Exposure Diagnostic help please

[AB26]

Have a look at the mode dial on top of a D40 "P" and "Auto" are both there are you telling me they are the same?

"P" means Programmed Auto
"S" means Shutter Priority Auto Mode
"A" means Aperture Priority Auto Mode
and "M" means Manual mode - the only mode that does not have an "Auto" function.

And on a DSLR "Auto" means P&S.

[pnodrog]

We actually agree on "P,S,A,M" and my D800 and from memory the D200 do not even have a setting called "auto" but the D40 and some other entry level DSLR's do. The D40 mode dial has two groups of settings. The above ones we agree on and another group with Auto being the first followed by about 5 little symbols such as a face,mountain,flower etc. None of this group react to EC.

Once again have a look at the mode dial on a D40.

[Stagecoach]

Andre,

On my D300 there is no way of adjusting exposure value from the 'Menu' function. So can not do similar test plus its very dark here at present.

So, from what you are saying if Exposure Compensation of say +3.0EV has been entered from the 'Menu' function in the D40 and then you enter -3.0EV using the thumbwheel and +/- button the exposure will be 0.0EV BUT the Exif will show the +3.0EV that is set in the 'Menu'. I would have thought that any EC entered with the thumbwheel (the manual refers to the two methods of entering it) is also going to directly adjust what has been be set in the Menu method.

I did manage on my camera this morning in 'Programmed' mode with -4.0 EV dialed in to point it around to get a sunny 16 exposure reading registered, lock it, and take a picture of a 50/50% sky and land shot that was exposed reasonably well.

Grahame

[Stagecoach]

Paul,

The D40 has scene modes including one called Auto of which the manual refers to as a point and shoot mode. It then also has P, S, A, & M of which the P is referenced to in the manual as 'Programmed Auto'.

EC only works with P, S & A modes.

Grahame

[AB26]

EC only works with P, S & A modes.

And "M"

The rest are all P&S modes, like my wife has on her Fuji P&S.

[Stagecoach]

Paul, Andre

What I can now also confirm looking through all Catalinas pics Exif in ViewNX is that modes used have been, 'Programmed Auto'
'Manual' and 'Auto'.

It is the 'Programmed Auto' ones that it is now certainly the 'P' mode that are the ones with the mega ECs. Shots taken in 'Auto' mode (p&s) show no EC as expected.

Grahame

[Stagecoach]

And "M"

The rest are all P&S modes, like my wife has on her Fuji P&S.

My error it only indicates for P,S, A according to the manual but works.

[AB26]

Andre,

On my D300 there is no way of adjusting exposure value from the 'Menu' function. So can not do similar test plus its very dark here at present.
Grahame

I think it is in the setup menu, not sure. I will come back to you on that one.
The D200 and D40 are very similar, therefore I have the idea there might be a setting that needs to be changed on Catalina's camera.

With regard to the Exif: No I think the EC value dialled in will be recorded, the menu EC is for correcting exposure on a sort of "permanent" basis. I will come back to you on this one as well.

[pnodrog]

I think we all agree(and have for sometime) on the modes available. I think Colin was referring to "Auto" mode not "P" when he said no EC was applied.

A possible explanation for Grahame

The basic "Auto" is very likely to follow the same speed/aperture selection curve a "P" but not apply any EC.
EXIF info may report them as the same but add a reference to the curve used N2?
EXIF info may also report the EC value set even if it was not applied.

It would be interesting to test a D40 and see what actually happens.

[AB26]

EXIF info may also report the EC value set even if it was not applied.

I think that is what we are trying to find out. Can it actually happened? Can a computer lie?
Is the exif accurate? Does not seem to be, hence Grahame's question.

How can you give the right advice if the exif is not accurate? An EC of -4.7 seems to be crazy, or does it?
Can you capture a reasonably exposed image with EC set at -4.7?

A challenge to find out.

[Colin Southern]

Can you capture a reasonably exposed image with EC set at -4.7?

I would expect it to have significant noise issues, at best, on a camera like that.

Why doesn't someone with the same camera try it?

But it still doesn't add up; EC-4.7 wouldn't have given those aperture / shutter-speed / ISO figures in what was in essence a "sunny 16 rule" situation; the shutterspeed would have been around 1/8000th @ F16, not 1/500th @ F11.

[inkista]

Except, Colin--is that really a "sunny 16" scene? It looks lower than sunny 16 conditions to me (cloud cover vs. direct sunlight) by at least a stop, possibly two (don't they say for heavy cloud cover you need three more stops from sunny-16?), which might make the EC value seem slightly less gargantuanly off.

Does anybody know what the Gain Control field being set to 1 ("low gain up") means? [maybe there was in-camera exposure boosting in JPEG conversion?] And that this shot was SOOC, vs. processed via HDR or using a grad ND or something?

[Stagecoach]

JUDGES SUMMING UP AND VERDICT

Well this has sure been an interesting one but what a pity we don't have someone with a D40 handy.

I have come to the following assumption based on thread input, web research and hopefully common sense

a) The mode in question that was showing the very high EC as having been used was the 'P' (programmed auto) mode of which EC can be used.

b) There is no way that Nikon would have designed a camera for which the function of EC having a value entered by one method, the menu, would be added or subtracted to when a value is entered using the other input option of the -/+ button and thumbwheel. Simply, the single EC value has two methods of lowering or raising that value (as does the ISO on my D300).

c) Exif data shows the settings (A,S, ISO) the image was taken at when the shutter operated. The EC value shown in the Exif simply indicates the value that the user offset what the camera 'thought' was the best setting based upon what it's meter registered for the scene.

d) There is nothing to suggest in any of the images a fault with the EC indications, they have been varying and also show as 0.0 in modes where we know EC is not available.

d) The image posted can be produced as follows and all evidence suggests it was;

The camera in 'P' (Programmed Auto) mode with a -4.7EV value entered (possibly inadvertently) if aimed at a bright part of the sky can give a reading around sunny 16 figures, 1/500th f11 and if the shutter is pressed half way down at this point those readings/settings are locked.

If the camera is then moved to frame the scene as posted, shutter button fully pressed, the resulting exposure will be reasonable. A good image will be produced but with strange Exif regarding EC.

I had planned to do an example this morning but unfortunately the view from my house through the rain is similar to a grey card.

Grahame

[Colin Southern]

Except, Colin--is that really a "sunny 16" scene?

My guess would be yes - pretty close; light cover giving directional diffused light, so not much attenuation.

Keeping in mind too that the over-exposed portion is shooting into the light.

Keep in mind too that you can never get an occasion where you'll get a standard exposure by attenuating sunny 16 settings by 4.7 stops - you'd need +EC on a darker day, not -EC.

[jcuknz]

Should av bought a Canon!!!

WRONG ..... No a Panasonic

[AB26]

I would expect it to have significant noise issues, at best, on a camera like that.

Colin a camera like that might surprise us.

A 6MP APS-C CCD sensor with a massive pixel pitch. It seems the D40 renders very good low light images with very little noise. At ISO 400 the tests of DP Review show very little noise.

Agreed: The “recorded” ISO, Aperture and Shutter speed look like the correct settings for the exposure that was attained. The EC of -4.7 is a mystery and simply does not add up.

[AB26]

I have come to the following assumption based on thread input, web research and hopefully common sense

Grahame,

The setting in the menu, I was talking about, is actually the “Exposure Fine Tune” settings. It can be adjusted in increments of ⅙ to a maximum of 1.0 stop. Dump that idea I had, it does not apply.

After doing some tests with my D200, I did found some interesting results.
I dialled in an EC value of -4.7 using the ± EC button. In the viewfinder the -4.7 is indicated and the exposure meter indicates that the image will be way under exposed. At -4.7 I could not find a way of compensating by making adjustments using the main Command Dial only. Back to the drawing board.

Next:
Step 1) Setup: Tripod, ISO 400, “P” mode, RAW, EC(using ± button)=0. Result = Perfect Exposure.

Step 2) Setup: As above but using ± button to dial in EC of -2.0. In the viewfinder the exposure meter indicates an image that will be under exposed. Correct for under exposure by using Command Dial only. No adjusting, using ± button. Result = Perfect Exposure. Review EC set by using ± button, still at -2.0.

Step 3) Exactly as in step 2, except, EC of -3.0 dialled in using ± button. Result = Perfect Exposure. Review E.C. setting in top screen, EC value = -3.0.

Step 4) Download and check Metadata. Result = All three images has exactly the same Shutter Speed, Aperture and ISO. Despite the EC value indication on the top panel the Metadata recorded, was the settings used as the image was captured (the correct data for the exposure attained). The E.C. value indicated on the top panel does not appear in the Metadata.

Conclusion: Though the EC value was changed, using the ± button, the Metadata recorded were the settings, countering EC by using the Command Dial only. This makes me ask the question if it is possible that the firmware version in the D40 might be recording different settings in the Metadata. You might dial in EC value by using the ± button and then counter the setting by using the Command Dial only but the firmware version records the value dialed in by using the ± button and not the value as countered by the Command Dial.

Well, for me it is back to the drawing board, again. There has to be a logical explanation to the question at hand. I have to find the answer.

Assumption is the mother of all – you know what.

Thanks Grahame, a very interesting “problem” to research.

[AB26]

d) The image posted can be produced as follows and all evidence suggests it was;

The camera in 'P' (Programmed Auto) mode with a -4.7EV value entered (possibly inadvertently) if aimed at a bright part of the sky can give a reading around sunny 16 figures, 1/500th f11 and if the shutter is pressed half way down at this point those readings/settings are locked.

If the camera is then moved to frame the scene as posted, shutter button fully pressed, the resulting exposure will be reasonable. A good image will be produced but with strange Exif regarding EC.

I had planned to do an example this morning but unfortunately the view from my house through the rain is similar to a grey card.

Grahame

Would that not produce an under exposed sky and the rest will be black? (In "P" mode you will be under exposing the sky by 4.7 stops.)

[Stagecoach]

Andre,

Grahame,

The setting in the menu, I was talking about, is actually the “Exposure Fine Tune” settings. It can be adjusted in increments of ⅙ to a maximum of 1.0 stop. Dump that idea I had, it does not apply.

I have not come across the “Exposure Fine Tune” function or indication within the D40 manual.

After doing some tests with my D200, I did found some interesting results.
I dialled in an EC value of -4.7 using the ± EC button. In the viewfinder the -4.7 is indicated and the exposure meter indicates that the image will be way under exposed. At -4.7 I could not find a way of compensating by making adjustments using the main Command Dial only. Back to the drawing board.

I agree with this in that based upon the D40 manual in 'P' mode (Programmed Auto) when dialling in EC using the +/- button and command dial the info will appear in the viewfinder showing both the EC figure plus the meter which will be biased to either the + or - side depending upon EC amount entered.

But, you will not be able to compensate (correct) for this under/over exposure because by rotating the command dial when in 'P' mode you are using the 'flexible' function of it which alters the balance between Speed/Aperture but the exposure always remains the same. The EC function simply gives you a lighter or darker image from what the camera brain had assumed was the best.[/QUOTE]

Next:
Step 1) Setup: Tripod, ISO 400, “P” mode, RAW, EC(using ± button)=0. Result = Perfect Exposure.

Step 2) Setup: As above but using ± button to dial in EC of -2.0. In the viewfinder the exposure meter indicates an image that will be under exposed. Correct for under exposure by using Command Dial only. No adjusting, using ± button. Result = Perfect Exposure. Review EC set by using ± button, still at -2.0.

Step 3) Exactly as in step 2, except, EC of -3.0 dialled in using ± button. Result = Perfect Exposure. Review E.C. setting in top screen, EC value = -3.0.

I can not understand how you have achieved these results as according to the D40 manual and undertaking the same tests on my D300 they can not be achieved.

In 'P' mode you can not alter the resulting exposure by using the command dial only, you can only alter balance between Speed/Aperture. I undertook tests, P mode 0.0EV perfect exposure, dialled in -2EV (using +/- button plus command dial) took image well under exposed, adjusted command dial only that upped Aperture and downed Speed took picture and way underexposed exactly as the previous.

I can only assume that the D200 mode of operation in P mode is different to that of the D40 and D300, or, you undertook these tests in 'S, A or M' mode.[/UNQUOTE]

Step 4) Download and check Metadata. Result = All three images has exactly the same Shutter Speed, Aperture and ISO. Despite the EC value indication on the top panel the Metadata recorded, was the settings used as the image was captured (the correct data for the exposure attained). The E.C. value indicated on the top panel does not appear in the Metadata.

Conclusion: Though the EC value was changed, using the ± button, the Metadata recorded were the settings, countering EC by using the Command Dial only. This makes me ask the question if it is possible that the firmware version in the D40 might be recording different settings in the Metadata. You might dial in EC value by using the ± button and then counter the setting by using the Command Dial only but the firmware version records the value dialed in by using the ± button and not the value as countered by the Command Dial.

Still can not see any way that you can counter any EC value that has been entered by just rotating the command dial (thumbwheel)[/QUOTE]

Well, for me it is back to the drawing board, again. There has to be a logical explanation to the question at hand. I have to find the answer.

Assumption is the mother of all – you know what.

Thanks Grahame, a very interesting “problem” to research.

It's certainly been puzzling me and of course there is still the unknown actual affect of being able to dial in EC from either the +/- button and command dial or through the Menu system.

I did suggest to Catalina that the best thing to do a while ago was a two button reset as this will 0.0 any EC values entered. Going through the images again Catalina has also used 'Manual' for a couple of which EC values show. With the D40 which only has one Command dial when in Manual mode you use the +/- button plus the Command dial to adjust Aperture and this same method adjusts EC when you are in 'P' mode, could cause confusion/error.

Grahame

[Stagecoach]

Would that not produce an under exposed sky and the rest will be black? (In "P" mode you will be under exposing the sky by 4.7 stops.)

Andre,

Correct, I mixed up my pluses and minuses but the procedure is the same. Here's an example, one image taken at 0.0EV and the other taken with a -4.7EV dialed in, aimed at a darker area, exposure locked, re-composed and hey presto an image with very confusing metadata.

'P' mode, 1/500. f11, ISO400, 0.0EV (result as would be expected)


'P' mode, 1/500, f11. ISO400, -4.7EV set and indicated.


The very slight difference in exposure is due to changing light conditions due to the clouds or framing being slightly different.

I also managed it no problem indoors at these settings so it does demonstrate that this is something that can happen either inadvertently or deliberately. It possibly also ties in with comments from Catalina that she has been moving the camera around all over the place to get focus as AF is not working?

Grahame