Dpreview: “A7rII has posterization artifacts in certain conditions”.

August 24, 2015
reviews
184 Comments

Note: The A7rII waiting list is getting shorter. If you order the A7rII now at Amazon (Click here) you will have to wait 2-5 weeks to get it.

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Dpreview just posted an article about the ISO behaviour of the A7rII. While the state that the A7rII has a very high dynamic range they also complain about the lossy Raw files showing some posterization artifacts in certain conditions:

With the a7R II, Sony continues the tradition of lossy Raw files, with no option for lossless 14-bit Raw. This isn’t going to affect all your photographs, but it can rear its unsightly head at high contrast boundaries of pushed files. The area around the sign in the ISO 100 + 6EV and ISO 200 + 5EV shots have artifacts not present in the higher ISO shots. These posterization artifacts are due to Sony’s lossy compression, which you can read more about in Iliah Borg’s excellent study here.
We think this Raw compression is particularly a shame, especially when you consider how ISO-invariant this camera is otherwise. As you saw above, the pushed ISO 200 shot has very little additional noise compared to the ISO 6400 shot. This is because of the high dynamic range, and ISO-invariance, of the camera, which means that realistically you can save much of your image brightening for post-processing as opposed to increasing your ISO setting in-camera. However, you’ll be limited in your ability to do so because of Raw compression, essentially meaning the camera isn’t as ISO-invariant as it could be.

I am 100% sure Sony will release a firmware update to allow current A7 owners to shoot real 14 bit RAW. The pressure on Sony is too high to not bring this feature.

One more interesting note: DearSusans actually claims the Sony RAW files on the A7rII are “tweaked”. They shoot stars with the A7r and A7rII and noticed a clear improvement on the A7rIi files:

Doing so with files from the A7r produces square artifacts around stars, as seen above. The same intermediate processing on A7rII files did nothing of the kind. Now, this is not to say lossy compression is ideal or perfect. And, if it adds significantly to the already improved image quality, we’re all for lossless RAW compression, here at DS. But something already has changed and, apparently, in the right direction.

Give us 14 bit Sony, we on SAR want to get the best out of our great Sony sensors! P.S.: My personal request…add 64 ISO too :)

A7rII preorder list:
In USA: at Amazon, BHphoto, Adorama, SonyStore US, FocusCamera, Uniquephoto.
In Europe at Sony DE, UK, FR, IT, ES, NL, BE, CH, AT, SE, FI, NO, PT. Wex UK.
In Asia at Digitalrev, CameraPro.

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