Another strange bug with D4, possibly D800!?!?

Started Feb 5, 2013 | Discussions
OP Roland Schulz Contributing Member • Posts: 546
Workaround...

I found a workaround for this/my method:

1. Focus the camera pressing the shutter to the first step.

2. Let all buttons go.

3. Recompose.

4. Hold the AF-ON button and take the picture, so focus isn´t aquired again but exposure is taken correctly for the new scene.

Works for me, but still wondering what´s going on when holding the AF-ON while recomposing.

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Nikon D3 Sony a6500
lock Veteran Member • Posts: 6,202
This is exactly as expected!
1

If you do not lock the exposure, the total scene will be measured with a specific attention to the old spot you focussed on when you press the AF-ON to achieve a focus lock. But, if you move the scene (recompose) and the scene becomes darker, the metering will change only to some extent but because the value metered unde the original focus point still influences the calculated aperture and shutter speed. This chance could very well be rather limited. However, once you let go the button, the camera now evaluates the amount of light under the current focus point in the new scene. That area may be way darker (or brighter), hence changing the values even more.

You can test this by changing the scene using your method of holfing the focus and recomposing. Go from a bright scene with a bright object under focus to a dark scene with a dark subject (without refocussing). You will see a lengthening of the shutter speed while recomposing but holding the af-on button and the shutter release button half pressed. Once you let go the button, it should drop even further. Doing it the other way around (from dark to bright), you will initially see some shortening of the exposure time, and when you let go the button, an even further shortening. If this is indeed the case, than you know why.

Let me know if it works this way.

lock

Zardoz
Zardoz Senior Member • Posts: 1,249
Re: Another strange bug with D4, possibly D800!?!?

Roland Schulz wrote:

Hi there,

today I found the following with my D4: Most times I´m using AF-C and so configured the AF-ON button to AF hold using custom function a8.

So I can focus the camera with the shutter pressed to the first step (continous), and if I like to hold focus to recompose I hold the AF-ON button to save the prefocused distance. So far so good, focus is held, but exposure should be independent to this (have AE-L to switch with the middle of the sub dial, f6).

I see that exposure changes while recomposing, but it´s not the right exposure since when I let the AF-ON button off the exposure changes significantly (may change about 5 stops under certain circumstances)! That´s is not the wanted behaviour and it´s also not found in the manual.

Anyone else found this? Maybe also on D800?

Roland.

Negative on D4, D800, D800e, and secret DnX prototype.

OP Roland Schulz Contributing Member • Posts: 546
Nikon Germany verified this and escalate it now...

Yesterday evening I also described the behaviour to Nikon Germany. Few minutes ago I got the respond that they can reconstruct it. They are also wondering why this happens and that this should not happen.

They escalate the problem to a "higher" position and respond later. I hope it will be solved in a coming FW update.

Roland.

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Nikon D3 Sony a6500
OP Roland Schulz Contributing Member • Posts: 546
Re: This is exactly as expected!

lock wrote:

If you do not lock the exposure, the total scene will be measured with a specific attention to the old spot you focussed on when you press the AF-ON to achieve a focus lock. But, if you move the scene (recompose) and the scene becomes darker, the metering will change only to some extent but because the value metered unde the original focus point still influences the calculated aperture and shutter speed. This chance could very well be rather limited. However, once you let go the button, the camera now evaluates the amount of light under the current focus point in the new scene. That area may be way darker (or brighter), hence changing the values even more.

You can test this by changing the scene using your method of holfing the focus and recomposing. Go from a bright scene with a bright object under focus to a dark scene with a dark subject (without refocussing). You will see a lengthening of the shutter speed while recomposing but holding the af-on button and the shutter release button half pressed. Once you let go the button, it should drop even further. Doing it the other way around (from dark to bright), you will initially see some shortening of the exposure time, and when you let go the button, an even further shortening. If this is indeed the case, than you know why.

Let me know if it works this way.

lock

I don´t expect this since "AF lock only" is AF only, not AE. Nikon Germany already responded to me that they also find this strange and escalate it.

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Nikon D3 Sony a6500
lock Veteran Member • Posts: 6,202
Why don't you try it ?

It's two minutes work.
Things get very complicated when you can lock/unlock AF while the metering uses the information under the 'current' focus point.
The focus point is always used in matrixand in spot. In centerweight it always emphases the center where only the circle size differs (except for average) and the focus point is irrelevant.

lock

NilsPetter Forum Member • Posts: 92
Re: It is the same on my D700

I tested it today, no doubt

-- hide signature --

Regards
Nils Petter Rognstad
Member: NPS

michaeladawson Forum Pro • Posts: 11,034
Can confirm with D800, not D4

Roland Schulz wrote:

Sorry Roland, I can't replicate your issue. Set the camera as you specified. I lock focus and then recompose. The indicated exposure changes for the new scene. When I let go of AF-ON the indicated exposure stays the same. I tried light to dark, dark to light, etc. Not sure what's going on with your camera.

-- hide signature --

Mike Dawson

Hi Mike,
that´s strange, I tried several times, everytime the same issue. You use a D4 (found D800 can´t be configured with the AF-ON button, right?)?? Do you use FW1.04??

As you described you use the right method. This leeds me to the error.

Roland.

I can reproduce your problem with the D800 but not the D4.  My D4 has the latest firmware that was released last week.  1.04?  I tried this morning moving from indoor light to outdoor light through a window.  With AF lock held the indicated exposure changes as I swing the camera from indoor to outdoor light.  When I let go of the lock button the indicated exposure stays steady and it is the correct exposure.

On the D800 I can't set the AF-ON button, but I can assign the AE/AF lock button to be AF Lock Only.  So I did that and repeated the test.  Indoors I focused on something.  Indicated exposure was f/4 at 1/15s. I pressed and held the assigned AF Lock button and swung the camera outdoors.  The exposure changed to f/4 at 1/60s.  But this is way overexposed if I trip the shutter now.  If I release the AF lock button (holding the AF point steady over the same target the exposure jumps to something like f/4 at 1/400s.  This is the correct exposure.

-- hide signature --

Mike Dawson

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Panasonic Lumix DMC-LX3 Nikon D200 Nikon D4 Nikon D800 Nikon D800E +23 more
lock Veteran Member • Posts: 6,202
are metering modes the same on d4 and d800?

Could it be d4 is on center weight and d800 on matrix or spot?

jeminijoseph Veteran Member • Posts: 6,310
try this

Hi there,

today I found the following with my D4: Most times I´m using AF-C and so configured the AF-ON button to AF hold using custom function a8.

So I can focus the camera with the shutter pressed to the first step (continous), and if I like to hold focus to recompose I hold the AF-ON button to save the prefocused distance. So far so good, focus is held, but exposure should be independent to this (have AE-L to switch with the middle of the sub dial, f6).

I see that exposure changes while recomposing, but it´s not the right exposure since when I let the AF-ON button off the exposure changes significantly (may change about 5 stops under certain circumstances)! That´s is not the wanted behaviour and it´s also not found in the manual.

Anyone else found this? Maybe also on D800?

Roland.

After focusing release af-on button and hold the shutter release button. That will keep your exposure. This means both your thumb and fore finger is always working.

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Nikon D500
OP Roland Schulz Contributing Member • Posts: 546
Re: Can confirm with D800, not D4

I can reproduce your problem with the D800 but not the D4. My D4 has the latest firmware that was released last week. 1.04? I tried this morning moving from indoor light to outdoor light through a window. With AF lock held the indicated exposure changes as I swing the camera from indoor to outdoor light. When I let go of the lock button the indicated exposure stays steady and it is the correct exposure.

On the D800 I can't set the AF-ON button, but I can assign the AE/AF lock button to be AF Lock Only. So I did that and repeated the test. Indoors I focused on something. Indicated exposure was f/4 at 1/15s. I pressed and held the assigned AF Lock button and swung the camera outdoors. The exposure changed to f/4 at 1/60s. But this is way overexposed if I trip the shutter now. If I release the AF lock button (holding the AF point steady over the same target the exposure jumps to something like f/4 at 1/400s. This is the correct exposure.

-- hide signature --

Mike Dawson

Interesting: Your D800 behaviour is exactly what my D4 shows, why doesn´t your D4 show the same?! Nikon Germany can also verify the problem. 
I wonder why your D4 works??? Be happy it does, but for me the described workaround is fine so far.

Thanks,
Roland.

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Nikon D3 Sony a6500
OP Roland Schulz Contributing Member • Posts: 546
Re: are metering modes the same on d4 and d800?

lock wrote:

Could it be d4 is on center weight and d800 on matrix or spot?

Mine is on matrix, but doesn´t matter at all: "AF lock only" should be AF lock ONLY!

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Nikon D3 Sony a6500
OP Roland Schulz Contributing Member • Posts: 546
Re: try this

After focusing release af-on button and hold the shutter release button. That will keep your exposure. This means both your thumb and fore finger is always working.

That´s totally different from what I want. I want to keep focus, NOT exposure.

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Nikon D3 Sony a6500
OP Roland Schulz Contributing Member • Posts: 546
Yes, D3 also had that "bug" ;-)!

NilsPetter wrote:

I tested it today, no doubt

-- hide signature --

Regards
Nils Petter Rognstad
Member: NPS

Verified it with my D3, same "wrong" behaviour!! Function is a9 here. Never found that before...

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Nikon D3 Sony a6500
lock Veteran Member • Posts: 6,202
It works if you set a8 to the first option.

And let af to work only with the af on button , a4 first option.

lock

lock Veteran Member • Posts: 6,202
you do not understand what i am saying.

I did not say the af on button locks the exposure. I said that if you lock the af, the camera uses that specific 

area under the focus point to calculate the exposure. It does so despite changes in light in the area outside the focus point. It will continue to take into account the influence of the area you locked your focus on, until you release the af on button. After you release the af on buton, it than recalculates the exposure with the area behind the preferred focus point even if you did not actually acquire a new focus lock.

OP Roland Schulz Contributing Member • Posts: 546
Re: It works if you set a8 to the first option.

lock wrote:

And let af to work only with the af on button , a4 first option.

lock

Lock, you never give up :-), this again is a complete different handling I don´t like (personal taste). My workaround described does it until Nikon corrects this on possibly every of their cameras ;-).

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Nikon D3 Sony a6500
OP Roland Schulz Contributing Member • Posts: 546
Re: you do not understand what i am saying.

lock wrote:

I did not say the af on button locks the exposure. I said that if you lock the af, the camera uses that specific

area under the focus point to calculate the exposure. It does so despite changes in light in the area outside the focus point. It will continue to take into account the influence of the area you locked your focus on, until you release the af on button. After you release the af on buton, it than recalculates the exposure with the area behind the preferred focus point even if you did not actually acquire a new focus lock.

I understand what you write but that doesn´t matter because the camera MUST NOT do that.

The function is "AF lock ONLY"!!! There are four options that handle with AE, I DON´T WANT THEM!!! Nothing in the manual is about exposure with the last option.

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Nikon D3 Sony a6500
lock Veteran Member • Posts: 6,202
That's ok.
If you do not like it, fine. But i tested the same opti

ons as yours  on my d600 (reprogramming the ael/aef button) and it works as i described above, but only with matrix (as you are using). The metering uses the light levels under the focus point you locked, until you release the af on button. Then it uses the area that exists under the chosen focus point in the new scene to reestimate the exposure.

If you do not believe me, just set your camera to center weight or spot and do the same. You will see a different behaviour.
lock Veteran Member • Posts: 6,202
Primarily, it is caused by matrix metering, not Af on.

Matrix emphasises the area under the focus point. If you fix the focus point , the camera will also fix the influence of the light behind the locked focus point. Even if you recompose. It is designed that way, even on my d600.

lock

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