D600 RAW is not much better than A900

Started Sep 27, 2012 | Discussions thread
Allan Olesen
Senior MemberPosts: 2,145
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Re: D600 RAW is not much better than A900
In reply to Michel J, Sep 29, 2012

Michel J wrote:

Allan Olesen wrote:

Modern sensors lose less than half of the photons. So not much more to gain there.

Hum....! If «less than 50%», that suggest a big margin to make some progress...

That is less than 1 stop. In your other thread, you were claiming much larger improvements.

With the current technology, the camera can only know that those photons were infrared if it blocks them for some pixels and allows them for other pixels - just like the bayer filter we have today to make color photos. This blocking results in a loss of photons, so you may not gain a net benefit.

On the other hand, if someone invents a sensor which can count all photons and at the same time discern between their wavelengths without blocking some of them in a bayer filter, we would take a step forward in sensitivity. I don't even know if that is theoretically possible (there are some laws of physics which say that you cannot theoretically measure all properties for some systems precisely at the same time).

Who talk about Bayer, me?

My point was that the most efficient color sensors we have today use Bayer.

It may very well be that other technologies have the potential to be more efficient because the don't need to throw away photons to discern between colors. That was actually covered in my second paragraph.

But as long as these sensors have not yet proven that ability, I will assume that they have the same problem.

Have already patents for new design, without Bayer matrix.

But we have also Foveon and Sony version of the Foveon sensor.

I don't know enough about the Foveon sensor. I assume that it also has the same disadvantage of having to throw photons away to discern between colors, or some other similar disadvantage. Otherwise I would have expected it to prove better than a normal sensor with Bayer filter years ago.

Btw, a new sensor dedicated to lowlights could have a bits count conducive for lowlights
(not for highlights)

From extreme highlights to deepest lowlights, like this:

EV N°1 : 1 bits (extreme highlights)
EV N°2 : 2 bits
EV N°3 : 4 bits
EV N°4 : 8 bits
EV N°5 : 16 bits
EV N°6 : 32 bits
EV N°7 : 64 bits
EV N°8 : 128 bits
EV N°9 : 256 bits
EV N°10 : 512 bits
EV N°11 : 1024 bits
EV N°12 : 2048 bits
EV N°13 : 4096 bits
EV N°14 : 8192 bits (deepest lowlights)

You are essentially asking for a non-linear A/D-conversion. But what do you achieve by having such fine-grained bit values at low light that one additional photon would increase the pixel value with several 1000? One photon is the lowest possible increase in light quantity. Trying to count photons in quantities of 0.001 is just a waste of bits.

(Modern cameras actually try to count fractions of photons already around ISO 1000. No need to make it even worse.).

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