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Is it Auto ISO?On the D3...

Author	Post

Posted by Robert: Mon Jul 3rd, 2017 16:41

1^st Post

Or is it the lens, could it be a setting in the camera?

Camera: Nikon D3, no outlandish settings in camera, so far as I know... Set to Auto ISO and in Aperture priority mode. Weather was fine with bright (for UK) sunshine.

Lens: Nikkor 24-120 f4 ED VR.

All images are unprocessed NEF's.

I spent yesterday at a car hillclimb at Harewood in Yorkshire with Christopher. This afternoon while processing the images in Lightroom I was astounded to seem some radically colourised images. I had been using the Nikkor 300 f2.8 and the Nikkor 80-200 on my D3, all was normal until I got to one batch which had been taken with the Nikkor 24-120 f4.

I have set the D3 to auto ISO and it has been pretty well set at that since I first used it. However It rarely seems to move from ISO 800, I would have expected it to drop much lower in bright conditions. It's set to to max out at ISO1600, minimum shutter speed 1/60 Sec.

These images are grossly over saturated with blacked out shadows, massive contrast and total lack of shadow detail. I haven't attempted to process this images until I have some understanding what's going on.

Any ideas please.

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Robert.

Posted by Robert: Mon Jul 3rd, 2017 17:14

2^nd Post

This is what the same car should look like:

Taken with the D3 same settings, Lens Nikkor 80-200 f2.8 Trombone type.

Unprocessed image.

____________________
Robert.

Posted by Eric: Mon Jul 3rd, 2017 18:10

3^rd Post

Hi Robert
Surely it's just underexposed?

If the shot of the car on track is correct .....1/1250 @f10, then the same subject in the same lighting at f9 should only be 1/3 stop faster shutter speed to get the same exposure. The shot is 1/3200 at f9 when for same exposure it should have been 1/1600 @f9. So it's a stop underexposed for whatever reason.

Has the D3 been set to 'select' 1/3 stops?

Personally I have never trusted auto ISO in any program mode...only manual.

____________________
Eric

Posted by Robert: Tue Jul 4th, 2017 11:31

4^th Post

Thanks for that Eric, yes I usually have cameras set for 1/3 stop increments. I can see that two sets of variables, shutter speed AND auto ISO may have confused the system.

On the images with sky I should have expected some exposure error for the non sky parts of the image but those without sky have me stumped. I will stop using auto ISO with aperture priority and see if it fixes the problem. May switch to Manual with auto ISO? I like to control my DoF.

It's the garish saturation which hit me first, I had been using the 80-200 with no issues but as soon as I switched to the 24-120 all the car exposures are affected, it's only the image of the field which is OK.

I wonder if the strong reflections from the sunlight fooled the exposure control and caused it to under expose. I tried to position the camera so that I avoided the worst reflections of the sun but it was pretty strong.

I was a bit annoyed that having taken my time with the paddock shots they appear to be a disaster. Will have to see what I can recover...

____________________
Robert.

Posted by jk: Tue Jul 4th, 2017 12:41

5^th Post

I agree with Eric. I only used Auto-ISO in Manual exposure.

You have got D-Lighting enabled? I find that gives horrible results.

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Posted by Robert: Tue Jul 4th, 2017 13:06

6^th Post

'D' lighting not enabled. ;-)

Will go and do some processing, see if I can recover something from this mess! :'(

Thanks for the comments.

____________________
Robert.

Posted by Robert: Tue Jul 4th, 2017 16:12

7^th Post

Ok panic over!

Lightroom (ACR) has fixed the problem. I have got all the images back with acceptable tones. Thanks to the 'Auto' function which I haven't spotted before, it was a single click with minor tweaks to adjust to my taste.

This is the before processing state:

The camera settings:

And after 'Auto' exposure adjustment:

That's pretty good, to my eye anyway. I need to stop using two exposure variables, but I still wonder why it only affected the exposures made with the 24-120 lens all the other exposures made with the 300- f2.8 and 80-200 f2.8 were pretty near perfect straight off the card, just needed to tweak the black and white points and maybe the highlight/shadows a tad.

At least they could be salvaged.

____________________
Robert.

Posted by Eric: Wed Jul 5th, 2017 03:33

8^th Post

The other point is that on the image examples you gave there is the obvious difference of 31mm plays 200mm. The mere fact you are using a wide angle lens may well influence how the camera meters to some degree. Never the less, the D3 is such a capable camera, I do feel the exposure difference is more likely to be a function of the different lenses. Which is right, is another question.

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Eric

Posted by Iain: Thu Jul 6th, 2017 09:46

9^th Post

Robert, Check your settings for max and min auto ISO as this my be why it never goes below 800.

Posted by novicius: Sat Aug 5th, 2017 22:52

10^th Post

That is what active-D lighting should take care of, it does both in my D3S /X which I most often have on Auto Actice.D , `tho they tend to over expose 1/3 to 1/2 stop...

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