Tuesday, September 18, 2012

CMOSIS Sensor in "Leica M" Rangefinder

CMOSIS announced that it has developed a 24MP HDR full-frame sensor exclusively for Leica Camera AG geared to an important volume market. The new "Leica M" digital camera launched at Photokina 2012 incorporates the full-custom CMOSIS "Leica MAX 24MP CMOS Sensor" with active area of 36 x 24 sq.mm, aka the full-frame 35mm format. The sensor is the first milestone in a long term, strategic cooperation between Leica Camera AG and CMOSIS.

"This is the first time that a CMOS image sensor for a 35mm high-end camera was designed, and is manufactured, in Europe for a European customer," said Guy Meynants, CTO at CMOSIS, Antwerp, Belgium. "Apart form the ceramic IC package the Leica MAX 24MP CMOS Sensor is a 100-percent European product."

The new sensor features 6um pixels and is made by STMicroelectronics in Grenoble, France, using 300mm wafers in their IMG175 CIS technology. STM's 110nm frontend and 90nm backend CIS technology with copper metallization was originally developed for CMOS image sensors with 1,75um pixels for mobile phones and other consumer applications. The large die size, larger than the reticle size, requires the use of one-dimensional stitching.

The 6um pixel has a linear full well capacity of ≥40,000e- and a linear DR close to 76dB. Pixel data are digitized by patented low-power, high-speed 14-bit column ADCs. The sensor features an electronic rolling shutter with global reset and noise cancellation through both analog as well as digital correlated double sampling (CDS) resulting in low temporal and spatial noise and non-uniformities.

Special care was taken in the sensor development to reduce crosstalk between neighboring pixels for a wide range of incident light angles. The sensor reduces spatial crosstalk by its very thin stack from color filters to photodiodes. Microlenses with a strong curvature and high top height focus the incoming light rays in the center of each pixel's photodiode. The resulting low angular sensitivity of the QE at high ray angles was achieved by the particular features of STM's 110/90nm CMOS process. This allows the "Leica M" to accept the full range of high-quality lenses in the camera system, which includes wide-angle, large aperture lenses, at their full optical performance.

The full resolution frame rate is 5fps. The 24MP sensor also allows Leica to offer, for the full HD video recording and a live preview on an M-model camera. Power consumption of the sensor chip at full speed and resolution is specified at 700 mW.

It is housed in a 78-pin ceramic package covered by a customized glass with anti-reflective coating and near-infrared cut-off filter.


Update: EETimes Europe published an explanation picture on large angle of incidence in CMOSIS pixels:


Update #2: Electronic Specifier published a complete set of facts about the CMOSIS-Leica sensor.

15 comments:

  1. I understand that this chip is intended to replace the existing M9 CCD sensor for leica's flagship camera the new M. The intention is to retain the advantages of CCD and combine this with the advantages of a CMOS sensor. It will be interesting to see how close they have come to achieving their goal.

    From Leica Press Release:
    ..."This new development successfully transfers the characteristic advantages of CCD sensors, such as natural and brilliant color rendition and impressive reproduction of details, to a CMOS sensor."...

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  2. Congratulations to Leica, CMOSIS and ST Microelectronics. For Leica this is a new design from a new design house in a new technology from a new foundry. A major achievement ! I planned to visit Photokina tomorrow and will for sure take a look at the camera.

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  3. yet another manufacturer utilizing column ADC ... where does that leave Canon?

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  4. About 7e read noise if I did the math right.

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    1. Correct for the base ISO gain setting.
      Read noise reduces with higher analog gain (used for the higher camera ISO settings).

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    2. what is the dark current level please??

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  5. This comment has been removed by the author.

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  6. How many stops of dynamic range will this sensor render? Anyone know?

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    1. If the dynamic range reading on the CMOSIS specs are true, then this would equate to about 12.5 stops :)

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  7. why is the dynamic range so low?

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  8. Compare this to other similar sensors: Canon EOS 5D mark III, also full frame with 6 micron pixel, has a dynamic range of 11.65 stops at iso 200 according to DXO mark. See tabblad "measurements, dynamic range" on http://www.dxomark.com/index.php/Cameras/Camera-Sensor-Database/Canon/EOS-5D-Mark-III

    Of course that is after the camera processing, but I don't think that 12.5 stops is "so low".

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    1. These days Canon sensors are behind in dynamic range and so is apparently this new CMOSIS sensor. The Sony-manufactured 36 Mpixel sensor in the Nikon D800 achieves 14.4 stops of dynamic range, while the 24 Mpixel sensor in the Nikon D600 achieves 14.2 stops of dynamic range according to DxOMark.

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    2. Be careful: DXO resamples to 8 Mpixel when you take the 'print' option (at left upper corner of their evaluation charts) and then indeed shows 14.2 stops for D600.

      You have to compare using the 'screen' option in the DxO charts. Then Nikon D600 is measured to be 13.44 stops at iso 100 and 12.9 at ISO 200 (actual ISO is 159 according to DxO). The Leica camera has a minimum iso of 200, so the 12.5 stops is not too bad.

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    3. DxO do not have access to totally unprocessed raw data. For them the camera is a black box. Only Nikon knows if there is any processing applied the raw-files.

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  9. I don't get this dynamic range (DR) hysteria. Get the exposure correct and you will be fine with DR around 10-12 stops. Statistically the human eye has a DR of 6-7 stops. Eye eye movement and the iris adapting under few seconds gives DR 20 stops.

    I wonder why all the HDR pictures looks unnatural to me. That is not how I perceive the scene in my mental image.

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