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Phase One Trichromatic, the future of Sony A7r III/A9r?
  
 
dgpfotografia
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p.1 #1 · p.1 #1 · Phase One Trichromatic, the future of Sony A7r III/A9r?


Hi,

Phase One just launched their new 100MPx digital back. They call it Trichromatic. By the name I thought something foveon-like, but at the end it is an special Bayer Matrix: https://www.phaseone.com/trichromatic

Anyway, what cought my eye it is a new ISO 32 setting in the back. That will really make an interesting option for a future A9r or A7r III, cleaner shadows and better DR...

Regards,

David



Sep 13, 2017 at 12:29 PM
jhinkey
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p.1 #2 · p.1 #2 · Phase One Trichromatic, the future of Sony A7r III/A9r?


Not sure about the cleaner shadows and better DR part. From SAR:
"This is Bayer with better color filtration. The red channel is only red with little green mixed in, ditto for the green, blue channels.
Anyone with experience with color filter in the good old days of black and white film photography knows that you can make the color filter be “purer” and does a better job of rejecting unwanted colors, but this will result in greater light loss. Applied to digital sensors this means you can always sacrifice high-ISO performance in return for better color fidelity. For the clientèle of a medium format system like this, this trade-off makes perfect sense."

If you are reducing your total light gathering efficiency there are penalties to be paid.



Sep 13, 2017 at 01:52 PM
Paul Gardner
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p.1 #3 · p.1 #3 · Phase One Trichromatic, the future of Sony A7r III/A9r?


Looks good to me. Better color for me beats high ISO any time. Highest I ever shoot is 800. 1 to 2 FPS is fast enough, more accurate focus at the expense of speed. Put Playmemories focus bracketing on a function key, or better yet make it auto ala PhaseOne. Personally I dislike bokeh. Give us a true landscape camera.


Sep 13, 2017 at 03:19 PM
snapsy
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p.1 #4 · p.1 #4 · Phase One Trichromatic, the future of Sony A7r III/A9r?


Here's an article from DxO which explains how the color filters affect color purity and noise:

https://www.dxomark.com/Reviews/Canon-500D-T1i-vs.-Nikon-D5000/Color-blindness-sensor-quality



Sep 13, 2017 at 03:36 PM
dgpfotografia
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p.1 #5 · p.1 #5 · Phase One Trichromatic, the future of Sony A7r III/A9r?


jhinkey wrote:
Not sure about the cleaner shadows and better DR part. From SAR:
"This is Bayer with better color filtration. The red channel is only red with little green mixed in, ditto for the green, blue channels.
Anyone with experience with color filter in the good old days of black and white film photography knows that you can make the color filter be “purer” and does a better job of rejecting unwanted colors, but this will result in greater light loss. Applied to digital sensors this means you can always sacrifice high-ISO performance in return for better color fidelity. For the clientèle
...Show more

I was thinking more in the ISO 32. Not sure if Sony can borrow the Bayer layout... for some Phase ONE press information, looks like that it is exclusive to Phase ONE.



Sep 13, 2017 at 03:39 PM
Matt Grum
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p.1 #6 · p.1 #6 · Phase One Trichromatic, the future of Sony A7r III/A9r?


dgpfotografia wrote:
That will really make an interesting option for a future A9r or A7r III, cleaner shadows and better DR...


Sadly not.

This is an example of why it is good to separate ISO values from noise values in your mind. ISO is not a measure of noise (at least not the way most camera manufacturers measure it) but instead is a measure of how quickly the sensor saturates. If you take a camera with base ISO 50, and glue an ND filter over the sensor you get a camera with base ISO 25. But DR and shadow noise will be exactly the same (for the same reason that putting an ND filter on the lens and increasing exposure time to compensate has no effect on DR/noise).

If you take a sensor with base ISO 50 and double the well depth, then base ISO will drop to 25 (ISO is a measure of how quickly the sensor saturates) and you will gain a stop in DR. This is the situation with the D810.

So it is important to understand that low base ISO is not automatically a good thing, it can mean your sensor has deep wells, or it can mean your sensor has shallow wells which fill up slowly because it is very inefficient and throws light away.

The new PhaseOne is an example of the latter - the sensor becomes less efficient and thus base ISO lowers, but you gain nothing in terms of noise or DR.


Edited on Sep 14, 2017 at 12:47 PM · View previous versions



Sep 13, 2017 at 03:49 PM
ytwong
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p.1 #7 · p.1 #7 · Phase One Trichromatic, the future of Sony A7r III/A9r?


"This is Bayer with better color filtration. The red channel is only red with little green mixed in, ditto for the green, blue channels.
That sounds like the original Bayer filter to me (). If so, Trichromatic seems a fancy name for old stuffs.
Manufacturers went for different color filters to let more light in, thus improving noise performance.

Quite a few years ago, people said a major different of sensors between Sony A900 and D3X is the color filter. Some claims A900 has better color at the cost of worst noise performance. ( I don't owned either of them, and that was just what I read)

Maybe sensor noise is so good nowadays that they can afford to bring back the real RGB filter to get better color and sacrifice noise performance a bit?




Sep 13, 2017 at 03:54 PM
Matt Grum
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p.1 #8 · p.1 #8 · Phase One Trichromatic, the future of Sony A7r III/A9r?


dgpfotografia wrote:
Not sure if Sony can borrow the Bayer layout... for some Phase ONE press information, looks like that it is exclusive to Phase ONE.


This is not a new concept, in fact the trend has been slowly in the opposite direction, weaker filters which sacrifice colour sensitivity in order to get better low light results.

But for a studio camera it makes sense. Note this isn't a new Bayer arrangement, it's just a CFA with narrower frequency response, so the green pixels are less sensitive to red and blue light etc.

There's no reason Sony couldn't use similar (though not identical) filters. Or go for a tetrachromatic sensor if you really want to throw low light ability under the bus!

You could also reduce the fill factor of the microlenses for increased resolution if you don't care about low light performance.




Sep 13, 2017 at 04:04 PM
ZhanMing12
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p.1 #9 · p.1 #9 · Phase One Trichromatic, the future of Sony A7r III/A9r?


This does make me wonder if there's a market for a pure studio camera with base ISO of 5 (i.e. ~4 stops from ISO 100). That'll mean ~17 stops of DR at base ISO with the D850/A7r II sensor, but your ISO 400 shots look like ISO 6400...

...I'd be interested in one.



Sep 13, 2017 at 04:11 PM
 

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Matt Grum
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p.1 #10 · p.1 #10 · Phase One Trichromatic, the future of Sony A7r III/A9r?


ZhanMing12 wrote:
a pure studio camera with base ISO of 5 (i.e. ~4 stops from ISO 100). That'll mean ~17 stops of DR at base ISO with the D850/A7r II sensor, but your ISO 400 shots look like ISO 6400...


No it wouldn't. For the same reason putting a 4 stop ND filter on the lens doesn't give you 17 stops DR.

The only way you'd get that increase is if the full well capacity was 16 times higher!

http://www.fredmiranda.com/forum/topic/1508485/0#14179986




Sep 13, 2017 at 04:20 PM
ytwong
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p.1 #11 · p.1 #11 · Phase One Trichromatic, the future of Sony A7r III/A9r?


I also wounder how that CFA would affect details for objects in Red or Blue color. For example, a red silk dress would have little to no blue and green color, so only 1/4 of the pixels get signals while to other 3 (1 blue, 2 green) get almost nothing.


Sep 13, 2017 at 04:21 PM
mttran
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p.1 #12 · p.1 #12 · Phase One Trichromatic, the future of Sony A7r III/A9r?


Good enough for me if A7Riii/A9R beats the read noise performance of low iso A7R and hi iso A7R2.


Sep 13, 2017 at 04:29 PM
dgpfotografia
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p.1 #13 · p.1 #13 · Phase One Trichromatic, the future of Sony A7r III/A9r?


Matt Grum wrote:
If you take a sensor with base ISO 50 and double the well depth, then base ISO will drop to 25 (ISO is a measure of how quickly the sensor saturates) and you will gain a stop in DR. This is the situation with the D810.

So it is important to understand that low base ISO is not automatically a good thing, it can mean your sensor has deep wells, or it can mean your sensor has shallow wells which fill up slowly because it is very inefficient and throws light away.

The new PhaseOne is an example of the former
...Show more

Thanks for the explanation, I was always assuming the case of the d810 is what happens, where you get double capacity wells.

I didn't look at the specs of the new sensor from Phase ONE, where did you see that it contains shallow wells? (I see some videos about the new sensor in DPReview, but I have not seen then yet).



Sep 13, 2017 at 06:47 PM
zhangyue
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p.1 #14 · p.1 #14 · Phase One Trichromatic, the future of Sony A7r III/A9r?


ISO is analog gain, is it? Lower ISO doesn't make full well take more photon, but always reduce read noise from analog design point of view. (High gain low noise design is a challenge always)

That is why Nikon D810 had better DR than the same Sony sensor with ISO 64.

If this sensor come from Sony and it is done right I expect it will have better DR at base ISO.



Sep 14, 2017 at 04:54 AM
zhangyue
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p.1 #15 · p.1 #15 · Phase One Trichromatic, the future of Sony A7r III/A9r?


I wouldn't expect next Sony will have meaningful better DR than now as it already reaching a certain level approaching max for current technology. We didn't see any improvement over last five years since.D800/A7R at pixel level. The only chance is further increase pixel count so you get better DR at print (down sampling)

However, with speed up of DSP in future, I can certainly predict it can maximize its stacked sensor tech to do average images in digital domain to maximize DR. Say 1/60s, you can average 4 images, that will give you 6dB DR right there.

mttran wrote:
Good enough for me if A7Riii/A9R beats the read noise performance of low iso A7R and hi iso A7R2.




Sep 14, 2017 at 05:07 AM
Matt Grum
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p.1 #16 · p.1 #16 · Phase One Trichromatic, the future of Sony A7r III/A9r?


dgpfotografia wrote:
I didn't look at the specs of the new sensor from Phase ONE, where did you see that it contains shallow wells?


Shallow compared to if they had achieved ISO 32 by making them deeper. The actual full well capacity will in all likelihood be exactly the same as the previous version, all that has changed is that less light is reaching each pixel.

---------------------------------------------

zhangyue wrote:
ISO is analog gain, is it?


No, it's a measure of how quickly a sensor becomes saturated.

zhangyue wrote:
Lower ISO doesn't make full well take more photon


There are two ways to reduce the ISO value (for a given amplifier setting), increase the well depth or reduce the number of photons that are converted (make the sensor/microlenses less efficient). Both of these mean the sensor takes longer to saturate.

zhangyue wrote:
If this sensor come from Sony and it is done right I expect it will have better DR at base ISO.


It's the same "sensor" it just has a different colour filter array, which lets less light through hence the base ISO value is lower, but this doesn't mean better DR.



Sep 14, 2017 at 12:17 PM
joelRichards
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p.1 #17 · p.1 #17 · Phase One Trichromatic, the future of Sony A7r III/A9r?


I wonder if this tech was also used in Sony's new Venice CineAlta camera which has a lower than expected base ISO but supposedly unmatched color. Kinda makes me wonder if they didn't just tweak the A9 sensor and add this new color filter...


Sep 14, 2017 at 05:24 PM
zhangyue
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p.1 #18 · p.1 #18 · Phase One Trichromatic, the future of Sony A7r III/A9r?


Matt Grum wrote:
Shallow compared to if they had achieved ISO 32 by making them deeper. The actual full well capacity will in all likelihood be exactly the same as the previous version, all that has changed is that less light is reaching each pixel.

---------------------------------------------

No, it's a measure of how quickly a sensor becomes saturated.

There are two ways to reduce the ISO value (for a given amplifier setting), increase the well depth or reduce the number of photons that are converted (make the sensor/microlenses less efficient). Both of these mean the sensor takes longer to saturate.

It's the same "sensor" it just has
...Show more

Your definition of ISO apply to base ISO fine (I am not even sure for base ISO, there is no signal amplified after photon conversion in digital camera) but in digital camera system. ISO really means signal (voltage here)amplified by analog amplifier before convert to digital. For a camera with base ISO 100, ISO 25600 really means a gain of 256 applied before convert to digital. I am not sure this ISO number has to bond with sensor saturation. The only reason I bring this concept up is because we are talking about DR but not definition of ISO itself. And Amplifier design will affect read noise.

I spend some time try to find information how Nikon use A7R sensor to make ISO64. It seems there is no well explained info how they did it. BUt from DR level comparison between the two, it looks like it just be able to make the well can hold more photon to gain extra DR. This is also the reason it compete well with any miniMF in DR given 1.7X area in miniMF.

As for phase CFA, I really really doubt CFA can reduce light by a factor of 4 in this case using Sony sensor. I also doubt manufacture can simply use ND effect to claim low native ISO camera, (though I am not knowledge enough to know for sure) given Nikon was able to get ISO64(not by ND) from Sony sensor I am inclined to believe Phase can squeeze more DR with Sony sensor by having ISO32.



Sep 15, 2017 at 04:45 AM







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