Accurately comparing FF vs APS-C sensor performance? An open discussion.

Started Apr 8, 2013 | Discussions thread
Wally626 Senior Member • Posts: 2,312
Re: Accurately comparing FF vs APS-C sensor performance? An open discussion.

Rab G wrote:

You mention DXOmark what about camera iso settings compared with actual measured level have you looked at the A99 graph for that it looks bad really bad!!!

The A77 iso setting against measured setting seems to be much more accurate than the A99 so would that not make it difficult to compare shots supposed to be at the same iso ?

For example  snr 18% results

A99 measured  iso 439 manufacturers iso 800

A77 measured  iso 635 manufacturers iso 800

A99 measured iso 913 manufacturers  iso 1600

A77 measured iso 1302 manufacturers iso 1600

A99 measured iso 3762 manufacturers iso 6400

A77 measured iso 5412 manufacturers iso 6400

A99 is WELL out on all iso measurements.

The average difference for the A77 from your numbers is 0.29 stops and the A99 0.81 stops. This 1/2 stop difference is about the same amount the DXO ISO ratings for the A99 are below what would be expected for the sensor.

Has anyone verified this is real life conditions with the A99. For instance use an incident meter to calculate an exposure for a scene and use those numbers to take the image. I would really be suprised if in real life the A99 was missing the exposure by .8 stops.

I did a quick and dirty check with my A77 and it was off about 0.3 stops which would be inline with your numbers above.

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