Underexposure, Does it appears in the MK2 or 1D ?

[De Paula]

I'm having a lot of problems with my 10D and 550ex. My photos are very dark and searching on internet I found a lot of people with the same problem.
I take about 800 pictures in each wedding and I can't correct all at photoshop. :wink:
My question is:
Does this problem occurs in the Mark Two or the 1D, or that problem is only known at the Rebel/300D or 10D ?
I read this is a problem with the E-TTL metering system - Maybe it happens on other DSLR including Nikon and Canon.

[robertwgross]

Are you shooting RAW files?

---Bob Gross---

[RichardtheSane]

There is no significan problem with the ETTL metering system but you do have to understand its weaknesses.

Are there any particular type of shot that are coming out underexposed, like the ones with the bride in them?

[De Paula]

I'm shooting in JPEG Large quality.
The light is very inconsistent, sometimes in the same place the photo is okay and another time in the same place with the same aperture and same shutter speed (1/60 5.6) the photo is very dark.
I guess it is a problem with the E-TTL system, sometimes it calculate the light in a clear surface and another time it calculate the light in a dark surface.
I already tried the Flash Exposure Compensation, but in a photo that would be OK w/o the FEC, with FEC the photo was overexposed.
I really need some help.
Thanks,

[Andy_T]

I'm shooting in JPEG Large quality.


Well, don't do that. Use RAW instead.

It's not as if you would have to meet a magazine deadline just half an hour after the final inning.

I'd not be really happy if you photographed my wedding and then explained to me 'Y'know, exposition is sometimes quite off and, sorry, but I shot it in Large JPEG' ... at least not if you do charge money for it.

Best regards,
Andy

[De Paula]

Searchin in the internet I found a lot of people with the same problem...
About RAW - what's different then JPEG ?
Does underexposure happen too ?
Thanks

[Tom W]

RAW does give you some ability to adjust exposure after the fact, but it isn't perfect. With underexposed flash pictures, it can sometimes leave a reddish color cast as you pull the exposure level up. I've noticed this effect both in RAW and in JPEG shots, though RAW generally seems to give better results.

Many folks set their flash exposure compensation at +1/3 to +2/3 stops as a normal setting to help offset the apparent tendency to underexpose. This is helpful only if the underexposure is consistent - if it only happens in some pictures, then there are other causes.

[RichardtheSane]

With RAW you have the capability to correct the exposure to an extent in the conversion software, and you can in some cases get more detail out of the file.

ETTL can gets easily confused by white, more so than the camera metering so when the bride wears white, and say the groom is in black then you have got a confused flashgun.

I have never had my 550ex give me a bad exposure unless I make a mistake. In difficult to meter situations then I tend to use FEL :)

[De Paula]

"...then there are other causes."

Could you tell me about those another causes ?

[De Paula]

...I'm thinking to come back to my EOS 5 with 540ez - The photos with these are perfect ! :roll:

[De Paula]

by the way, RAW mode will not resolve my problem, will it ?

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http://www.robgalbraith.com/ubbthreads/showflat.php?Cat=&Number=227234&page=&view=&sb=5&o =&fpart=all&vc=1
"My frustration with the combination of the 550EX flash and TWO DIFFERENT 10D digital SLRs continues to grow. I've spent hours combing through the web, trying to discover the "magic bullet" that would, once and for all, eliminate the single-most frequent problem I have with this demonic photographic combination: underexposure"
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http://photography-on-the.net/forum/showthread.php?t=30998&postdays=0&postorder=asc&hi ghlight=wedding&start=0
"I've noted that images are underexposed when I use my Canon 420EX flash with my 10D. I can set the flash exposure to overexpose slightly to fix this, but I'm wondering why this is?"
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http://photography-on-the.net/forum/showthread.php?t=26852&highlight=underexposure
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http://photography-on-the.net/forum/showthread.php?t=26961&highlight=underexposure
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http://photography-on-the.net/forum/showthread.php?t=27307&highlight=10d+underexposure
"It seems I'm not alone with underexposure problems when using flash..."
"I've checked out the excellent sites explaining ETTL systems, and I understand the system now, but every flash photo I've taken so far in EVERY mode is consistently underexposed."

[Tom W]

The E-TTL system biases exposure towards the active focus point. I think that its been pointed out already that if your active focus point is in front of a dark object, you will tend to overexpose the picture, whereas if it is in front of a light object (wedding dress or a window comes to mind), you'll likely underexpose. Also note that the system reads light at the time of exposure, not when you might pre-focus. So, if you use the shutter button halfway to prefocus and then compose your picture, the flash will calculate the lighting needs based on where the lit active focus point is when you release the shutter. If it is a bright window behind and between the bride and groom, then you will again underexpose.

Another thing I've seen happen is taking shots too rapidly in succession or with slightly weak batteries. As the batteries get used, the time required to recharge the flash gets longer and longer. The result is that the next picture may not have a full-strength flash available.

Also, E-TTL on the 10D provides an automatic fill-flash reduction. This is usually OK, but can be a problem with a strong backlit subject. You can turn this feature off with one of the custom functions.

Have you read the excellent article on the E-TTL system here:

http://photonotes.org/articles/eos-flash/

It has all kinds of information that you may find useful.

[De Paula]

is there a way to put the 550ex work like a 540ez using the Flash Exposure Lock ?

[Andy_T]

by the way, RAW mode will not resolve my problem, will it ?



It can help if your picture is underexposed, but it does not do miracles. Noise will go up. However, the photo might still be usable as opposed to not.

If you overexpose, RAW also can not help much.

Best regards,
Andy

[De Paula]

by the way, RAW mode will not resolve my problem, will it ?



It can help if your picture is underexposed, but it does not do miracles. Noise will go up. However, the photo might still be usable as opposed to not.

If you overexpose, RAW also can not help much.

Best regards,
Andy

My problem is only underexposure.
So, there is no difference between RAW and JPEG because I can adjust curves and levels inside Photoshop.

But my problem is: I take about 500 photos in a wedding, I don't have time to correct one by one.
I only want a consistent light quality in my pictures.

Regards,

[Andy_T]

There's that BreezeBrowser example (from the help file):

You can correct this

http://www.breezesys.com/BreezeBrowser/help/standrews_uncorrected.jpg

to look like this

http://www.breezesys.com/BreezeBrowser/help/standrews_corrected.jpg

Now shoot me if I'm wrong, but I think I rmember that RAW conserves 12 bit of colour information, vs. only 8 bit in JPEG (and that extra 4 bit come in handy when lighting up an underexposed photograph).

Somebody who knows this - please correct me if I'm wrong.

Best regards,
Andy

[De Paula]

Yes, you are right.
But I don't want to know how can I correct an underexposured image.
I just wanna know how can I take all my photos with a correct exposure like in the 35mm film.

Best Regards,

[Andy_T]

But my problem is: I take about 500 photos in a wedding, I don't have time to correct one by one.
I only want a consistent light quality in my pictures.

Regards,

You don't HAVE to correct each photo one by one, once you have a workflow established (e.g. using C1 DSLR and PS). But it offers you the possiblity to correct those that are not correctly exposed.

BTW, the photos on your website surely do look impressive :D

Best regards,
Andy

[robertwgross]

Andy, it certainly sounds like the original poster has a mind made up against RAW, so there isn't any further point to it.

---Bob Gross---

[De Paula]

But my problem is: I take about 500 photos in a wedding, I don't have time to correct one by one.
I only want a consistent light quality in my pictures.

Regards,

You don't HAVE to correct each photo one by one, once you have a workflow established (e.g. using C1 DSLR and PS). But it offers you the possiblity to correct those that are not correctly exposed.

BTW, the photos on your website surely do look impressive :D

Best regards,
Andy

OK, I'll test some combinations.
Thanks for the comment. :wink:

[De Paula]

is there a way to put the 550ex working like a 540ez ?

[Tom W]

I'm not sure how the 540EZ functions, but I believe that the 550EX does have a manual mode. Somebody with experience with the 550 is going to have to help you with this one. I have the 380EX.

[De Paula]

And, Does the underexposure problem happening with Canon 10d and D.Rebel are caused due to E-TTL technology ?
So, Canon Mark II doesn't has this problem because it uses E-TTL II, does it ?

Thanks,

[Pekka]

is there a way to put the 550ex working like a 540ez ?

If you mean "old" TTL mode the yes, 550 can be set to TTL mode. I don't have the manual here at hand, though.

[Tom W]

And, Does the underexposure problem happening with Canon 10d and D.Rebel are caused due to E-TTL technology ?
So, Canon Mark II doesn't has this problem because it uses E-TTL II, does it ?

Thanks,

Hi, finally getting back to you. My understanding is that E-TTL II uses a better, more sophisticated approach to analyzing light in the flash zone, and is supposed to be much better at getting accurate flash.

I can't say for certain as I don't have a 1D Mk II. I will say that while I haven't shared your situation with underexposure, I have had some inconsistent results with flash on my 10D. Many were solved by keeping very fresh batteries in my 380EX flash. Others were resolved by altering custom function #14 to disable the automatic fill-flash reduction. My third issue has been harder to resolve and that is the inconsistency caused by E-TTL's use of the active focus point for exposure bias. While this works well most of the time, there is no easy way to disable or alter that function.

[De Paula]

I have had some inconsistent results with flash on my 10D
This is my problem.

Many were solved by keeping very fresh batteries in my 380EX flash.
I think it's not the cause, because if I put a new batteries into my 550ex the photos were with the same problem.

Others were resolved by altering custom function #14 to disable the automatic fill-flash reduction.
I already tried it. :(

My third issue has been harder to resolve and that is the inconsistency caused by E-TTL's use of the active focus point for exposure bias.

Here is the key of the problem ! The question is: Is it a characteristic of E-TTL (1) ?

Thanks - :D

[Tom W]

My third issue has been harder to resolve and that is the inconsistency caused by E-TTL's use of the active focus point for exposure bias.

Here is the key of the problem ! The question is: Is it a characteristic of E-TTL (1) ?

Thanks - :D

OK, probably the most important point to remember is that the bright white dress and the dark blue/black suit will, if they are the main focus point, cause you some trouble on your exposure. This is characteristic of E-TTL-1, though I hadn't heard any complaints with that system when used on film (perhaps its related to digital's smaller field of view or print film's very wide lattitude, I really don't know). Anyway, I've not had any exposure problems with E-TTL-1 on my Elan II film camera, though I don't use it much these days.

I'm thinking that if you find a way to set things up so that your active focus point doesn't hover over the dress, a dark suit, or any other very bright/dark large object, then you'll be OK. Naturally, that's easier to say than to do. People at festive occasions aren't going to put themselves in studio poses for you.

I haven't tried this trick yet (and it might not work anyway), but perhaps you may need to carry some kind of 18% gray backdrop or card or something like that so that you can focus and then recompose such that your active focus point is over that gray material. Then shoot the shot.

BTW, did you read that long essay that I linked to earlier? That has a ton of information on how E-TTL -1 works.

[De Paula]

Maybe this: (http://www.imaging-resource.com/NEWS/1075434066.html) is the answer, right ?

"Canon has totally overhauled its E-TTL flash metering system for the EOS-1D Mark II, and E-TTL II should fix perhaps the biggest bugbear with the old system. The original E-TTL worked on the assumption that the autofocus point would cover the subject - a logical assumption that was usually the case, but was thrown off when you prefocused and then reframed the image. E-TTL II works to correct this problem as follows: (description courtesy of Canon)

"In the new algorithm, ambient light is measured when the shutter button is pressed. Next, a pre-flash is fired and the metering sensor takes readings at the central 17 metering zones. The ambient and pre-flash readings are compared. The metering areas having a small difference are selected as the flash exposure metering areas. (Areas with very big differences between ambient and pre-flash readings are excluded or down weighted because they are assumed to contain a highly reflective object or that the subject is not in that part of the frame. The algorithm avoids chronic underexposure problems in such situations.) These readings are weighted, averaged and compared with the ambient light reading, and the main flash output is then set and stored in memory. E-TTL II weights and averages the flash metering for the subject and all other objects at the same distance as the subject. Even if the subject’s position, reflectance or size changes, the flash output will not change radically. The flash exposure will be highly accurate and stable. Most EF lenses provide distance information, and this data is also considered in determining if there is a highly reflective object, once again lessening the chance of underexposure"

[Tom W]

Maybe this: (http://www.imaging-resource.com/NEWS/1075434066.html) is the answer, right ?

"Canon has totally overhauled its E-TTL flash metering system for the EOS-1D Mark II, and E-TTL II should fix perhaps the biggest bugbear with the old system. The original E-TTL worked on the assumption that the autofocus point would cover the subject - a logical assumption that was usually the case, but was thrown off when you prefocused and then reframed the image. E-TTL II works to correct this problem as follows: (description courtesy of Canon)

"In the new algorithm, ambient light is measured when the shutter button is pressed. Next, a pre-flash is fired and the metering sensor takes readings at the central 17 metering zones. The ambient and pre-flash readings are compared. The metering areas having a small difference are selected as the flash exposure metering areas. (Areas with very big differences between ambient and pre-flash readings are excluded or down weighted because they are assumed to contain a highly reflective object or that the subject is not in that part of the frame. The algorithm avoids chronic underexposure problems in such situations.) These readings are weighted, averaged and compared with the ambient light reading, and the main flash output is then set and stored in memory. E-TTL II weights and averages the flash metering for the subject and all other objects at the same distance as the subject. Even if the subject’s position, reflectance or size changes, the flash output will not change radically. The flash exposure will be highly accurate and stable. Most EF lenses provide distance information, and this data is also considered in determining if there is a highly reflective object, once again lessening the chance of underexposure"

Interesting quote. Yes, it sounds like Canon was listening a bit. Unfortuantely for me, my old habits are to prefocus, frame, and then shoot. I try to consciously avoid that trap when shooting flash, but its something I learned long ago and is a hard habit to break. And its a good habit when shooting anything other than flash.

For you as a professional, I'd say that unless someone else here comes up with some better information (and I know that there are people shooting weddings successfully with the 10D), the 1D Mk II might be a good choice. For myself as an amateur, its not something I'll be buying so soon. But a few years down the road, who knows....

[De Paula]

Mark II is very expensive here in Brazil, only to you have an idea:
Here the price of 10D is (in "R$")
10D Body: R$ 5900,00 (It's the dollar multiplied by 3 including all the imports fee)

Mark II Body: R$ 24.500,00 (It's the dollar multiplied by 3 including all the imports fee)

You know... it's impossible to buy a MARK II here, because you can buy FOUR (04) 10D :(

[De Paula]

I was thinking:
"Maybe the problem can be solved if I change Canon for Nikon..."

If I buy a D100 my problem will be solved ?
How is the flash metering system on a Nikon D100 ? Is it better than Canon E-TTL ?
Is it like E-TTL 2 ?

Help...

[Tom W]

In an effort to help you, me, and others, I did a little experimenting with ETTL on my 10D and 380EX flash. Here's a pair of shots that illustrate how the camera follows the focus point and exposes based on where it is located at the time of exposure. These are cropped so that you can't see the dirty kitchen in the background (that I should be cleaning instead of playing with my camera). :)

Anyway, both were shot with +1/3 stop flash exposure compensation as this seems to give me good results.

In the first shot, I focused on the dark coat and then took the shot while the focus point was over the coat. The coat exposed well, as did the entire scene.

http://images.fotopic.net/?id=4262410

In this next shot, I again focused on the coat, but I then held the shutter button halfway down to lock focus, and recomposed such that the active focus point was right over the light-colored wall. The result was a somewhat underexposed shot, perhaps about 1 stop under (my guess).

http://images.fotopic.net/?id=4262408

The second shot is still salvageable, but if I had a purely white wall (like a typical wedding dress), I might have had even weaker exposure that may or may not be saved even in RAW.

It would be easy for me to say that you should keep that active focus point away from the extremely white subjects, but this would be very difficult at a wedding. The other alternative is to use flash exposure lock, but I'm not fond of the pre-flash while setting exposure.

I know that E-TTL works very well in most circumstances, but I really wish that Canon would make available a means to lower the amount of focus-point bias that the camera uses. That would resolve the issue and allow us to use flash more effectively in those situations where extremely light or dark subjects can easily throw off the flash.

PS - Click on the images to get the proper 600X400 size.