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Old Jun 2, 2004, 3:30 PM   #1
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I have my 300D since last October, and I've made a lot of pictures with it. Generally I am happy with it, but I frequently run into two major exposure problems for which I don't have an explanation or don't know how to solve. I have read the Doug Kerr overview (excellent by the way), the Canon workshops and everything I could find, but that doesn't solve my problem. I have had several Canon camera's, both analog SLR and digital compact, so I'm not a complete photography n00b… But I do have a big digital camera challenge: my major topic is black and white dogs…

Before starting to accuse Canon of supplying me with a malfunctioning camera, I hope some of you have smart ideas?



Examples (incl. EXIF-data) are posted at http://www.xs4all.nl/~dcbjht/300D/. The original pictures (not touched by Photoshop or any other software) are also posted, but they are quite large, please note before you start downloading. And please, only download them if you really need them, since monthly bandwidth usage is limited ;-)



Problem 1 (see picture 1A and 1B)

For me, it's impossible to use some kind of center-weighted metering with black and white dogs. If the center is the white part of the dog (picture 1A), the picture is underexposed; if the center is the black part of the dog (picture 1B), the picture is overexposed. Anyone has an intelligent solution (apart from: ‘avoid any form of center-weighted metering, and thus Manual mode', or: ‘buy another color dog')?



Problem 2 (see pictures 2A/B and 3A/B)

All 4 pictures are using Program AE, the kit lens and evaluative metering. Picture 2A and 2B are 4 seconds apart (constant ambient light, so no sudden shadow or sun change) and shot at the same focal length. Picture 3A and 3B are taken one month later, only 1 second apart, with the same settings. Can anyone explain why both times one of the pictures is extremely over-exposed? Or better: can anyone give me some suggestions how to avoid this? These are just 2 examples of a problem that occurs very frequently, and which I wouldn't expect with evaluative metering.



Thanks,

Miriam






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Old Jun 2, 2004, 7:42 PM   #2
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Your text has an exposure problem that I can't read ... yellow on white is too difficult for my old eyes. Sorry.
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Old Jun 2, 2004, 10:38 PM   #3
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I would suggest getting a book on old school photgraphy and reading it. Judging by your post, I would have to assume that you are not intimately familiar with how an AE meter in a camera works.

The way they determine exposure is to meter an entire scene (or what it is metering off of in terms of center weight) to 18% grey, which is a largely neutral tone. This is usually ok, because you have a large variation of tones in a scene usually. The problem is, when metering off of a mostly dark or light subject, the camera tends to either underexpose (light scene) or overexpose (dark scene). The way to comensate is to use Exposure Compensation (the button on the back that says Av and the +/- symbol) to force the camera to over or underexpose the scene.

I hope that helps as far as the pooches go. I didn't actually go to your website, cause I am on dialup, and I don't have the time (or patience) to wait for large files to download. I was kinda shootingblind with my exposure tip, so I hope it helps!
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Old Jun 3, 2004, 5:53 AM   #4
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That's a radical variation. Does it only happen with black and white dogs as a subject?

Ifithappens with all kinds of subjects I would eithertake a stab at updating the firmware or return it for servicing.

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Old Jun 3, 2004, 6:09 AM   #5
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BizzyBee wrote:
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Before starting to accuse Canon of supplying me with a malfunctioning camera, I hope some of you have smart ideas?

IMO this is no different than shooting brides and grooms with overwhelming White and Black (or subject in snow or sand) which can fool any camera metering if not careful!

Like you said the exposure is pretty much constant with the same daylight relative exposure: use a Kodak grey card to set the exposure (and what's the camera is calibrated for anyway like Gandalf 065 has described)... This way the exposure is independent from the subject reflectance and will immediately tell if your camera is faulty or not...

BTW the flip side of the Kodak grey card is white so you can useit to set the WB as well :idea:
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Old Jun 4, 2004, 7:56 AM   #6
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Come on guys, IMHO these kinds of exposure variations are not to be expected from a camera such as the 300D/Rebel.

If you look at the examples (the webpage shows thumbnails, full size images are available from links below the thumbnails, so even dial-up visitors can take a look!) you must agree that the differences are horrible. The dog has the same position, but only turned its head and the 300D doesn't know how to expose it correctly?:?

My ancient Oly C-2002Z does a better job at picking the correct exposure (it has a mystery iESP metering algoritm, but at least it shows detail in both the black and white areas of my dogs).

I was considering a 300D, but features like this really changed my mind. Exposure problems like this were already spotted at http://www.dcresource.com/reviews/ca...ew/index.shtml, but at the time thought to be an accident.
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Old Jun 4, 2004, 6:30 PM   #7
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One problem with the 300D evaluative metering is that it is very heavily biased to the focus point(s). So if you have one shot that has focused on a black area, and another that has focused on a white area, the exposure will be vastly different between the two.

For me, this is the biggest weakness of the camera. You could always use the 'Manual' program setting, which is at least centre weighted metering, and ignores the focus point. While metering off of the subject is often a good idea, that possibility already exists by means of the exposure lock (*) button, which uses 'partial' metering (uses the centre 9% of the image).

Maybe one of these firmware hacks will eventually allow us to change this behaviour...
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Old Jun 5, 2004, 12:09 AM   #8
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gcogger wrote:
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One problem with the 300D evaluative metering is that it is very heavily biased to the focus point(s). So if you have one shot that has focused on a black area, and another that has focused on a white area, the exposure will be vastly different between the two.

For me, this is the biggest weakness of the camera...
Gcogger is entirely correct here, but you guys should have checked out the manual!
If you press the * (ie AE lock button) on the Rebel the metering is changed to partial and only the center ~10% is metered (page 122 of the manual) in any of the creative zone...
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Old Jun 5, 2004, 4:07 AM   #9
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NHL wrote:
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Gcogger is entirely correct here, but you guys should have checked out the manual!
If you press the * (ie AE lock button) on the Rebel the metering is changed to partial and only the center ~10% is metered (page 122 of the manual) in any of the creative zone...
I think that's exactly what Gcogger wrote in the second part of his post....

But let's get things straight: what you're now describing is a work-around the badly implemented Evaluative mode, correct? IMO "Evaluative" means that it takes some kind of average of either the total picture or of the focus points. Which would be good! What I understand the 300D is doing instead is taking one of the focus points at random (in case of more than one focus point) to base the metering on. I would call this "focus point weighted metering" with is almost the sames as center-weighted or partial, only in this case it takes the focus point, and in case of more than one focus points, takes one at random, to base the metering on. This does not make me happy....


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Old Jun 5, 2004, 4:10 AM   #10
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ohenry wrote:
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Your text has an exposure problem that I can't read ... yellow on white is too difficult for my old eyes. Sorry.

I have tried to change the color of the text, but "white" is not available in the drop-down list. :?My background is black, so I need white text....

I was hoping yellow would give the best result on black as an alternative. I'm sorry, I only hope my photography is better than my understaning of the user interface ofthis forum :O
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