a7S high ISO claim - - -over hyped or not ?

Started Jul 3, 2014 | Discussions thread
andrewD2 Veteran Member • Posts: 9,037
Re: a7S high ISO claim - - -over hyped or not ?

Rishi Sanyal wrote:

andrewD2 wrote:

ProfHankD wrote:

andrewD2 wrote:

The A7R is reading better in THEIR DR tests because of the resolution.

Read the full set of tests at DxO. Rather than viewing "scores," click on "measurements" and then "dynamic range." Two plots are available there. The "print" one shows the dynamic range at each ISO when all images are first scaled to 8MP (the default graph). The "screen" one shows the dynamic range at the native pixel resolution -- not giving the A7R (or A7) an advantage, but essentially penalizing them for their higher resolution.

At no time can the A7s resolve 36MP. That means if the detail is resolved in a moderate to high DR scene by the A7r DESPITE a little more noise per pixel at ISO100 it will still be an apparent winner. On an extreme DR scene who knows. 10 stop push back? Anyone tried that?


I'm not sure what you're trying to say, but if one camera has more base ISO DR than the other for one scene, it'll also have higher base ISO DR for any scene, no matter what the DR of that scene.

Apologies in advance if I'm misunderstanding what you're trying to say.


A dynamic range measurement has to have a cut off at which you say 'this isn't good enough quality shadow detail to be counted as useful DR'. In other words you can say, this camera has 13stop DR of a high quality, or it could be measured as 15 stops DR if the quality threshold is lower.
DXO marks DR results are hopeless, a 5DIII still registers some info at a similar DR to a 6D but the banding of the 5DIII makes the last few stops of DR of very poor quality. Some of the Sony sensors show good detail but the limitation is colour accuracy.

On a 15 stop scene it maybe they (A7R and A7S) both pull up acceptably noisy detail from the deepest shadows and the higher megapixels resolves more detail. However if you pulled up detail from a more extreme scene (or even the same scene shot underexposed) it maybe (I'd have to test it) the lower megapixel camera is still showing some detail whereas the higher megapixel camera gives you nothing useful.


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