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Sony a7RII FW 2.0 raw dark-field histograms, ISO 3200 and up

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A few days ago I posted dark-field histograms from uncompressed files made with version 2 firmware running on the Sony a7II. Yesterday, I posted compressed and uncompressed read noise and engineering dynamic range plots for the a7RII running version 2 firmware.

Today’s post is of dark-field histograms from the a7RII, both compressed and uncompressed. The low-ISO ones are unsurprising and were posted earlier. Now I’m posted the higher-ISO ones.

ISO 1600 uncompressed. 14 bits present. A couple of dropouts.
ISO 3200 uncompressed. 14 bits present. A couple of dropouts.
ISO 1600 compressed. 13 bits present. A couple of dropouts.
ISO 3200 compressed. 13 bits present. One dropout.
ISO 6400 uncompressed. 15 bits present. A couple of dropouts.
ISO 6400 uncompressed. 14 bits present. A couple of dropouts.
ISO 10000 uncompressed. 14 bits present. A couple of dropouts.
ISO 10000 uncompressed. 14 bits present. A couple more dropouts.
ISO 12800 uncompressed. 14 bits present. A couple of dropouts.
ISO 12800 uncompressed. 14 bits present. Lots of dropouts. Digital gain?
ISO 12800 compressed. Dropouts and combing.
ISO 12800 compressed. Dropouts and combing.
ISO 16000 uncompressed. Lots of dropouts.
ISO 16000 uncompressed. Lots of dropouts and combing.
ISO 16000 compressed. Lots of dropouts.
ISO 16000 compressed. Lots of dropouts. Some combing.
ISO 20000 uncompressed. Lots of dropouts.
ISO 20000 uncompressed. Lots of dropouts. No combing.
ISO 16000 uncompressed. Lots of dropouts.ISO 16000 compressed. Lots of dropouts.
ISO 20000 uncompressed. Lots of dropouts. A bit of combing.
ISO 25600 uncompressed. Lots of dropouts.
ISO 25600 uncompressed. Lots of dropouts.
ISO 25600 compressed. Lots of dropouts.
ISO 25600 compressed. Lots of dropouts. Lots of combing.

Now we get to the ISOs where Sony does digital noise reduction.

ISO 32000 uncompressed. Most of the dropouts are filled in.
ISO 32000 uncompressed. Most of the dropouts are filled in.
ISO 32000 uncompressed. Again, most of the dropouts from 13 bits are filled in.
ISO 32000 uncompressed. Again, most of the dropouts from 13 bits are filled in.
ISO 40000 uncompressed. Most of the dropouts are filled in.
ISO 40000 uncompressed. Most of the dropouts are filled in.
ISO 40000 uncompressed. Again, most of the dropouts from 13 bits are filled in.
ISO 40000 compressed. Again, most of the dropouts from 13 bits are filled in.
ISO 51200 uncompressed. Most of the dropouts are filled in.
ISO 51200 uncompressed. Most of the dropouts are filled in, but there are a lot more than at ISO 40000.
ISO 51200 compressed. Again, most of the dropouts from 13 bits are filled in.
ISO 51200 compressed. Again, most of the dropouts from 13 bits are filled in.

Unless there is interest in the nosebleed ISO, I think I’ll stop here.

The departures from ideality, while interesting, will have no effect on normal photography, since there is plenty of read noise dither.

 

Comments

  1. Uncompressed: there appears to be one level missing every 26, which would suggest digital scaling post ADC by about (1+1/26). Below ISO10000 it’s probably just compensating for slightly lower analog gain. Above ISO 10000 there is some other digital scaling before x (1+1/26) is applied. This additional factor seems to get back in sync at ISO40000. With a bit of thinking one could figure out what it is.

    The interesting implication of this digital scaling is that the Black Level should shift with ISO. Does it? 🙂

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Unless otherwise noted, all images copyright Jim Kasson.