Author Topic: wrong exposure when pressing shutter-release half way and recomposing  (Read 996 times)

Matthew Currie

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OK, I snuck out my wife's D7200, and set it up as per your post (and also remembered to turn off C1).  I'm using the 18-140 lens, set at F8.  I aim it at a light fixture, and get 1/500 second at ISO 220.  Holding the button down, I aim at a very dark spot, and get 1/40 at ISO 1600, which is still way underexposed.  I do this again, aiming at the light fixture, and this time get 1/800 at ISO 200 (slightly different position, I think, since focus priority doesn't like the blurry bulb).  This time I re-aim at a wall that is not so dark, and get 1/250 at ISO 720.  But despite the change, it's still underexposed.  If I simply fire at the wall without first aiming at the light fixture, I get a well exposed picture at 1/25  and ISO 1600.

Trying this several times, I find that the issue is not entirely consistent, but it is indeed doing what you say it is.  If you take a bright picture first, it underexposes the second,  usually without changing ISO.  The first time I tried this it changed the ISO, but on subsequent tries it does not.

I tried the same thing with the D7100.  It performed perfectly, giving a correct exposure when recomposing from a bright light to a dark corner.

The D7200 works correctly if I use your settings but change to center weighted metering. Put it back to matrix and it fails again.

I must say this is a strange one.  I think it's a glitch in the software of the D7200, but it's not in yours alone.

Now I hope I remember what settings to restore on my wife's camera!     :-X




David H. Hartman

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Now I hope I remember what settings to restore on my wife's camera!     :-X

There is a save/load settings feature found on my D300s, D800 and D850. I place save/load settings in My Menu for easy access. I save my defaults settings and then take the memory card to a computer and card reader. The settings files end in *.bin. I save the bin files to my "pictures" directory on my computer. Before returning the memory card to my camera I write protect the bin file using "properties" or "get info" so I won't accidentally over-wright my settings.

I don't format my memory cards often but when I do I restore my settings file from my computer to the memory card. I only write protect the bin file on the primary memory card. If I want to save a new default settings file in the field I remove the primary memory card and save the new settings to the secondary card.

This procedure is a bit fiddly but it saves my ass from time to time. How I hated the lack of such a feature in my D2H.

Dave
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Matthew Currie

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Fortunately I actually remember the settings, because we both have such similar cameras and our differences are minor (she doesn't like back button focusing).

While on the subject, I should add that I played a little more with this odd issue.  Using thrillmetoo's settings, it consistently underexposes in matrix mode and any of the P,S,A and M modes, though it seems sometimes to work OK in manual mode. The amount of error is not consistent. It sometimes alters ISO but not enough, sometimes some other setting but not enough. 

It appears to be a matrix metering issue.  It behaves the same in AFC, and seems not to vary with starting ISO, ISO high limit, or shutter speed limit.

David H. Hartman

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I begin to wonder if I should bring out my Minolta Flash Meter III and Pentax Digital Spotmeter?

Dave
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Oh no, must be the season of the witch!

Matthew Currie

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By the way, I tried the same (or similar) settings on a D3200, and like the D7100 it performed correctly.  It seems to be unique to the D7200 in matrix mode, that AE acts as if held (or kind of half-held) even when it is not.

David H. Hartman

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By the way, I tried the same (or similar) settings on a D3200, and like the D7100 it performed correctly.  It seems to be unique to the D7200 in matrix mode, that AE acts as if held (or kind of half-held) even when it is not.

Do other Nikon D7200 owners report the same problem? If so does Nikon know about this? Are they going to get off their asses and fix it?

Dave

Should I have been a bit more delicate in my writing in the last sentence?
Beatniks are out to make it rich
Oh no, must be the season of the witch!

Matthew Currie

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I suspect that few Nikon owners are aware of this, as it's a fairly infrequent issue.  The D7100 and D3200 don't do it, but if they did, I would never come across it because it does not occur with BBF. On the D3200 and its ilk,  you must then enable shutter button AE lock anyway,  or be left with none at all.  My wife never encountered it, because she rarely recomposes and the problem is only obvious if the change of exposure is pretty extreme.

It's a good question, though, and perhaps I should write to Nikon about it somehow.  I don't hold out much hope for another firmware update, though, given the age of the camera.  I have wished in vain for years for a D7100 update that would re-enable trap focusing, which has returned on the D7200, so I know it can be done.

e.t.a.  So I just emailed Nikon customer support.   Will see what comes of that.  I would not keep fingers crossed, though, as permanent cramping could ensue.

thrillmetoo

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Thanks for the effort you've taken so far. When this issue stays unanswered, I think I'll go back to center weighted measuring, that I used for countless years. Though not always as predictable, I feel matrix metering prevents blown out spots more than center weighted in shots that I can not be repeated.

Matthew Currie

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Center weighted seems to work fine, but I might also suggest back button focusing.  It takes some getting used to but has considerable advantages, I think.  And this too eliminates the problem, since you no longer need to hold focus with the shutter button.  On the D7200, you can either enable shutter button AEL. or assign it to another button.  Some years ago in Alaska, where the scene was essentially monochromatic and high in contrast, I found it convenient to use spot metering and BBF.  First decide where to focus, do it and let go; then decide where to get the right exposure, hold down the shutter button, and then recompose and shoot.   If you don't need to select a separate AE point,  just skip the middle step, and it will occur when you shoot.


thrillmetoo

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When back button focusing became a thing, I thought it would blow over as any other hype. I thought (think?) along the lines of 'don't fix what ain't broken'. And the fear of missing shots prevented me from giving it a go.

Matthew Currie

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I found I got used to it very quickly, and I don't think it causes me to miss shots any more.

I would, however, suggest trying it out when you're near home and not taking critical shots for a while, as it does require the formation of a new habit.