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Serious overexposure issue with my A700

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Nick Name

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On my last two summer vacations in Spain and Greece I encountered a an issue of my A700. Some pics taken in very bright sun are way overexposured although there should be no reason to do that (like extreme contrast). I usually take most pics in A-mode.
The following pic is taken at 1/200 and f 5.6, lens is Sigma 10-20 mm.
Quality is C-Raw developped with ACR 4.5, no adjustments made, only resized.

For my normal photographic understanding the pic should have been underexposed, not overexposed.
Any ideas?



Nick
 
What 'film' speed have you set the camera to?

John
--

A700+grip,7D+grip,KM 50mm F1.4,KM 28mm F2, KM 50mm F2.8 macro, KM 70-210 F4,KM 135 F2.8,KM 28-85,KM 75-300,KM 28-135 F4-4.5,Sigma 100-300 F4 APO DG, KM 5600HS(D), KM 3600HS(D)
 
Hmm, it was even in the display way too bright and I've been taken some pics c-Raw+jpeg. The jpeg turned out overexpoed, too. I don't think it's the software...

Nick
 
Maybe your lens is not stopping down? Oily aperture?
Nick Name said:
On my last two summer vacations in Spain and Greece I encountered a
an issue of my A700. Some pics taken in very bright sun are way
overexposured although there should be no reason to do that (like
extreme contrast). I usually take most pics in A-mode.
The following pic is taken at 1/200 and f 5.6, lens is Sigma 10-20 mm.
Quality is C-Raw developped with ACR 4.5, no adjustments made, only
resized.
For my normal photographic understanding the pic should have been
underexposed, not overexposed.
Any ideas?



Nick
Click to expand...
--
Dumont - http://www.pbase.com/dumont - For equipment see profile.

 
I know that in lightroom, A700 pics need a 2/3-1 stop negative exposure comp to be correct. This is a well known problem with lightroom. Maybe it's the case in your ACR as well?
 
From the "recovered" picture it doesn't look as though the scene was too bright - but: Remember that the camera's meter only works properly inside a certain EV range - if the scene is too bright (like shooting into the sun f.e.) the meter might not work properly anymore.
 
I have two lenses that do not work very well with the a700 metering/lens feedback, they both overexpose. One is the 11-18 Tamron and the other the Bigma. However they do it in a predictable way so dialling in some compensation is an easy fix.

Try another lens and clean the contacts carefully so you can determine whether it is the camera.

waveney
--
Next-door to World of Adventure
 
Had it been really overexposed, there wouldn't be that much of highlight recovery possible.

Yet, if you insist the accompanying JPEG was also overblown, it may mean there's a problem with the metadata... And that's still a problem though, not as serious as real overexposure.
 
My version of ACR gives me normally good results even in difficult situations.

ck3, I'm afraid you gave the best answer so far, the overexposure is only at very bright sun conditions. If it's not really bright, the exposures are perfect.

Hmm, is it possible that the maximum sensitivity of the metering device has a big variance across the production series?

Nick
 
Looking at the recovered Raw picture, it looks perfectly exposed. There is very slight clipping on the highlights, so it appears that the camera exposed to maximum right, which is correct. Had the exposure been reduced then the shadows would have looked muddy.

Did you use any creative styles by any chance? That might explain the overexposed Jpeg.
Nick Name said:
after some adjustments it came out acceptable, but you know that's
not the way it should be.
Click to expand...
I don't understand what you mean by this. RAW pictures always require some processing, especially contrast or curves adjustment.

--
FEM2008
 
FEM2008, I know raws are made to tweak them to get the maximum. However a raw should deliver a resonable base to start from.

This for example is a picture with a lighting situation that is not easy, but the A700 was exposing perfectly.



Nick
 
I share your frustration in trying to figure out what is going on. However, understanding 'exposing-to-the-right' might help explain what the camera is trying to do here (especially evident since the V4 firmware). If you search on this forum, you will find a link to an excellent article on exposing to the right.

This example is little different. The dynamic range of this photo is greater. You have more areas with true white in the photo, so the camera is forced to back off the exposure to prevent sever clipping. It just happens that the amount of highlight balanced out the deep shadows, so it looks like the photo was exposed correctly in the first place. Juts luck in this photo IMO.

Again, in the last 2 examples, I don't see strong evidence that the camera is really overexposing.

FEM2008
 
FEM2008 said:
I share your frustration in trying to figure out what is going on.
However, understanding 'exposing-to-the-right' might help explain
what the camera is trying to do here (especially evident since the V4
firmware). If you search on this forum, you will find a link to an
excellent article on exposing to the right.
Click to expand...
The examples posted do NOT show ETTR - the highlights are blown out and I doubt that the details could be recovered with JPEGs (and even the recovered highlights in the raw example suggest that there has been some color clipping - the sky doesn't look natural). BTW it would be a strange move by Sony to totally change the metering algorithm from 18% grey (or whatever the current number is) to ETTR with a FW update without telling its users it did so :-). I still guess that the image contrast was too high for the meter and it got confused, center weighted metering might have helped in that situation.
 
ck3 said:
The examples posted do NOT show ETTR - the highlights are blown out
and I doubt that the details could be recovered with JPEGs
Click to expand...
I was talking strictly about the raw images and not the jpegs.
Member said:
(and even
the recovered highlights in the raw example suggest that there has
been some color clipping - the sky doesn't look natural). BTW it
would be a strange move by Sony to totally change the metering
algorithm from 18% grey (or whatever the current number is) to ETTR
with a FW update without telling its users it did so :-). I still
guess that the image contrast was too high for the meter and it got
confused, center weighted metering might have helped in that
situation.
Click to expand...
Check out DK's forum that there is evidence that the new firmware is closer to the Nikon 300 in exposure, which exposes more to the right to improve noise performance. I don't think manufacturers ever tell you 100% of what has been updated or changed.

ACR also tends to convert the A700 raw images slightly overexposed with some color clipping, especially in the red channel. The weird sky color could be due to the choices made during processing. I twould be nice to try the conversion using another program.

I think we both would agree that, in the first example, the total EV range covered is pretty wide, and it would be pretty tough not to clip anything at all.

--
FEM2008
 
FEM2008 said:
ck3 said:
The examples posted do NOT show ETTR - the highlights are blown out
and I doubt that the details could be recovered with JPEGs
Click to expand...
I was talking strictly about the raw images and not the jpegs.
Click to expand...
If the camera exposes in such a way that the jpgs are not usable anymore, something is wrong with the metering :-)
FEM2008 said:
FEM2008 said:
(and even
the recovered highlights in the raw example suggest that there has
been some color clipping - the sky doesn't look natural). BTW it
would be a strange move by Sony to totally change the metering
algorithm from 18% grey (or whatever the current number is) to ETTR
with a FW update without telling its users it did so :-). I still
guess that the image contrast was too high for the meter and it got
confused, center weighted metering might have helped in that
situation.
Click to expand...
Check out DK's forum that there is evidence that the new firmware is
closer to the Nikon 300 in exposure, which exposes more to the right
to improve noise performance.
Click to expand...
The exposure difference between the Nikon and the Sony is less than 1 EV IIRC (and it is still present after FW 4). The overexposure in the OPs pictures to my eyes is more than that.
FEM2008 said:
I don't think manufacturers ever tell
you 100% of what has been updated or changed.

ACR also tends to convert the A700 raw images slightly overexposed
with some color clipping, especially in the red channel.
The weird
sky color could be due to the choices made during processing. I
twould be nice to try the conversion using another program.
Click to expand...
The OP said that the jpeg looked the same, so it's not the conversion (and while ACR set to its default settings tends to push the exposure it's nowhere near as bad as in this example).
FEM2008 said:
I think we both would agree that, in the first example, the total EV
range covered is pretty wide, and it would be pretty tough not to
clip anything at all.
Click to expand...
This might well be the case, but still I don't think that this is a case of some clipped highlights - to me this is a case of severe overexposure: there aren't any dark tones in the image - the shadows have been shifted to the midtones - there would have been (considerably) more room for the highlights had the exposure been shifted to the left.

But I've got a new theory: it was obviously hot, Nick Name's hands were sweaty and by accident his finger slipped and pressed the AEL-button ;-) (to the OP - I'm just kidding).

Carsten
 
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