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A9 dynamic range: choice or side effect of sensor?
  
 
Jonathan Brady
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p.1 #1 · p.1 #1 · A9 dynamic range: choice or side effect of sensor?


I'm pondering the DR of the Sony α9 and why it's lower at base ISO than the other Sony cameras, and even less than the (lower MP) Canon 1DX Mark II. I'm wondering if it was a conscious choice on Sony's part, or if it is a side effect (limitation) of the new sensor design.

The reason I'm wondering about this is the feasibility of a Sony α9R (or perhaps a Sony α7RIII). If this was a conscious choice on Sony's behalf - a trade-off like Canon and Nikon have done (1DX Mark II and D5) to favor better performance at higher ISO, then it's irrelevant for an α9R or α7RIII. But, if it's a side effect, or limitation, of the stacked sensor design, then unless Sony pulls out some wizardry, those cameras will likely have less DR than the α7RII.

Does this matter? Probably not, for me anyway. There's only about 2/3 of a stop of DR difference between the α7RII and the α9 at base ISO and I'm not the kind of user to exploit that difference.

This is just stuff rolling around in my head. Any thoughts?



Sep 20, 2017 at 01:34 PM
GMPhotography
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p.1 #2 · p.1 #2 · A9 dynamic range: choice or side effect of sensor?


I can barely notice it. Has not been a issue yet. I shot the A7rII and A9 together and it's not apparent.
To me it's far too little difference and also can be made up in post. Do not let that stop you from the A9.



Sep 20, 2017 at 01:43 PM
Jonathan Brady
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p.1 #3 · p.1 #3 · A9 dynamic range: choice or side effect of sensor?


Have no desire for the α9. Well, I take that back... I do if it's tech is NOT implemented in an α9R, α7RIII, or α7III (preference in that order - assuming the 7 series doesn't get the body update of the α9). But I'm banking on either an α9R or an α7RIII with the α9 body.

I still wonder about the source of the DR difference, though :-) lol



Sep 20, 2017 at 01:48 PM
Duckysaysquack
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p.1 #4 · p.1 #4 · A9 dynamic range: choice or side effect of sensor?


I'm just speculating, but I'm guessing it's a side effect of the camera's ultra fast silent readout. 20fps on silent mode is a pretty good achievement. On the A7rii and A7sii, the silent shutter comes at a cost - pretty bad banding issues and degradation of quality compared to traditional shutter. The lighting speed has to come at some cost. From a marketing standpoint, Sony wouldn't release a new camera with less DR than their previous cameras, (we're not talking about Canon here, after all...haha).


Sep 20, 2017 at 02:12 PM
 

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Stoffer
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p.1 #5 · p.1 #5 · A9 dynamic range: choice or side effect of sensor?


Jonathan Brady wrote:
But, if it's a side effect, or limitation, of the stacked sensor design, then unless Sony pulls out some wizardry, those cameras will likely have less DR than the α7RII.


This is what I'm going to assume for the time being. The stacked sensor means a ton of data is being moved around super close to the light collection diodes and this results in increased base/background noise. Maybe Sony can get around this on a stacked sensor that doesn't need the super fest readout of the A9. The is also a first generation stacked sensor for full frame, so there is hope for improvements.

But it is a very interesting question, because the stacked sensor is the future of mirrorless if you want super fast AF and fully electronic shutter with no viewfinder blackout. If it cost is always lower base DR, it would be a two step forwards, one step backwards or a one step forwards, two step backwards depending on your need.

We will know more if the A7r3 or A9r is going to use a stacked sensor, but it might not if top image quality is the main target.



Sep 20, 2017 at 02:27 PM
Holger
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p.1 #6 · p.1 #6 · A9 dynamic range: choice or side effect of sensor?


Jonathan Brady wrote:
I'm pondering the DR of the Sony α9 and why it's lower at base ISO than the other Sony cameras, and even less than the (lower MP) Canon 1DX Mark II. I'm wondering if it was a conscious choice on Sony's part, or if it is a side effect (limitation) of the new sensor design.

The reason I'm wondering about this is the feasibility of a Sony α9R (or perhaps a Sony α7RIII). If this was a conscious choice on Sony's behalf - a trade-off like Canon and Nikon have done (1DX Mark II and D5) to favor better performance
...Show more

With BSI you profit more with smaller pixels. But if I look at Bill Claffs read noise values, the A9 seems to be tuned for higher isos. The gain changes at around iso 640 reversing the performance compared to the A7rii. Another change of slope seems to be at around iso 1600, where now both A7rii and A9 read noise curves have the same slope, with the A9 being lower in magnitude. Interestingly you find the A9 to be slightly better from this iso on when looking at the DR measurements of DXO, too.

A recent report on Sony (Dpreview):
And as we learned during our visit, most of the advancements in the a9 stem from new sensor technologies.
Two to three years ago, how would it have been possible to predict sensor readout speeds that offer autofocus calculations at 60 fps and a fully electronic shutter that is only a stop behind the speed of mechanical shutters?
[...]Yasufumi Machitani, project leader on the a9, talked to us about the development of the camera. A number of its features, like blackout-free shooting and fast AF/AE calculation, require sensor readout speeds conventionally thought impossible. A stacked BSI-CMOS sensor with integral memory was necessary for these technologies, and the camera divisionís awareness of such coming sensor technology years in advance allowed it to plan the a9.

I guess that, together with the differently tuned sensor, the new sensor technology is another factor as suggested by others, too.



Sep 20, 2017 at 02:53 PM
SoundHound
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p.1 #7 · p.1 #7 · A9 dynamic range: choice or side effect of sensor?


Yes, I too believe that the A9 sensor is optimized for Hi ISO so as to compete with the Nikon D5 (fitted with a Sony "foundry made" sensor) and Canon 1Dx MKII. I have the D5 and find in the ISO 6400-12,800 range, that due to the way I use it (*) that the A9 doesn't suffer from Hi ISO comparison to my D5.

* Sony's 24-70 and 70-200 GM lenses have F2.8 "T" stops compared to the equivalent, slower T stopped Nikkor zooms. Also the Sony EVF allows me to cope with exposure changes much faster and accurately which leads to, overall, better exposures. However, the A9's Highest ISO stop short of the D5' 3 million (even less with 20 fps shutter) so the Nikon D5 remains "The Queen of the Night."



Sep 20, 2017 at 03:33 PM
mttran
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p.1 #8 · p.1 #8 · A9 dynamic range: choice or side effect of sensor?


exmor rs is sony stepping stone of speed improvement in sensor development. It will take their milc to different level in noise, DR, frame rate, AE/AF, Video, etc...after couple generation from their current RXseries & A9. I always like their outside of the box processes to advance their product, so it would be sony choice in this case.


Sep 20, 2017 at 04:27 PM







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