Attention *ALL* owners of Ixus 500

I have reported previously a fault in the metering of this camera. Please
check your camera so that we can assess whether all cameras are affected or
only some. The evaluative and centre-weighted metering are transposed. Could
all owners please check their Ixus 500 and report whether or not it has this
fault.

This is how to check:
Correct exposures would be: spot (more than) centre-weightedevaluative.
However, the faulty Ixus 500 gives spot"evaluative""centre-weighted." If
not sure you can read exposures from
downloaded photos into ZoomBrowser EX. (ie spot [lighter/more
exposure]than "evaluative etc

Or: light coloured oblong surrounded by darker area should be
spotcentre-weightedevaluative [spot setting darkest - evaluative
brightest] but "centre-weighted" is brightest - thus wrongly labelled.
means more than; means less than.

This is important as the automatic mode will give wrongly exposed photos.
Canon will correct the fault if there is enough evidence that it is present
in all cameras. PLEASE CHECK

Thanks,
Peter

"Peter McKenzie (remove 'nospam')" wrote in
message ...
I have reported previously a fault in the metering of this camera. Please
check your camera so that we can assess whether all cameras are affected
or
only some. The evaluative and centre-weighted metering are transposed.
Could
all owners please check their Ixus 500 and report whether or not it has
this
fault.

This is how to check:
Correct exposures would be: spot (more than) centre-weightedevaluative.
However, the faulty Ixus 500 gives spot"evaluative""centre-weighted." If
not sure you can read exposures from
downloaded photos into ZoomBrowser EX. (ie spot [lighter/more
exposure]than "evaluative etc

Or: light coloured oblong surrounded by darker area should be
spotcentre-weightedevaluative [spot setting darkest - evaluative
brightest] but "centre-weighted" is brightest - thus wrongly labelled.
means more than; means less than.

This is important as the automatic mode will give wrongly exposed photos.
Canon will correct the fault if there is enough evidence that it is
present
in all cameras. PLEASE CHECK

Thanks,
Peter

Can't canon check on the cameras it has?

-Jack

"Peter McKenzie \(remove 'nospam'\)" wrote in
:

I have reported previously a fault in the metering of this camera.
Please check your camera so that we can assess whether all cameras are
affected or only some. The evaluative and centre-weighted metering are
transposed. Could all owners please check their Ixus 500 and report
whether or not it has this fault.

It is quite impossible to do a useful test unless one has much more data
about the number and size of metering zones and their weighting in the
evaluative mode relative to the centre weighted average mode. I would say
that it is quite possible under some conditions for the evaluative metering
to appear to be more centre weighted that the c/w average. Just accept
that Canon have probably got it right and get enough experience of the
camera to know how to meter to produce the sort of pictures you like.

--
Regards,
Baz

"Peter McKenzie \(remove 'nospam'\)" writes:
I have reported previously a fault in the metering of this camera. Please
check your camera so that we can assess whether all cameras are affected or
only some. The evaluative and centre-weighted metering are transposed. Could
all owners please check their Ixus 500 and report whether or not it has this
fault.

This is how to check:
Correct exposures would be: spot (more than) centre-weightedevaluative.
However, the faulty Ixus 500 gives spot"evaluative""centre-weighted." If
not sure you can read exposures from
downloaded photos into ZoomBrowser EX. (ie spot [lighter/more
exposure]than "evaluative etc

This is nonsense. Using spot meter mode will give you *more* exposure
than center-weighted mode if the area you measure in spot mode is darker
than average for the scene, but *less* exposure if the area is lighter
than average. You can't say anything about the relative exposure
without considering the image content.

If you want to test spot metering mode, put a grey card on a white
background, meter the grey card only, and see if the card ends up
approximately mid-grey in the captured image. Change to a black
background and see if the exposure remains the same (but the spot
metering area must be in the grey card only, with no background
included).

To test center-weighted mode, use the same setup, but now the overall
exposure should be affected by the black/white background. Grey on
black should get more exposure than grey on white, and the spot-metered
grey card should be between these two values.

Evaluative metering is even more complex. The camera meters a number of
points in the image, decides "what kind" of image it's looking at, and
guesses an exposure from that. Since the method isn't documented,
there's no objective test for whether it's working right other than "do
the pictures look ok?".

Or: light coloured oblong surrounded by darker area should be
spotcentre-weightedevaluative [spot setting darkest - evaluative
brightest] but "centre-weighted" is brightest - thus wrongly labelled.
means more than; means less than.

Again, this depends on image content, and whether the spot meter was
measuring the "light oblong" only.

This is important as the automatic mode will give wrongly exposed photos.
Canon will correct the fault if there is enough evidence that it is present
in all cameras. PLEASE CHECK

I suggest that you are just leaping to conclusions without doing any
sort of controlled tests, based on assumptions about the behaviour of
the metering modes that just aren't true. What does your camera do when
shooting the grey/white/black test subjects described above?

I have a S410, which is almost the same camera. I just shot a series of
3 photos of a greyish bag sitting on a darker grey carpet in the
hallway. The camera exposed all three at f/2.8 (wide open) with
different shutter speeds:

center-weighted 1/6
spot 1/4
evaluative 1/5

Looking at the image, the differences in exposure are pretty much
exactly as I'd expect. The spot meter mode rendered the portion of the
bag that I metered just about mid-grey in the digital image; the average
green-channel pixel value in the metered area is 127.4. That's as close
to "mid grey" as I'd expect any camera to get. The mean green pixel
value over the whole image is 133.8.

The center-weighted mode "saw" the white wall nearby and decreased the
exposure 2/3 stop. This gave an average green-channel pixel value of
114.8 measured over the whole image.

Evaluative metering gave an exposure halfway between these two
extremes, giving a mean green pixel value of 124.0. Subjectively, it
looks the best of the 3 exposures.

In other words, all of the exposures seem reasonable given what the
meter is supposed to be doing in each mode. For this subject,
my camera gives spot evaluative center-weighted, which is correct
for this subject.

How do you conclude that your 500 is faulty, given the same ordering of
meter results, without taking into account the subject matter? Why
don't you post some examples of your badly-exposed images where others
can look at them?

Dave

Apologies: my post omitted vital information and was unclear. Thanks to
those who replied: sorry for wasting time. I will repost with clear and
complete information.

Peter
"Dave Martindale" wrote in message
...
"Peter McKenzie \(remove 'nospam'\)" writes:
I have reported previously a fault in the metering of this camera. Please
check your camera so that we can assess whether all cameras are affected
or
only some. The evaluative and centre-weighted metering are transposed.
Could
all owners please check their Ixus 500 and report whether or not it has
this
fault.

This is how to check:
Correct exposures would be: spot (more than)
centre-weightedevaluative.
However, the faulty Ixus 500 gives spot"evaluative""centre-weighted."
If
not sure you can read exposures from
downloaded photos into ZoomBrowser EX. (ie spot [lighter/more
exposure]than "evaluative etc

This is nonsense. Using spot meter mode will give you *more* exposure
than center-weighted mode if the area you measure in spot mode is darker
than average for the scene, but *less* exposure if the area is lighter
than average. You can't say anything about the relative exposure
without considering the image content.

If you want to test spot metering mode, put a grey card on a white
background, meter the grey card only, and see if the card ends up
approximately mid-grey in the captured image. Change to a black
background and see if the exposure remains the same (but the spot
metering area must be in the grey card only, with no background
included).

To test center-weighted mode, use the same setup, but now the overall
exposure should be affected by the black/white background. Grey on
black should get more exposure than grey on white, and the spot-metered
grey card should be between these two values.

Evaluative metering is even more complex. The camera meters a number of
points in the image, decides "what kind" of image it's looking at, and
guesses an exposure from that. Since the method isn't documented,
there's no objective test for whether it's working right other than "do
the pictures look ok?".

Or: light coloured oblong surrounded by darker area should be
spotcentre-weightedevaluative [spot setting darkest - evaluative
brightest] but "centre-weighted" is brightest - thus wrongly labelled.
means more than; means less than.

Again, this depends on image content, and whether the spot meter was
measuring the "light oblong" only.

This is important as the automatic mode will give wrongly exposed photos.
Canon will correct the fault if there is enough evidence that it is
present
in all cameras. PLEASE CHECK

I suggest that you are just leaping to conclusions without doing any
sort of controlled tests, based on assumptions about the behaviour of
the metering modes that just aren't true. What does your camera do when
shooting the grey/white/black test subjects described above?

I have a S410, which is almost the same camera. I just shot a series of
3 photos of a greyish bag sitting on a darker grey carpet in the
hallway. The camera exposed all three at f/2.8 (wide open) with
different shutter speeds:

center-weighted 1/6
spot 1/4
evaluative 1/5

Looking at the image, the differences in exposure are pretty much
exactly as I'd expect. The spot meter mode rendered the portion of the
bag that I metered just about mid-grey in the digital image; the average
green-channel pixel value in the metered area is 127.4. That's as close
to "mid grey" as I'd expect any camera to get. The mean green pixel
value over the whole image is 133.8.

The center-weighted mode "saw" the white wall nearby and decreased the
exposure 2/3 stop. This gave an average green-channel pixel value of
114.8 measured over the whole image.

Evaluative metering gave an exposure halfway between these two
extremes, giving a mean green pixel value of 124.0. Subjectively, it
looks the best of the 3 exposures.

In other words, all of the exposures seem reasonable given what the
meter is supposed to be doing in each mode. For this subject,
my camera gives spot evaluative center-weighted, which is correct
for this subject.

How do you conclude that your 500 is faulty, given the same ordering of
meter results, without taking into account the subject matter? Why
don't you post some examples of your badly-exposed images where others
can look at them?

Dave