"Real ISO" again and DXO charts (not again!)

Started May 1, 2012 | Discussions thread
OP Peter 13 Veteran Member • Posts: 8,301
Re: They do report at the manufacturer's ISO

rhlpetrus wrote:

Peter 13 wrote:

Horshack wrote:

The data points on DxoMark SNR graphs are at the nominal ISO values (manufacturer's ISO).

The SNR they measure at ISO 1600 for the 5D3, for example, is reported as SNR at 1280. My question is: why?

Have you read their way of measuring ISO? It's not same as most manufacturers use to calibrate their exposure systems (saturation x midtone gray, respectively).

Yes. The first [definition] (what they use) relates sensitivity to the exposure necessary to saturate the camera.

Why would you care what saturates the sensor in low light, when you are ss limited?

Thus the differences. It's not that their 1280 ISO is same as the camera's 1280 ISO.

I know that. The question is what does this tell you about the low light performance.

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