580EX Let me down... any ideas why?

I covered a championship soccer game over the weekend, and right after the game there was an awards ceremony that I wanted to get some shots of. I threw on a 580EX because the lighting had really dropped off. I took a couple of test shots of both teams to get things dialed in... shot with 1DMk2N and 24-105mm f/4 L IS. I shot Aperture Priority and ISO1600, 1/250s, f/4. I took a couple of test shots of one team (see image 1), then turned my attention to team 2 (see second image). The teams were side by side and I basically just took a few steps over to get in front of the second team, and fired. The first shot of the second team, and all subsequent shots taken with flash were completely blown out. I checked the EXIF and it was the same on both. I ended up turning the flash off and shooting without it. Any idea what went wrong here?

1.

You were shooting Av, that’s what was wrong.

For the given lighting conditions, you should have shot Manual, ISO 400 and everything else the same.
Adjusted FEC as necessary.

In this case you used flash as a fill-in source of light which was not enough for the correct exposure..

Hermeto wrote in post #2224713
You were shooting Av, that’s what was wrong.

Come on. That doesn't begin to explain the blow-out of shot #2 above, and there is nothing inherently wrong with Av mode for fill flash. Of course, if you use the custom function which forces the shutter speed to x-sync with flash, then it's really manual mode.

A couple ideas:
1) You somehow inadvertently swithced the flash to manual.
2) You somehow inadvertently cranked up the FEC.
3) You somehow inadvertently hit the FEL button with the spot metering circle aimed at the distant trees.

I know all of these are long shots, and the EXIF might eliminate all of them. I would like to see the EXIF for shot #2.

Shot #1 doesn't appear to have received much flash at all.

I can see EXIF for both of them and they are the same..

For the rest I admit I might be wrong, but it looks like the first one was shot with the flash not completely recharged, while the second received the full blast on the top of ISO 1600.

We can debate whether to shoot M or Av, but that has nothing to do with my question. If you notice, the sky was exposed fine in both shots... so my ambient settings were fine. Whether in M or Av, the 580EX is supposed to meter for fill. So that shouldn't have effected this.

I took several shots that were fine of the first team, and literally 5 seconds transpired before I took a half dozen shots of the second team that were all blown. The flash was on ETTL in both cases, so no manual. No FEC was set on the flash. I am using the * button on the back for focus, and I'm reasonably sure I hit no other buttons... I had been shooting for 2 hours prior to this happening (albeit without flash). When I got the blow out, I tried a couple of settings changes on the camera... tried manual and same thing... tried P and it worked, but gave me the very dark background... so I just turned the flash off and shot with ambient light... which wasn't that bad.

Looking at the blown shot, it looks like it completely missed the team in the foreground and lit up the team standing out in the middle of the field. The images are uncropped, and it seems to me that the sitting team is what should have been picked up... but is there something about them sitting that would have effected this?

EXIF from first image...

File: - U:\Pictures\Roll-425-04OCT06-BoysSoccerChampionship​\2005-100-JPEG-Main\web_flashright.jp​g

Make - Canon
Model - Canon EOS-1D Mark II N
Orientation - Top left
XResolution - 72.00
YResolution - 72.00
ResolutionUnit - Inch
Software - Adobe Photoshop CS2 Windows
DateTime - 2006:11:06 11:58:17
YCbCrPositioning - Co-Sited
ExifOffset - 228
ExposureTime - 1/250 seconds
FNumber - 4
ExposureProgram - Aperture priority
ISOSpeedRatings - 1600
ExifVersion - 0221
DateTimeOriginal - 2006:11:05 06:59:05
DateTimeDigitized - 2006:11:05 06:59:05
ComponentsConfiguratio​n - YCbCr
ShutterSpeedValue - 1/256 seconds
ApertureValue - F 4.00
ExposureBiasValue - 0
MeteringMode - Center weighted average
Flash - Flash fired, compulsory flash mode
FocalLength - 32 mm
UserComment -
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 640
ExifImageHeight - 427
InteroperabilityOffset - 928
FocalPlaneXResolution - 3098.14
FocalPlaneYResolution - 3098.14
FocalPlaneResolutionUn​it - Inch
CustomRendered - Normal process
ExposureMode - Auto
WhiteBalance - Auto
SceneCaptureType - Standard

EXIF from second image (blown)

File: - U:\Pictures\Roll-425-04OCT06-BoysSoccerChampionship​\2005-100-JPEG-Main\web_flashwrong.jp​g

Make - Canon
Model - Canon EOS-1D Mark II N
Orientation - Top left
XResolution - 72.00
YResolution - 72.00
ResolutionUnit - Inch
Software - Adobe Photoshop CS2 Windows
DateTime - 2006:11:06 11:59:25
YCbCrPositioning - Co-Sited
ExifOffset - 228
ExposureTime - 1/250 seconds
FNumber - 4
ExposureProgram - Aperture priority
ISOSpeedRatings - 1600
ExifVersion - 0221
DateTimeOriginal - 2006:11:05 06:59:58
DateTimeDigitized - 2006:11:05 06:59:58
ComponentsConfiguratio​n - YCbCr
ShutterSpeedValue - 1/256 seconds
ApertureValue - F 4.00
ExposureBiasValue - 0
MeteringMode - Center weighted average
Flash - Flash fired, compulsory flash mode
FocalLength - 28 mm
UserComment -
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 640
ExifImageHeight - 427
InteroperabilityOffset - 928
FocalPlaneXResolution - 3098.14
FocalPlaneYResolution - 3098.14
FocalPlaneResolutionUn​it - Inch
CustomRendered - Normal process
ExposureMode - Auto
WhiteBalance - Auto
SceneCaptureType - Standard

Hermeto wrote in post #2224897
I can see EXIF for both of them and they are the same..

For the rest I admit I might be wrong, but it looks like the first one was shot with the flash not completely recharged, while the second received the full blast on the top of ISO 1600.

It definitely wasn't a recycle issue. Like I said, I took several shots of both teams and they repeated. The batteries were well charged and I just tested the setup here a second ago... and it all works fine here in my office... same equipment, same settings, untouched.

Something about the setting in that second shot caused the flash to be fooled, and I can't figure out what it is.

convergent wrote in post #2224946
It definitely wasn't a recycle issue. Like I said, I took several shots of both teams and they repeated. The batteries were well charged and I just tested the setup here a second ago... and it all works fine here in my office... same equipment, same settings, untouched.

Something about the setting in that second shot caused the flash to be fooled, and I can't figure out what it is.

Perhaps the difference in metering came from the distance in front of the players. In your first image they were closer and reflected the pre-flash better. In the second image the grass won't reflect the light from the pre-flash like the skin/uniforms of the players, possibly fooling the ETTL metering. This is all just a guess.

Hmm, that's interesting..
Metering mode is the same, everything else looks the same..

Prime example of where chimping isn't bad.

Second, if the FEC was cranked you'd know.

I have to agree though, I used to shoot a lot of low light with AV mode. I've since "rediscovered" the virtues of shooting M with ETTL painting in the foreground nicely. Shutter drag is a drag when you don't want it.

What focus point did you use? Perhaps the camera was in fact looking at the rear team?

Hermeto wrote in post #2224983
Hmm, that's interesting..
Metering mode is the same, everything else looks the same..

ETTL uses a preflash to determine its exposure. The metering mode of the camera does not come in to play here, that is for ambient exposure. ETTL can be fooled in certain circumstances. One of these is an image which has a dominating area of bright objects, like white walls. If you have your subject in front of a white wall for example, the preflash will fire and ETTL determines its exposure from the reflective light of the preflash. The white walls will reflect more light than the subject and the metering is now fooled. The shot will be exposed properly for the walls but your subject will be underexposed.

Double Negative wrote in post #2225019
What focus point did you use? Perhaps the camera was in fact looking at the rear team?

From what I have read, E-TTL II does not give any additional weight to the active focus point, like the original E-TTL did.

Double Negative wrote in post #2225019
What focus point did you use? Perhaps the camera was in fact looking at the rear team?

Why would this matter?

I'd like to see the Custom and Personal functions exif data...

Seems like the flash behaved predictably, and exactly correct.

In the first photo, about the top 1/4 of frame is bright, the viewpoint of the shooter is upright at the uniforms in the focus sensor area, which are WHITE, so the the E-TTLII pre-flash meters this (as both % of frame and white clothing), and it REDUCES the power for fill.

In the second photo, the shooters viewpoint angle is downward, and the E-TTLII preflash metering picks up mostly DARK grass and dark maroon uniforms, and tells the flash to bang out the power.

I think the first photo is about a stop+ flash underexposed and the second photo at least 1+ stops flash overexposed.

Exactly the way the metering behaves. Well, behaves as well as any arcane frustrating black art behaves.

I would have done what you did, except I always use M, never Av for fill flash. On the first one, your eye sees the white uniforms, and dials in +2/3 FEC, on the second one, your eye sees dark grass and maroon, and quickly dials in -1 1/3 FEC.
Has to become second nature, and we all screw up. At least I screw up. That's my opinion. Jack