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Canon 50 megapixel sensor

nicolas claris

OPF Co-founder/Administrator
It would fair that the author (Amy-Mae Elliott) does tell where she got that information so we could no if it is a rumor or a well established fact. One could dream!
 

Klaus Esser

pro member
It would fair that the author (Amy-Mae Elliott) does tell where she got that information so we could no if it is a rumor or a well established fact. One could dream!

honestly: i can´t imagine, why they would make a 19x28mm sensor with 50MPx . . . that would be ridiculous. The resulting quality everyone could imagine . . . : terrible.
That´s like making a compact-digi with 16MPx for about 300.-$ . . .

If they would make a 50MPx sensor, it should be MF-size at least 39x48mm. Below that size 50MPx would mean just one thing: noise.

Remenber: actual high-res chips in digibacks need to be cooled to dampen noise. Think about a 1,6-crop-35mm-like camera with such a chip . . . maybe some ice-cubes or a fan attached . . . . :)

best, Klaus
 
"Cooling fan for efficient heat removal"

Do remember that CCDs require more power (which generates heat) than CMOS devices do. Another difference is that CCDs are read by the "bucket-brigade" method, thus accumulating noise at each step, while CMOS can be read per sensel.

The amazing thing is that apparently only Canon has mastered CMOS for quality imaging sensors in both Consumer and Professional image sensor devices.

Bart
 

Klaus Esser

pro member
"The amazing thing is that apparently only Canon has mastered CMOS for quality imaging sensors in both Consumer and Professional image sensor devices."

which professional image sensor devices do you mean? Compared to the digibacks it´s not very prfessional.
Canon´s CMOS are good. No question. But they can compete with none of the backs in terms of dynamics, resolution and noise.
There are good reasons, why photographers spend so much money even for a 17MPx - back.
You´d be surprised by the difference between a 1DsMkII and a P25 for instance . . ask Leonardo!
At least i was surprised using a P25 the first time in comparison to a 1DsMkII!

best, Klaus
 
"The amazing thing is that apparently only Canon has mastered CMOS for quality imaging sensors in both Consumer and Professional image sensor devices."

which professional image sensor devices do you mean? Compared to the digibacks it´s not very prfessional.
Canon´s CMOS are good. No question. But they can compete with none of the backs in terms of dynamics, resolution and noise.

Apples and oranges, please let's compare comparable things. The differences you mention are more related to sensel size (which has its obvious limits in a smaller format sensor array) than CCD/CMOS technology.

Besides, it would be interesting to compare the noise characteristics per sensel (or ultimately per output pixel) scaled for sensel surface area. The dynamic range is largely determined by both the surface area of the sensel, and the 16-bit ADC circuits used (and the 1Ds Mark II successor is rumoured to have just that).

Resolution of the 1Ds Mark II is higher on chip, but because the number of pixels is more limited than from larger sensor arrays the needed magnification works in its disadvantage, so again size related, not technology.

Bart
 

Klaus Esser

pro member
"size related, not technology."

well, you can´t devide one from the other, can you. I understand what you mean, of course. But i doubt a general superiorness (?) of CMOS.
No maker of HighEnd-Backs use CMOS as far as i know. All CCD.

bigger sensels=greater dynamics. Right. Therefore i asked "which professional image sensor devices do you mean?"

Regarding the above reading and compared to others, they don´t have a really "professional image sensor device" yet . . ;-)

Besides: the 1DsMK II is a great device - no question!

bst, Klaus
 
Apples and oranges, please let's compare comparable things. The differences you mention are more related to sensel size (which has its obvious limits in a smaller format sensor array) than CCD/CMOS technology.

Besides, it would be interesting to compare the noise characteristics per sensel (or ultimately per output pixel) scaled for sensel surface area. The dynamic range is largely determined by both the surface area of the sensel, and the 16-bit ADC circuits used (and the 1Ds Mark II successor is rumoured to have just that).

Resolution of the 1Ds Mark II is higher on chip, but because the number of pixels is more limited than from larger sensor arrays the needed magnification works in its disadvantage, so again size related, not technology.

Bart
One can imagine uses for sensors with ultra high sampling. If you can make a sensor that has sufffcient sampling to outresolve the lens, it is possible (IMO) to eliiminate the AA filter without penalty. Assuming the packing fraction of the sensels can be close to one, there is little penalty in term of the total number of detected photons. The designer is then free to use postporocessing as desired. For example, one could resample at a lower sampling frequency, recovering signal-to-noise ratio, at the expense of resolution without introducing Moire or alaising artifacts.
 
One can imagine uses for sensors with ultra high sampling. If you can make a sensor that has sufffcient sampling to outresolve the lens, it is possible (IMO) to eliiminate the AA filter without penalty.

Yes, however... Good lenses (for general imaging) have a limiting resolution of 150 cycles/mm or better (tiny dedicated lenses are much better). That would need an R+G+B sampling density of approx. 3 micron or smaller. In case of a Bayer CFA that would mean something like a 1.5 micron sensel pitch. At a sensel pitch of 1.5 micron, the sensels will have approx. an effective surface of 1x1=1 square micron. If we assume a storage capacity of 1500 electrons per square micron, the photon shot noise is approx. sqrt(1500)=39 with maximum exposure. A signal to noise ratio of 39:1 (at best) will look quite poor (6-7 accurate shades per byte). Such small sensels will also suffer from diffraction at any aperture narrower than f/1.4 .

Assuming the packing fraction of the sensels can be close to one, there is little penalty in term of the total number of detected photons. The designer is then free to use post-porocessing as desired. For example, one could resample at a lower sampling frequency, recovering signal-to-noise ratio, at the expense of resolution without introducing Moire or alaising artifacts.

A 24x36mm sensor array with 1.5 micron pitch sensels will be approx. 16000x24000= 384 Megapixels. You'd need a lot of storage and a lot of processing power to process each image. Also, such small sensels are not very sensitive and will need a very low ISO to keep sensor noise limited.

That seems to be quite a penalty just to replace the AA-filter, if you ask me. And it'll require massive averaging to get anything resembling a decent dynamic range, and will result in a number of output pixels that we already achieve routinely today.

No, to me the most plausible solution is still many large (say 9x9 micron) sensels and 16-bit ADC processing.

Bart
 
"A 24x36mm sensor array with 1.5 micron pitch sensels will be approx. 16000x24000= 384 Megapixels. You'd need a lot of storage and a lot of processing power to process each image. Also, such small sensels are not very sensitive and will need a very low ISO to keep sensor noise limited.

That seems to be quite a penalty just to replace the AA-filter, if you ask me. And it'll require massive averaging to get anything resembling a decent dynamic range, and will result in a number of output pixels that we already achieve routinely today.

No, to me the most plausible solution is still many large (say 9x9 micron) sensels and 16-bit ADC processing.

Bart"

Thanks for your comments but it seems to me that you have taken my suggestion to the extreme. It is not necessary to go to 1.5 microns to achieve adequate sampling from real lenses on a 24x36 mm detector. Processing a 50-100 Mpixel array should be within the state-of-the-art. And rather than reducing dynamic range this approach would substantially increase it. On the other hand, too few large pixels will limit image quality, due to aliasing. The charm of my suggestion is that one can contrive a sensor design that is matched to the available lenses and does not depend on imperfect AA filters.
 
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