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Old Dec 8, 2004, 9:13 PM   #11
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I also own the Digital Rebel and have noticed the same under exposure problem. I am/was seriously thinking of upgrading to the 20D hoping this problem would be fixed. After reading the forums, I will seriously reconsider and probably just stick with the Rebel. I have found that setting the FEC to +2/3 via software I downloaded from the internet has helped the problem a bit although at times, I now get some exposures which have overexposed areas or skintones. Very frustrating. On the 20D, I thought this problem was supposed to be fixed with the new E-TTL II logic however it appears not to be the case. So what did E-TTL II realy improve?? I have a lot of support equipment invested in the Canon product line (2 dedicated flashes EX420 and EX550 as well as 4 lenses). That's why I wanted to stay with Canon and go with the 20D. Does anyone know if the Nikon D70 has this problem??? At this point, I may be tempted to cut my losses and switch over to the NikonD70. I have hadowned 2 NikonCoolPix cameras in the past and have never experienced the underexposure problem....
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Old Dec 17, 2004, 4:32 PM   #12
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I experienced the same problem. None of the automatic modes would take a properly exposed pic indoors. Usually had to compensate with +1 or so on the flash and overexpose to boot. Also had to manually adjust the white balance with a white card or wall before colors came out close to right in artificial light.
After messing with it for a week I returned it and bought a competitor's D-SLR which I am very happy with.
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Old Dec 19, 2004, 1:29 PM   #13
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I am experiencing the same problem with my new 20D. Other than this, significant, problem, I have beenvery happy with the camera. Thanks to all for the suggestions; I will give them a try. I agree with Don that this does seem like too big a problem to be present in a $1500 camera. Has anyone spoken to Canon? If so, did they have anything helpful to say?

Jennifer
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Old Jan 13, 2005, 12:57 PM   #14
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Hi,

I am new to the forum, but someone asked if Canon had been contacted about the dark flash pictures. I have talked to Canon twice and they just kept telling me the exposure is based on the focusing point. I emailed 4 jpegs to their customer service and the reply was that they could not analyze the dark pictures because all of the data was not there as a jpeg and I was getting a replacement camera anyway. My first 20d underexposed by 2 stops. My replacement underexposes by only 1 stop...so I guess that's a little better.

I then sent 7 raw images to customer service. They looked at the first one, which was a person feeding a cat out of a white bowl. They said I chose the wrong exposure mode, center-weighted, instead of evaluative. Had they looked at the other images I sent, they would have seen that I also tried ALL of the exposure modes.

I'm not sure if I will keep the camera or not. I generally do not use the on board flash alot and the camera seems to work fine for non flash photography. I am less than thrilled with Canon's service at this point as well as the flash. I think 1/2 stop under may be acceptable, but 1-2 stops is not.

I will be emailing Canon support yet again.
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Old Jan 13, 2005, 8:19 PM   #15
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The following link helped me a lot (along with help from the members of this forum):

http://www.photography-on-the.net/fo...ad.php?t=46599

In particular, read the threads for the link"How ETTLII Works"

Chuck Westfall from Canon states "E-TTL II is never linked to the active focusing point. In fact, that is one of the main differences between E-TTL II and the original version of E-TTL."

Also,

Creative modes (except for P-Auto) always have the flash as "fill flash" ... so, if flash is required to illuminate the subject, and there isn't enough ambient light, you may need to use some flash exposure compensation. P-Auto can be tricky since it will adjust to/from fill flash mode automatically based on the ambient light available.

The basic modes only automatically increase ISO to 400 ... so if there isn't enough light available your pictures may be underexposed.

I believe that FE lock isn't linked to the "active" focus point, but to the "partial metering" area in the middle of the viewfinder.

AE lock is linked to the active focusing point.

When you press the shutter down halfway, "ambient" light is metered. There is an almost un-noticeable preflash that goes off just before taking the picture ... this preflash information is compared with the ambient light readings, and a correct exposure is determined after a bunch of calculations are made.

Setting the focus mode on the camera has no bearing on ETTL-II flash metering.



I'm certainly no expert ... just a noob ... and I'm trying to learm myself. So if I'm incorrect on any of the above I would certainly like to hear



Bob
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Old Jan 14, 2005, 5:32 AM   #16
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BobA wrote:
Quote:
I believe that FE lock isn't linked to the "active" focus point, but to the "partial metering" area in the middle of the viewfinder.

AE lock is linked to the active focusing point.
I noticed this too if you mean by AE lock is performed by holding down the camera shutter 1/2 way...

... and FE lock with the * button is "partial metering", I saw this documented only in the 300D/DRebel manual but none on the other cameras, but I concur with your results here



Quote:
"E-TTL II is never linked to the active focusing point. In fact, that is one of the main differences between E-TTL II and the original version of E-TTL."
This is not a very accurate info, they are both link to the active AF point: Whereas the E-TTL looks at the luminosity of the object(s) around the active AF point, the E-TTL II get the distance info from the lens to the object picked by the active AF area and determines its exposure ignoring it's brightness value - This is very similar to the old day when one determines an exposure (aperture) value by dividing the Guide Number to the subject distance... (or change the power setting of the flash by keeping the aperture fixed).
Of course E-TTL II can't get this info on older lenses, like my 85mm f/1.2 or if the AF/M switch on the lens is switched to manual where it'll revert to E-TTL!
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Old Jan 14, 2005, 8:19 AM   #17
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Hi NHL,

In the same description of how ETTL-II works from Chuck Westfall he states:

"As I've mentioned in previous posts, the setting of the focus mode switch on the lens has no bearing on E-TTL II flash metering"

Is his comment wrong, or just a "half-truth"?:?



Bob
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Old Jan 14, 2005, 9:43 AM   #18
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1/2 truth - IMO how would the camera 'knows' where you focus manually with the focusing ring?

1. This could be different from the active AF point (especially with macro-extender)
2. Some older Canon lenses does not provide the distance info so how would E-TTL 2 compute?
"1. E-TTL II will factor in distance information when it is available during direct flash operation, regardless of the C.Fn 14 or C.Fn 4 setting. Standard E-TTL does not use distance info."

3. Bounce flash can't use distance either!
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Old Jan 19, 2005, 11:37 AM   #19
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Iam having similar issues with the 20D. Tried the 20D withCanon 17-40 F4L, 70-200, F4L, Tamron 28-200,and 580EX.
  • Tried in full auto and like someone pointed out, the ISO was set automatically at 400. Pictures still came out slightly underexposed (corrected at +1). [/*]
  • Attempted same picture using "P" and the result was the same. However, the colors were normal (good contrast) on the well lit surfaces (roof tops, etc.), but pictures were still dark (visibly and on histogram). Parameters and CFn. were all set to default for all shots.[/*]
  • Attempted indoor shots with "P" and auto and 580EX flash on auto and the result was the same. All pictures had to be corrected by +1.[/*]
  • Shots were taken with all three different metering modes. Results on exposure were the same (very slight difference).
[/*]
Called up Canon Tech support and they started out with the usual on having me try shots with and without filter, switching lenses,etc. and the results have not changed. I guess I also read somewhere else on this forum or other forums that Canon D-SLR's sensors are set to shoot at 2/3 to 1/2 step lower exposure. Adding what Canon told me and what they offered (send new camera in for service), I am still waiting to see if this is an issue with the 20D product line or if it was just my camera - looks like it's the 20D product line.
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Old Jan 19, 2005, 9:03 PM   #20
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I doubt that anything is wrong with your 20D ...

It mightthat flash exposure problems are mainly due to Canon having extremely poor documentation as to how E-TTL II works. The camera likely works as designed ... just not as "expected" by most users.

I recently receiveda response fromCanon saying that ALL modes (except sports) use fill-flash, including Manual. Some of the other info they provided was "strange", but this small tidbit helps explain things a lot. For example:

- If the flash is used as fill, then it would be difficult to get consistent exposures unless the background could be correctly exposed, and FEC would typically need to be used. Gee ... this sounds familiar.

- Non E-TTL flashes would give more predictable (to a user knowledgeable about using flash) results than an EX series flash or the on-board flash.

I've asked a few more questions from their tech support to confirm the above, so hopefully they will get back to me soon. I especially want to know if there is auto fill flash reduction inALL modes below a certain EV. I also have a feeling that Canon uses a calculation of EV that looks at ISO and luminance, not simply EV=log2(Av^2/Tv).

At least knowing that I will always have to use FEC with my 420EX has really improved my pictures.I can now consistently get photos with the kind of exposure that I like with very little digital exposure compensation being required during post production.

Also if you use flash exposure lock with the partial metering circle filled by an 18% grey card the results are always perfect. FE lock is very tricky since it meters using the 9.5% center circle of the viewfinder ... so if it is pointed at something white it will underexpose ... black it will overexpose. If it isn't an average of 18% grey in the partial metering circle, the exposures using FE lock will definitely be off.

I've only had my 20D for a few weeks, but have really enjoyed learning about it. It's a great camera, but it isn't a point and shoot ... so you really have to take some time to get used to how it works. If only Canon would read the forums and understand that they have to put in much greater effort with regards to educating users. For example, when I bought my first SLR (an Olympus OM-1 MD), Olympus sent me a newsletter with tips on a regular basis forthe first year I owned the camera. I loved that camera ... if it had auto-focus I never would have traded it in for my Canon Elan II. O well.



Regards,

Bob
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