Why is my bracketing doing this?

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Slipperman

Senior Member
using my D750, i recently took a bunch of 7-exposure bracketed series of photos in AP mode. when i looked at the exposure info in ViewNX 2 for each of the series, they didn't look right. for instance, for 7 exposures i would expect the EV values to be as follows: -3, -2, -1, 0, +1, +2, +3. but instead i got -4, -3, -2, -1, 0, +1, +2. why more dark than light?
also using auto ISO, the ISO values for 0, +1 and +2 exposures were cranked up to 500 when i wouldn't think they would be (it was a bright sunny day). for the negative EV's, the ISO's were right around where i'd expect them to be (100, 140, etc). for completeness, here's the exposure info for 1 series of 7..

ISO 100, 1/4000, f10, -4 EV
100, 1/4000, f10, -3
140, 1/4000, f10, -2
280 (?), 1/4000, f10, -1
500 (?), 1/3200, f10, 0
500, 1/1600, f10, +1
500, 1/800, f10, +2

is it possible there's another camera setting that could cause this?
posting this here because i'm not sure this is D750 specific.
 
P

PapaST

Senior Member
this is a shot in the dark, but is there a chance that your exposure compensation is set to -1 and maybe that's why it's skewing the values to under expose rather than equally over and under expose?
 
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Slipperman

Senior Member
PapaST said:
this is a shot in the dark, but is there a chance that your exposure compensation is set to -1 and maybe that's why it's skewing the values to under expose rather than equally over and under expose?
Click to expand...
yup, didn't even think of that. still not used to the new camera - i had to actually look for the button. still not sure about the ISO changes though.
 
Vixen

Vixen

Senior Member
You are using AP, which means when the camera is changing settings to make the under & over exposed images it can only alter ISO and shutter speed to achieve the desired results, which is why you are getting the settings you are getting.
Optimally, you should be in M when shooting bracketed shots
 
Marcel

Marcel

Happily retired
Staff member
Super Mod
Vixen said:
You are using AP, which means when the camera is changing settings to make the under & over exposed images it can only alter ISO and shutter speed to achieve the desired results, which is why you are getting the settings you are getting.
Optimally, you should be in M when shooting bracketed shots
Click to expand...

From what I've read, the recommended setting for exposure bracketing is Aperture priority. This is to prevent the depth of field to be different from one shot to the next. But I think auto-iso should be turned off.
 
Vixen

Vixen

Senior Member
Marcel said:
From what I've read, the recommended setting for exposure bracketing is Aperture priority. This is to prevent the depth of field to be different from one shot to the next. But I think auto-iso should be turned off.
Click to expand...

I can't comment on the specific camera but on my D7100 I use bracketing lots...and I mean LOTS coz I love HDR.
I use M
The only thing that changes to achieve my 5 bracketed shots is shutter speed. Doesn't matter if I am in strong sunlight or deep shade. I make sure my 0 shot is properly exposed.

So yeah, it is probably a combination of AF & auto ISO that caused the problem
 
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S

Slipperman

Senior Member
Vixen said:
I can't comment on the specific camera but on my D7100 I use bracketing lots...and I mean LOTS coz I love HDR.
I use M
The only thing that changes to achieve my 5 bracketed shots is shutter speed. Doesn't matter if I am in strong sunlight or deep shade. I make sure my 0 shot is properly exposed.

So yeah, it is probably a combination of AF & auto ISO that caused the problem
Click to expand...
i saw this too on my 5100. summer '13 i was out of work and had plenty of time on my hands so i would go out and shoot often. at that time i used Manual and whenever i used bracketing, i noticed it acted as though i was in AP mode because just as you said, only the shutter speed changed. i'll have to try the same on my 750 and see if the ISO changes as well.
 
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