Connecting Exposure, ISO and Noise

[Leping]

Great.  This is exactly what DxO found (0.7Ev DR decrease from ISO 800 to 1600, 1Ev from 1600 to 3200, etc.)  I do understand that DxO Labs use 1:1 (0dB) SNR for the DR definition that differs from yours, but in the top right portion of your chart the curves are quite parallel to each other...

[attachment=11925:DR_Curves.jpg]
Someone have to go ahead and test a Nikon...  Not the D3/D700 but the D3x, for which the DR keeps increasing by around 0.8Ev/ISO stop all the way to ISO 100, if the measurements are accurate.  As someone mentioned Nikon and Canon use vastly different methods for readouts and as seen from many many examples (Lloyd, etc.) the D3x's read noise is way lower than the Canons and even their own D3.  I have the raw data from DxO lab to share with the interested.

Both the 5DII and the D3's DR curve bend flat at ISOs below 800, while the D3x's keep raising almost linearly.

And, with little doubt, the D3x's red channel is a lot cleaner than the Canons.

The result: ETTR for the Canons, ETTC or even ETTL if you have important highlights on a D3x.

Yes or no, depending on the actual camera and ISO.

Emil's advice above is very good, as generous consideration. I find it generally usefult to explain something from different angle of view for a better understanding. I use now the Canon 5DMkII for the explanation.

Down below are the noise graphs at the different *real* ISOs, i.e. ignoring those, which are only numerical derivatives, as they are never useful for the raw data. The horizontal lines represent a given level of noise; the intersection with the graph of an ISO value shows, how great the dynamic range can be with that level of noise. The difference in EV between two ISO settings at a given level of noise shows, how much you gain (or lose) when selecting this or that ISO.
......

[Panopeeper]

Someone have to go ahead and test a Nikon...  Not the D3/D700 but the D3x

Well, someone should make the test shots, like Erik Kaeffehr did with the A900 and Marc McCalmont with the 5D2.

I have the raw data from DxO lab to share with the interested

Upload a sample please, I take a look at if and how far I can use it. For example Imaging Resources files are not useful for *this* purpuse. Their color checker and gray step cards are downright dirty, and the exposure is too high. I can't use nice, well exposed shots, I need by three stops underexposed ones.

Btw, if you have tham, one from the A900 would be very interesting; not for measurement (Erik's shots are excellent), but perhaps I can show, why DxO misevaluated the DR and noise.

with little doubt, the D3x's red channel is a lot cleaner than the Canons

I don't have a monochromator (nor the camera) to make a full spectral response analysis, but I did compare the filter transmissivity on white, on the primaries and on a few other patches of the color checker card (on IR's images, with reliably constant illumination).

I don't see a *huge* difference (I see a larger difference in the blue). However, one needs to add the difference of the ISO sensitivity (the D3X "utilizes" the exposure better than the 5D2), then the difference is relevant.

[Leping]

Hi Panopeeper,

Thanks for replying.  I only have Excel spreadsheet from DxO Lab with the measurement numbers.  Did you play and test a D3x first handed?

Please show us how DxO "misevaluated the DR and noise", despite that their DR curve and yours are almost exactly the same if one knows how to read these charts properly.

Thanks,
Leping

Upload a sample please, I take a look at if and how far I can use it. For example Imaging Resources files are not useful for *this* purpuse. Their color checker and gray step cards are downright dirty, and the exposure is too high. I can't use nice, well exposed shots, I need by three stops underexposed ones.

Btw, if you have tham, one from the A900 would be very interesting; not for measurement (Erik's shots are excellent), but perhaps I can show, why DxO misevaluated the DR and noise.

[Panopeeper]

I only have Excel spreadsheet from DxO Lab with the measurement numbers

I understood your I have the raw data from DxO lab that you have the raw data, i.e. the raw files.

Did you play and test a D3x first handed?

No, and I don't have good raw images for any evaluation.

Please show us how DxO "misevaluated the DR and noise", despite that their DR curve and yours are almost exactly the same if one knows how to read these charts properly

I referred to the A900 specifically. I will post about that within a few days. The documentation of my finding (i.e. proving it) is extremely labour intensive, and it will repulse most readers for being extremely pixel peeping, so I am pondering about what to include at all.

[ErikKaffehr]

Hi,

Would be most kind if someone would shoot the D3X raw images Panopeeper needs for evaluation.

- I used a syntetic Color Checker downloaded from ftp://www.rags-int-inc.com/fromrags/photo...CC_Calc_Lab.psd
- Printed this on semigloss A4 paper, important to avoid fingerprints and dust
- Illuminated by two cheap halogen lamps about 45 degree angle on each side, trying to avoid reflections
- Underexposed 4 steps

I sent the files to Panopeeper using yousendit com. Please note, it has taken some iterations, Mr. Panopeeper is not easy to satisfy ;-)

Best regards
Erik

I understood your I have the raw data from DxO lab that you have the raw data, i.e. the raw files.


No, and I don't have good raw images for any evaluation.


I referred to the A900 specifically. I will post about that within a few days. The documentation of my finding (i.e. proving it) is extremely labour intensive, and it will repulse most readers for being extremely pixel peeping, so I am pondering about what to include at all.