10D and 550EX = dark pictures

[Perfect_10]

OK .. I'm having some problems here.
Portrait pictures .. subject is 6 feet away.
I have my 10D with 17-40 lens sat on a tripod. 550EX is set to ETTL, and the camera is in portrait mode .. and is showing a 60th at f/4. The distance scale on the flash will go to 13m on the distance scale.

So mt question is .. why does the flash fail to illuminate the subject properly if I move back to 8 - 10 feet .. the picture is dark, and the histogram shows a it is under exposed. Surely these flashes are more powerful than this.
Actually, I haven't used this flash much .. but every time I do I must say I'm disappointed with the exposure .. pictures always seem too dark.
What am I missing here.

[FlipsidE]

Curious...do you have the flash on a bracket with a movable arm? If not, it may only really be lighting from one side which could cause an issue. This is just a guess though.

FlipsidE

[scottbergerphoto]

Take a look Here (http://photography-on-the.net/forum/showthread.php?t=46599)
Many factors can result in flash underexposure. To name a few:
1. Automatic Fill Flash Reduction.
2. A highly reflective subject or background.
3. Failure of the flash to fully recycle.
4. Trying to bounce off a high ceiling.
5. Trying to cover too far a distance. (D=GN/ f stop)
6. A malfunctioning flash / Off The Shoe Cord 2
7. Accidental setting of (-) FEC
Scott

[Perfect_10]

no .. it's sitting on top of the camera. The whole subject seems dark .. like it's under exposed.

[slin100]

Some other possibilities:
Classic ETTL underexposure
It's been my experience that flash exposures always come out 2/3 to 1 stop underexposed. Dialing in +2/3 FEC usually does the trick for me.
Focus-point based flash metering
On a 10D, ETTL flash exposures are heavily biased to the active focus point. If the active focus point is on something bright, flash underexposure will occur. Enabling C.Fn 4 to remap focus to the * button decouples flash metering from focus points and forces average metering. You can also try FEL, which meters off of the partial metering circle.

These two points are probably documented in one of the links in the EOS Flash Sticky.

[scottbergerphoto]

Some other possibilities:
Focus-point based flash metering
On a 10D, ETTL flash exposures are heavily biased to the active focus point. If the active focus point is on something bright, flash underexposure will occur. Enabling C.Fn 4 to remap focus to the * button decouples flash metering from focus points and forces average metering. You can also try FEL, which meters off of the partial metering circle.


Steve,
I believe that in order to to get flash metering to average in ETTL, even using Cfn. 4, you need to release the * button after focusing. If not, you will still have active AF points to bias the flash.
That's what it says Here (http://visual-vacations.com/Photography/1ds_and_ettl_flash.htm)
Scott

[Perfect_10]

Some other possibilities:
Classic ETTL underexposure
It's been my experience that flash exposures always come out 2/3 to 1 stop underexposed. Dialing in +2/3 FEC usually does the trick for me.
Focus-point based flash metering
On a 10D, ETTL flash exposures are heavily biased to the active focus point. If the active focus point is on something bright, flash underexposure will occur. Enabling C.Fn 4 to remap focus to the * button decouples flash metering from focus points and forces average metering. You can also try FEL, which meters off of the partial metering circle.

These two points are probably documented in one of the links in the EOS Flash Sticky.

Thanks .. I will try these tonight. I have never been happy with the flash metering of this camera/flash combo .. but until now it's not really been that big an issue, but as the wife was running off some portrait style pics it became a big problem.

[PacAce]

It sure would be nice to be able to see the picture you are talking about. As Scott pointed out, there can be a lot of reasons why you flash picture came out underexposed and without seeing the actual picture, it's hard to make a diagnosis and a specific recommendation.

And as for the FEC compensation requirements, my experience has been that I may need +2/3 exposure, -2/3 exposure or 0 exposure compensation depending on the subject being photographed as well as the characteristics of the background (or the lack or, for that matter).

[scottbergerphoto]

See my note to Steve above and the link included.
Scott

[slin100]

Steve,
I believe that in order to to get flash metering to average in ETTL, even using Cfn. 4, you need to release the * button after focusing. If not, you will still have active AF points to bias the flash.
That's what it says Here (http://visual-vacations.com/Photography/1ds_and_ettl_flash.htm)
Scott
That's correct.

[Perfect_10]

It sure would be nice to be able to see the picture you are talking about. As Scott pointed out, there can be a lot of reasons why you flash picture came out underexposed and without seeing the actual picture, it's hard to make a diagnosis and a specific recommendation.

And as for the FEC compensation requirements, my experience has been that I may need +2/3 exposure, -2/3 exposure or 0 exposure compensation depending on the subject being photographed as well as the characteristics of the background (or the lack or, for that matter).

I don't have pictures with me .. but they are all underexposed. I experimented last night by setting the camera to manual (60th f/4), single focus point enabled, and FEC wound up to +1. Now the pictures seem OK (histogram shows correct exposure). I think the lack of background is playing a big part in this.

[scottbergerphoto]

It sure would be nice to be able to see the picture you are talking about. As Scott pointed out, there can be a lot of reasons why you flash picture came out underexposed and without seeing the actual picture, it's hard to make a diagnosis and a specific recommendation.

And as for the FEC compensation requirements, my experience has been that I may need +2/3 exposure, -2/3 exposure or 0 exposure compensation depending on the subject being photographed as well as the characteristics of the background (or the lack or, for that matter).

I don't have pictures with me .. but they are all underexposed. I experimented last night by setting the camera to manual (60th f/4), single focus point enabled, and FEC wound up to +1. Now the pictures seem OK (histogram shows correct exposure). I think the lack of background is playing a big part in this.
The lack of a background should actually increase flash exposure. The flash output is controlled by the amount of pre flash reflected back to the camera. A highly reflective surface like a white background or white dress kicks alot of the light back resulting in decreased flash. (ETTLII is supposed to reduce this). In the abscence of a background(or with a black tuxedo), less pre flash is reflected back resulting in more flash output(ETTLII is supposed to reduce this also).
Regards,
Scott

[slin100]

I don't have pictures with me .. but they are all underexposed. I experimented last night by setting the camera to manual (60th f/4), single focus point enabled, and FEC wound up to +1. Now the pictures seem OK (histogram shows correct exposure). I think the lack of background is playing a big part in this.
Did you remap focus to the * button? If not, then exposure is still being based on the active focus point on your 10D. If the focus point was on the subject, then the background should have had little or no influence at all on flash metering.

Since you seem to have gotten a reasonable histogram with +1 FEC, I think you are experiencing the classic ETTL underexposure syndrome.

[Perfect_10]

It sure would be nice to be able to see the picture you are talking about. As Scott pointed out, there can be a lot of reasons why you flash picture came out underexposed and without seeing the actual picture, it's hard to make a diagnosis and a specific recommendation.

And as for the FEC compensation requirements, my experience has been that I may need +2/3 exposure, -2/3 exposure or 0 exposure compensation depending on the subject being photographed as well as the characteristics of the background (or the lack or, for that matter).

I don't have pictures with me .. but they are all underexposed. I experimented last night by setting the camera to manual (60th f/4), single focus point enabled, and FEC wound up to +1. Now the pictures seem OK (histogram shows correct exposure). I think the lack of background is playing a big part in this.
The lack of a background should actually increase flash exposure. The flash output is controlled by the amount of pre flash reflected back to the camera. A highly reflective surface like a white background or white dress kicks alot of the light back resulting in decreased flash. (ETTLII is supposed to reduce this). In the abscence of a background(or with a black tuxedo), less pre flash is reflected back resulting in more flash output(ETTLII is supposed to reduce this also).
Regards,
Scott

My wife has just informed me that by shooting up off a ceiling (2 clicks off horizontal) the exposures are spot on. Seems that shooting directly at the subject is causing the flash to cut off, thereby underexposing the shot. How can that be ??

[Perfect_10]

I don't have pictures with me .. but they are all underexposed. I experimented last night by setting the camera to manual (60th f/4), single focus point enabled, and FEC wound up to +1. Now the pictures seem OK (histogram shows correct exposure). I think the lack of background is playing a big part in this.
Did you remap focus to the * button? If not, then exposure is still being based on the active focus point on your 10D. If the focus point was on the subject, then the background should have had little or no influence at all on flash metering.

Since you seem to have gotten a reasonable histogram with +1 FEC, I think you are experiencing the classic ETTL underexposure syndrome.

yep .. tried the remap * button .. didn't seem to make any difference at home. I'm assuming the camera is underexposing as you state. This is definately a PITA.

[slin100]

What is the subject and how far away is it? If the subject is white, that could explain the underexposure.

[Perfect_10]

What is the subject and how far away is it? If the subject is white, that could explain the underexposure.

Subjects are playschool kids (one by one .. not a group) .. sat about 5 - 6 feet away .. and all various color shirts/tops.

[kafene]

no .. it's sitting on top of the camera. The whole subject seems dark .. like it's under exposed.

My 10D seems fine with that combo, BUT my 20D and 550 have the exact issue you're having.

kafene.