Problem with new D5100 found..

I was having odd exposure problems with my new camera. I first noticed it do some macro shooting outside. I was focus bracketing some shots and noticed the exposure from shot to shot was slightly different. Not a -lot- but maybe 1/3 to 1/2 of a stop from the darkest to the lightest. It was very noticeable. Nothing that couldn't be "fixed" in PP but this shouldn't be happening. This was using a tamron 90mm lens and at first thought maybe was something flakey with the matrix metering and a 3rd party lens. I was shooting in A mode so switched to center weighted and same thing. I then tested some more and noticed I was getting inconsistent exposures from  f8-1/50 to f11-1/25 even in M mode, which should look exactly the same.

So I setup the camera and started testing equal exposure pairs starting at F4 and working down to f16 with auto ISO turned off and ISO set at 800. I then made a group of 5 exposures at 1/15. All in manual mode. I did this with two different lenses, the other a nikkor 16-85. The results? The exposures were all over the place even though they should be the same! The only thing I can figure is there was something mechanically wrong with the shutter. Especially since 5 shots in M mode one right after the other without changing shutter speed or F stop didn't have consistent exposure.

So I take the camera back (this is a pro camera shop) and the first person I show these test shots to looks at me like I am speaking a foreign language. They didn't seem to grasp that a shot at f8-1/50 and f/11-1/25 should be the same exposure. They want to "reset the camera to default settings and shoot in auto" to test it. *sigh* I start to get a bit peeved and show her 5 shots all at the same setting in M that have different exposures and they start talking about the metering modes again. So I ask to speak to someone else. The next guy seems to understand what I am saying and finally after playing with the camera, he concedes it's defective.

I guess my point is, if you are having weird metering problems, maybe do some "back to basics" testing. The meter can be the most accurate thing ever made but if the shutter or some mechanical part isn't working right or isn't consistent, it's not gonna give good results.

After using the D5100 for a week, I did decide to upgrade to a d7000, mainly so my old MF 300mm F2.8 ed nikkor will meter on it. I didn't realize the D5100 wouldn't when I bought it. It does have a lot of nice features and was worth the extra $$.

--
Stacey

... will all say the problem must be you since in their eyes it is not possible for a Nikon product to be faulty.

I have an ancient D70 and a much newer D300, both of which are superb. Make sure you test your new D7000 properly, focus charts, inclined rulers, serried ranks of AA batteries etc. lest you are jumping out of the frying pan into the fire.

David

Very Interesting.  Thanks for bringing it up. It's the first time this has been reported.

First, Matrix metering can vary a bit if focus point changes or any of the other things that go into Matrix.  Second...as it happens in manual exposure mode as well, I have seen this happen with one lens due to the aperture blades sticking.  Third, if you had ADL (active D-Lighting) on...it can happen as well. With out being able to examine EXIF from examples...I'm thinking you had ADL "on" or perhaps a sticking aperture blade.

Fourth, could certainly be the camera as well...have seen dust do this (very rare and affected focus) and even a ground short perhaps.  If you have an example of this...in manual exposure mode with two shot of same settings showing different exposure...that would be a great help to us if you would share.

Please keep us updated on the new body and Good Luck

What did the guy do in the store (you said he was "playing with it") to decide the D5100 was defective?

Was that based on your images, or did he do something with the camera to decide this?

An aside: if you traded it in for the upgrade, hopefully you got all your $$$ back and they sent it to Nikon for refurbishing.

ADL was def off and it did this with two different lenses so likely isn't two lenses with problems. Sorry but when I got my new body I formatted the memory card so don't have "proof" and I don't need any. I'm not trying to say "nikon sucks" but just to warn people not to overlook the basics when if they have an exposure problem or always assume "I am doing something wrong".

And on ADL assumption, something would be very broken with ADL if the same exact scene with the same lighting and settings produced different results. At least I would think so.

BTW I did the same tests with the new body/same lenses and the exposures look reasonably close. repeated same exposures are spot on. You might try doing them yourself and realize no camera achieves perfection in "exposure matched pairs" that I have ever tested be it a film or digital. It's just close enough in practice. This first body wasn't.

--
Stacey

He set the camera on manual, checked through the menu for other "wrong" settings I suppose and then started shooting 3-4 bursts and looking at them. He saw the same inconsistent exposures and after a few minutes said "yeah there is something wrong".

And yes I got all my money back and I assume they will return it to nikon, I don't really care what they do with it

--
Stacey

I have and honestly most cameras I have owned had something that needed to be "worked around". As long as it's consistent, I can live with a meter that need +.5EV compensation etc. It's problems like this that you end up just chasing your tail trying to deal with.

Anyway so far in testing this new body seems to work fine.

--
Stacey

Good. That's easy. I never noticed a similar problem on my D5100, but for the heck of it I just checked it.

From the what you described, it sounds like inconsistent shutter speeds to me as well. It would be hard to pick out, but you'd expect that the variance would be greatest within a certain range, not at the slowest and not at the fastest.

--
http://1000wordpics.blogspot.com

Not looking for any "proof".  Was just hoping to see the examples to study so that what might be learned could be passed on to anyone else in the future. In that way, it's easier to help the next person as this is a first...as far as I can tell.

Again, have not seen this so anxious to learn the cause. Please keep us updated if you find out.

It should stay the same (assuming tripod and perfect constant light for a scene match) as long as nothing changes like focal length..meter..base Iso...or picture control settings.  A few other things can do it but with ADL "off"...obviously not it.  One note:  were the shots CDAF (LiveView perhaps)  LCD brightness can affect it in this way as the camera will up the JPEG/Raw brightness setting to match what is seen on the LCD screen.  This is normally only a player though during outside bright daylight shots.  Another reason I was hoping to see the examples...Love a puzzle.

When you say reasonably close...they should be the same. How are you comparing?

If I use a tripod and the light does not change....my exposures are indeed matched "perfectly".  Here is an example used to show the affects of a filter (one pic has a filter on). All the shots were taken in sequence, of a test card. There's no reason they would not be exposure matched. Are you saying the light and scene wasn't actually matched in your original posts case? Good Luck going forward. Glad it has worked out.



I should be more specific.

I handheld 3 or 4 shots in M mode, manual focus lens, and looked at the images and the histograms. The images on the LCD looked identical to me, the histograms showed extremely minor differences in a few of the vertical bars.

no live view. (ewww)

What I mean was a sequence of shots, on a tripod of a simple scene (kitchen counter) with fixed lighting. Set on manual focus and M shutter speed (The really bad ones were at 1/15) and aperture, with auto iso/ADL etc off. No changes other than I pressed the shutter 3 times without ever lifting past "half press". The "brightness" on the histogram and visibly on the monitor changed between shots. Given it happened on 2 different lenses, I have to assume for some reason the shutter isn't working right. Defects do happen. It likely isn't a problem with this model, more a problem with my sample.

The other test I did was shot "exposure pairs" i.e. F4-1/60, F5.6 -1/30, F8-1/15 f11-1/8. f16-1/4 and look at the histograms and visible density/brightness (Maybe this is a film term?) on a computer monitor. I would assume they should be very close, at least that's what I was taught when I learned about photography 35 years ago :P. On my E1 and this D7000 they are reasonably close, only a very small variation between shots. And on both they seem to error most near wide open, both are brighter on the F4 shot, the rest down to f16 were very close to each other. On the D5100 they varied from lightest to darkest almost 1/2 a stop. That's not acceptable for a modern camera.

The point of my post wasn't that the D5100 has a design flaw but that bad samples of a good camera do happen and it might not be a problem with the metering or even the user but simply a mechanical problem with the camera.

--
Stacey

Right, that is what my new one does too and is what you would expect. Now try f4 to f16 in A mode and in manual setting equal exposures and see if they still look close. My new camera does, that other didn't.

--
Stacey

Ah, now it is much clearer, Thank you. One note....this has come up before. It was due to compact florescent lighting and not a true exposure issue but a thing wiith the lighting and the way new bulbs cycle. Happened in a gym as well with new lighting installed for a new season. Bur some pics look brighter and other look yellow (light changes between the camera having metered the scene and exposure being recorded) .  Probably not the case here as I assume you have tested well in the same kitchen with same lighting.  Just letting folks know. In that case it looked more of a WB issue but you had to check the EXIF to really see what was happening. Thanks for the additional update.

Now I see what you mean by "exposure pairs". I misunderstood, sorry.  Yes, there will be some variance (should be very small as that's what Program exposure mode is all about)....wide vs stopped down and also lens to lens.  It's a tolerance issue, is my understanding, but it should be consistent....as in all f4 shots look the same and all f16 shots look the same. I do not know the tolerances with the D5100 aperture mechanism but again all f2 should look the same as all f2.  You might also try the D5100 in Program exposure mode and see in the 1/2 stop dif persists.

Agreed.  Just trying to learn more.

The D5100 has auto bracketing, item e2 on the menu. could that have been turned on. That would give you three different exposures, even in manual mode.

I don't think it will in manual mode unless "auto-ISO" is enabled.  It will only make the meter reading in the viewfinder change and not actually change aperture or shutter speed. I could be wrong though.

Stacey, just something you might want to check. It is possible to accidentally set the camera to bracket the exposure automatically. That is, depending on your bracket compensation, you could take six shots and have one under by .5, one on, one over by .5 . . . and then one under by .5, one on, and on over by .5 . . . forever - and frustrating the hell out of anyone experiencing it! The camera, depending on setting, could tweak the shutter speed, f stop, or both. Turn the camera off and then on again and this "problem" repeats. Now go to your manual and change this. Of course, I am just guessing (based on a ton of experience).

Most clerks at most ANY camera shop are ill prepared to offer sage advice. Sad, but VERY true.
--
Steve Bingham
www.dustylens.com
www.ghost-town-photography.com

As you want to use it with manual lenses, it seems you got the better camera anyway. You got a bigger and better focus screen and the rangefinder on the D7000 is 'reported' to work even better than the D300 one, for manual focus.

I get my D5000 focused ok in manual, but I am going to upgrade for a bigger focus screen and updated sensor at some point. The D7000 or its replacement  (or the D700 used) will be options.

Seems like the best choice for you at this time.

--
.....Just from an amateur......''Sometimes it's to your advantage for people to think you're crazy.”

That's all true but it would report it as different apertures, shutter-speed, and/or ISO. You may certainly be right as OP doesn't explain if his tests showed different actual settings of those parameters.  So wish we had just one example....the EXIF would have showed if bracketing was on.

What camera do you have, if it has auto bracketing test it out. If you have auto set to 3 pictures at norm -1 +1, take first picture at f2.8 you are at norm, change to f 22. picture will be at -1. turn off auto bracket, take picture at f22, it will be brighter that the first.