DPReview Studio scene comparison up!

Started May 30, 2014 | Discussions thread
Dale Cotton Senior Member • Posts: 1,937
Re: RX100M3 BSI or non-BSI sensor

BSI. The specs on Sony.ca say 1" 20.1 MP Exmor R sensor. The R is Sony code for BSI. A non-BSI Exmor is just Exmor. So far as I know, the base ISO thing could indicate a physical tweak to the sensor or to its supporting electronics or a firmware tweak to the BIOS. What that implies is that Sony is now able to get optimum results at 125 ISO instead of 160 and so can also now offer 80 ISO at below-base, rather than just 100.

However, to quote from the DPReview:

"The actual sensitivity of each indicated ISO is measured using the same shots as are used to measure ISO noise levels, we simply compare the exposure for each shot to the metered light level (using a calibrated Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV (the margin of error given in the ISO specifications). In our tests we found that measured ISOs from the Sony DSC-RX100 II were undersensitive by 1/3 stop, meaning ISO 160 indicated = ISO 125 measured."

And the DxOMark measurements show at least that much variance. So all Sony would have to do is change its ISO factoring to conform with real values, and we'd see exactly this return to base 125. This would also result in a slight worsening of apparent noise at all ISO settings compared to the Mk2. By this theory, perhaps Sony no longer feels the need to make the BSI tech look impressive, or perhaps the availablility of faster apertures means they no longer feel the need to fudge to make the slower max apertures of the Mk2 look like better options than they are. Or more likely, there's something else going on entirely and I'm just having a conspiracy theory attack.

PeterPic wrote:

I'm still confused about the sensor. I noticed the base ISO is also different 125 for the M3 vs 160 for the M2.

This seems similar to the discussion around the RX10: http://www.dpreview.com/forums/thread/3622276#forum-post-53094803

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RX100 Base ISO = 125

RX100II, with BSI sensor, Base ISO = 160

RX10, with BSI sensor (allegedly same sensor as RX100II), Base ISO = 125


So, I see two options:

1) The sensor is the non-BSI one from the M1. This would explain the results, but the marketing / specs are wrong. Seems a silly mistake

2) The sensor is some new BSI version, this makes the marketing correct, but the imaging a step back. This seems silly as well.

Can anyone crack open the camera?

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