G6 vs newest sensors: Real difference in high ISO noize

Started Mar 5, 2014 | Questions thread
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Re: G6 vs newest sensors: Real difference in high ISO noize
In reply to Øyvin Eikeland, Mar 6, 2014

Øyvin Eikeland wrote:

Anders W wrote:

11848 along the X-axis. What I do not get is this: How can I find the dynamic range (or SNR) you will get if I set the camera to an ISO of 25600?

If you expose up to the clipping point of the RAW file, the DR of the image would be the value indicated in the graph (6.61 EV). If you expose less than that it would be correspondingly less (one EV less DR for each EV less exposure).

The difference between the E-M5 with a camera ISO of 25600 and a measured ISO of 11848 and another camera, X, with a camera ISO of 25600 and a measured ISO of 25600 is that at the same exposure (and the meter of the two cameras would normally suggest the same exposure) the ADU values in the RAWs of camera X would be slightly more than one EV closer to the clipping point than that of the E-M5.

Consequently, when camera X is at the clipping point of the sensor, the E-M5 is slightly more than one EV below the clipping point. When the E-M5 is at the clipping point, camera X is has slightly more than one EV worth of clipping.


I think I understand more now. Let me try to use this in a couple of examples. _IF_ I assume that you do not want or need the extra headroom that the Olympus E-M5 provides. I then take that you can disregard the extra dynamic range above the clipping point of a "vanilla" camera where ISO 12800 actually is measured to ISO 12800.

Assuming you are recording raw files: If you don't want the extra headroom, just ignore the camera's meter, expose to the right (using the excellent live-view overexposure warning to quickly and easily calculate the optimum ETTR exposure settings in real-time) and use the numbers straight from the DxO graphs.

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