D4 vs 1Dx (Imaging Resource), RAW, ACR, 6400-12800

Started Sep 4, 2012 | Discussions thread
Andre Affleck Senior Member • Posts: 2,362
Re: D4 vs 1Dx (Imaging Resource), RAW, ACR, 6400-12800

Lance B wrote:

However, the other elephant in the room is that, added to the fact that each camera's ISO may be inaccurate (which is what I had pointed out originally), apertures and shutter speeds may also be inaccurate, so setting the shutter and aperture to be the same in both the cameras being compared in order to then test the noise level of the appropriate ISO may also be fraught with danger as this will also throw out the results.

So, without knowing that every aspect of each camera is accurate in the exposure area, then we are still just specualting when it comes to the noise levels at certain ISO's.

Not if the reviewer knows what he is doing. In all fairness, I don't think Image Resource ever intended to provide images for this kind of scutiny, but other reviewers like DXO do.

Simply put, one can actually get a fairly accurate count of the total number of electrons captured (converted photons) by looking at the raw units (ADU) that are recorded within the raw file. By determining the "unity gain" of the camera (through a series of tests) you can easily calculate how many digitized electrons got converted to raw levels. Unity Gain is essentially the true base ISO, where there is no amplification, so every captured photon equates to 1 raw level. I am oversimplifying the explanation since I am not an expert like bobn2, but essentially the actual exposure can still be determined through testing irregardless of the actual aperture size and shutter time.

In any case, like you have alluded to in your response, this is all really academic. Even considering the difference in exposure, the performance of the two cameras are so similar, one will not be able to tell the difference once you processed them IMO. Photographers will use them as they wish, and they will still deliver stunning images regardless.

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