum T4D, but I am now wondering if that
was true.
I would appreciate any suggestions or tips you can give me to help eliviate this problem
THanks
Ron

Do a text search and find threads on Canon ETTL and underexposure

The histogram is your best friend to ensure correct exposure. Good luck (better luck) in the future.

bieber wrote in post #2776533
...shutter speed doesn't affect flash exposure...

So I guess sync speed is meaningless? In my experience, if I'm using flash I don't go over 1/250th as my flash distance drops too much. The flash takes time to discharge, reflect and fill the sensor enough for the measured burst. Let it do as such.

Go set your camera to say 1/8000th and see how far that flash throws.

Back on topic: A 5D and a 580EX will shoot a wedding no problem. I've done it without incident.

Something isn't right. Either your camera and/or flash are improperly set/manfunctioning or you haven't spent enough time with the new setup to be risking weddings on them. Find which one it is and adjust accordingly.

cosworth wrote in post #2778848
So I guess sync speed is meaningless? In my experience, if I'm using flash I don't go over 1/250th as my flash distance drops too much. The flash takes time to discharge, reflect and fill the sensor enough for the measured burst. Let it do as such.

Go set your camera to say 1/8000th and see how far that flash throws.

Back on topic: A 5D and a 580EX will shoot a wedding no problem. I've done it without incident.

Something isn't right. Either your camera and/or flash are improperly set/manfunctioning or you haven't spent enough time with the new setup to be risking weddings on them. Find which one it is and adjust accordingly.

Synch speed is far from 'meaningless'. Above the synch speed (e.g.1/500), the flash goes into HSS mode (if enabled) and the light output from the flash has to be stretched so that light is output during the interval while the slit that forms the shutter moves across the sensor (faster than if at synch speed, where entire shutter exposes the sensor all at once).

Shutter speed, when the flash contributes ALL of the light to the scene, is meaningless since the flash output is normally a very brief duration (e.g. 1/1000), so having the shutter open longer contributes nothing to illumination of the main subject.

When the lights in the background are reasonable, the shutter speed can be slowed to the point where it permits the ambient light to be recorded; the flash still illuminates the main subject, but the ambient light illuminates the surroundings.

J Rabin and Wilt have provided good info so far. Here's my 2 cents:

1) Checking your histogram is something to do periodically, when you first begin and when conditions change. You shouldn't need to do it after every shot. This won't slow you down, and can prevent one bad shot from becoming hundreds of bad shots.
2) When using E-TTL flash as your primary light source (I know Jack, it's still "fill" technically speaking), switching custom function 14 to Average flash metering will result in more consistent exposure.
3) Setting your FEC at +2/3 is generally regarded as the "default" setting when using E-TTL flash as the primary light. E-TTL seems to be improperly calibrated, for reasons unexplained.
4) People who shoot weddings with new equipment and don't practice first to go through this learning curve before photographing the most important day in someone's life shouldn't charge very much.

Wilt wrote in post #2778956
Synch speed is far from 'meaningless'.

I was being facetious.

Your flash won't be doing much for you at f/11 and 1/4000th I was trying to say.

That being said, either the equipment was hooped or he didn't know how to use it. Determine which one and the OP is covered for the next wedding..

Collin85 wrote in post #2776700
He might have been talking about background exposure (which depends on ambience light) rather than the foreground subjects.

Thank you. Yes he was talking about BG exposure. A hotshoe flash like a 580 EX can usually pound out enough light on foreground subject, but that's different than illuminating a scene, which us QFlash users get used to.

cosworth wrote in post #2779428
I was being facetious.

Your flash won't be doing much for you at f/11 and 1/4000th I was trying to say.

That being said, either the equipment was hooped or he didn't know how to use it. Determine which one and the OP is covered for the next wedding..

Sorry, didn't notice your tongue planted in your cheek!

papathree wrote in post #2776519
So Jack, you are saying that for my weddings...better off to use my T4D...rather than...580EX.

No. Not necessarily. The Canon flash with E-TTL is wonderfully lightweight, convenient, fast easy, etc. Has lots of uses. Works really well - in MODERATE - lower light once you learn to ride FEC.
But, it is far from output of QFlash. When light is low, in a big dark hall, and you were used to getting successful QF exposures, no hotshoe flash can do that. At least one hotshoe Canon EX over the camera can't do that. Multiple wireless can.

What I am saying is Canon 580EX over the camera as fill and QF you are close to having the best of both worlds if you upgrade to T5-d-R and get a QNexus receiver.

I am also saying maybe you were used to the exposure tolerance shooting negative print film, which does not exist in digital photography (which behaves like transparencies).

Oh, welcome to POTN. Jack