I think you found the error here but I certainly can't explain where it
came from. The information was right in front of me and I wasn't even
seeing it. I just went through and did a quick check of the data in all
of the other shots.
Interestingly enough, I found an image that's almost exactly the same
scene as #367 but taken a few minutes later with a few different people
in it. The exposure is quite normal. That should have been my clue that
something went very wrong with #367.
I shot about 75 images that day and #367 is the only one where the EXIF
data shows "Exposure Mode: Manual" I certainly don't remember changing
the mode for just this frame, then changing it back. All the frames
before and after are shown as aperture priority just as I remember
setting the camera before I started shooting.
As you probably know, the viewfinder display is different when in manual
mode. The "A" auto mode annunciator disappears and is replaced with an
"M" and a bar graph to use in setting exposure. I have to believe I
would have noticed, but who knows, I am old and all those flashing
lights in the viewfinder may have distracted me... :)
But honestly, if I were in customer service, I'd write this one off to
"operator error" no matter how many times the operator tells me it
wasn't so...
No matter, it's obvious information is there for future reference. I
need to look at it in a more analytic manner from now on.
--
Jim
* Your comment about EXIF ISO data - I see it using Nikon Capture or
Nikon View to view the file. I don't see anything about flash mode other
than "Flash Sync Mode: Not Attached" though. It seems different software
shows a different part of the data set?
Another funny thing. I have a file a friend sent a file from her D100
that's also massively underexposed and I just checked it. It clearly
shows "Programmed Auto" for the mode, but most of the other data is
missing. I'm going to see if I can get the original file and take a look
at it...
Moose wrote:
> Lots of interesting posts on this, much info.
>
> But lets get down to it.
>
> In 366, in spite of being given orders to overexpose slightly and having
> a large expanse of bright sky, the camera did an excellent job of
> exposing for the main subject.
>
> In 367, it badly underexposes a really ordinary scene. There is only one
> sensible conclusion. Something in not working properly. Ruminations
> about matrix aside, I can't believe that any modern exposure system
> could miss this badly. This is just not an exotic lighting situation.
>
> So what could be wrong?
>
> Lens? You say a N*** zoom, I assume the same for each pic. EXIF contains
> focal length, maximum available f-stop and exposure f-stop. So it would
> appear to be a proper lens for the camera, at least it communicates with
> it. Both shots were at f5.6. So it doesn't seem likely that it is the
> lens, but the lens is older than the camera. Confirmation through uae of
> another lens and/or results with this lens on another camera would confirm.
>
> Camera? There are a couple of clues in the EXIF.
> #366: Exposure Time 1/60 , F-stop f5.6, Exposure Program Aperture
> priority - Flash undefined value
> #367: Exposure Time 1/250, F-stop f5.6, Exposure Program Manual - Flash
> did not fire
>
> So in the same light, but without a lot of bright sky in the background
> and at the same aperture, the camera selects a shutter speed 2 stops
> faster! Now why would it do that?
>
> - Well, the EXIF says it didn't! It says it was under Manual control for
> the poor exposure. So either you changed the setting, perhaps
> inadvertently, or the camera does so on it's own and needs repair.
>
> - Because the exposure system knew flash would be needed? Notice that in
> the Flash section of the EXIF for 366 says 'undefined value', while in
> 367, it says 'did not fire' That sounds to me like it was expected or
> needed to fire but didn't. Now you say it was set for no flash. So it is
> possible that the 'did not fire' is a comment that flash was needed, but
> not selected. Of course the flash sync is only rated to 1/180 on the
> D100, so a manually selected speed of 1/250 probably prevents the flash
> from firing anyway.
>
> So what can be concluded from the samples? It is possible that there is
> something wrong with the camera, but that can't be concluded from these
> samples. Further careful testing is required to be sure whether the
> change of mode from AP to Manual was an external or an internal event.
> If external, it appears the camera did as instructed; it took an
> underexposed picture. I doubt if these pics will convince Nikon Service
> there is a problem, if they read the EXIFs, without further clarity on
> settings.
>
> Moose
>
> *Also, what kind of camera doesn't show the iso setting in the EXIF??
>
>
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