Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Guillermo Luijk on June 25, 2020, 06:23:25 pm

Title: Crazy effective ISO measurements on the 1DX III on DxOMark
Post by: Guillermo Luijk on June 25, 2020, 06:23:25 pm

This is what DxOMark is showing about their effective ISO measurements:

(http://guillermoluijk.com/misc/canon1dxiiiiso.png)

That behaviour (a high effective ISO, assumed to correspond to an equally higher than normal ISO gain), was typical on old sensors to maximize captured DR at risk of clipping some highlights.

But when we look at equally exposed RAW files on the 1DX III and 1DX II, they are nearly identical (same highlight headroom and SNR performance):

(http://guillermoluijk.com/misc/canon1d.jpg)

Something seems to have gone wrong with DxOMark testing on the 1DX III.

Regards

Title: Re: Crazy effective ISO measurements on the 1DX III on DxOMark
Post by: Simon J.A. Simpson on June 26, 2020, 02:29:09 am

It would be interesting to know how DxOMark measure and calculate their effective ISO sensitivity.

Title: Re: Crazy effective ISO measurements on the 1DX III on DxOMark
Post by: digitaldog on June 26, 2020, 10:26:12 am

Indeed, doesn't  pass the smell test.

Title: Re: Crazy effective ISO measurements on the 1DX III on DxOMark
Post by: Guillermo Luijk on July 09, 2020, 04:16:30 pm

The summer trainee at DxOMark seems to have been replaced by a more expertised one:

BEFORE
(http://guillermoluijk.com/misc/canon1dxiiiiso.png)

NOW
(http://guillermoluijk.com/misc/canon1dxiiiisocorrect.png)


Regards