Auto ISO

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donkey_kong

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I was playing around with my D3100 yesterday and noticed that on a number of pictures it was over-exposed by around 0.3 or 0.7 stops. This coincided with changing my setting to auto-ISO. However, I should have switched it back to check if it definately was this function that was affecting it. I don't think it should, but should this have this effect?
 
If you are in any mode that the camera sets exposure P, A or S mode, Auto-ISO setting won't affect the exposure. The camera meters and takes the shot all the same.

(great name, btw)
 
I found (and also read in several places) that nikon jumped up the ISO range very quickly and didnt really drop down easily, so once the upper limit was set - it would pretty much sit there regardless of available light.
 
May want to check which metering mode you are using and check if it's suitable for what you're trying to shoot.
 
donkey_kong said:
I was playing around with my D3100 yesterday and noticed that on a number of pictures it was over-exposed by around 0.3 or 0.7 stops. This coincided with changing my setting to auto-ISO. However, I should have switched it back to check if it definately was this function that was affecting it. I don't think it should, but should this have this effect?
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If it's exactly +0.3 or +0.7, confirmed by Exif, then it sounds like you've accidentally adjusted the exposure compensation.
 
sk66 said:
Or turned on bracketing... But it's probably metering mode/method.
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This is what you're looking for :)

Also, IIRC, You can adjust the range of ISO from within the settings. Sometimes it's minimum/maximum but don't call me on it as I can't remember if thats in the D3100 or in higher models.. or it might even be a canon.. :bonk:

Have a gander through the menu's and see if you can find Auto ISO range or something like that :)
 
Thanks for the replies. It's definately not exposure compensation, as I specifically checked this first. The D3100 doesn't have a bracketing option so it definately can't be that. The metering mode used was matrix.

I think rather than over-exposured as stated in my original post, some areas were over-exposed. There was a white muslin over the subjects shoulder and a patterned bright wall behind. Both these areas were over-exposed but the rest of the pictured seemed to be okay. I will post some pictures later for everyone to see what I mean.
 
Depending on the metering type, the camera might be metering for what is in the center of the image or may be trying to meter for the overall image and not quite getting it right.

Do you know what metering type it was using?
 
Phal said:
Depending on the metering type, the camera might be metering for what is in the center of the image or may be trying to meter for the overall image and not quite getting it right.

Do you know what metering type it was using?
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I have a feeling it was matrix (or evaluative) based on the post above yours :)

The camera would have exposed based on an evaluation across whole image so would need to see the whole image to determine whether the camera had done a good job or not or whether you should have change metering modes if the scenario was throwing the camera for some reason (too big a mix of light and dark and camera not knowing what you wanted)
 
donkey_kong said:
The metering mode used was matrix.
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This is your "problem" then. Obviously, there wasn't enough white in the scene to cause the exposure to be reduced enough to keep it from blowing out... Pretty normal really.

Matrix metering is the mode I use the least...as in almost never.
 
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