Hi,
My understanding is that there is little difference between CMOS and CCD regarding image quality, it is just different circuit design. The main differences are:
- CMOS has additional electronics in each pixel, making the sensel smaller (advantage CCD). This also means that a CMOS sensor without microlenses has worse fill factor than CCD.
- CMOS can be read out nondestructively, allowing for "correlated double sampling" (advantage CMOS)
- CMOS can have much lower read out noise, D800 advantage in DR comes from this (advantage CMOS)
- CMOS now has useful live view
Color is only affected by the CGA (Color Grid Array) and not by circuit technology.
Most of the advantage Nikon has in DxO mark probably comes from the low readout noise, that really helps dynamic range but also high ISO.
Canon seems to have some issues with their CMOS sensors, readout noise is quite high and they seem to have worse noise characteristic than Nkon. It seems that Nikon simply cuts away some noise, while Canon is less aggressive, making Canon better for some astronomic work.
The Nikon D800 sensor is developed and made by Sony. Most of the advantage is coming from Sony's design with an ADC (Analog Digital Converter) for each column of the sensor.
In my view and experience DR may be a bit overrated. I never had problems with lack of DR on any of my cameras. Also, all the advantage in DR is in the shadows. Highlight DR is same on all cameras, except if they under expose intentionally. Fujifilm has some technologies to extend highlight DR, by having extra pixels assigned for highlight.
My guess is that MF digital has advantages in three areas:
- A larger sensor can collect more photons, always an advantage. Shot noise is reduced. Helps with DR but not that much (around one stop).
- The lenses are less stressed for MTF. MTF for an ideal lens drops almost linearly with pixel size, so larger pixels mean better MTF
- The CGA may have better characteristics, especially if it is designed without much concern for high ISO
Best regards
Erik
Forgive my ignorance here.... but how can this new Nikon CMOS sensor out perform a medium format CCD sensor like that in the IQ180 which is supposed to have "better ?" pixels?? I'm really curious, being the owner of the Phase P65+, which it also beat in the new DXO tests... I'm wondering if the D800 and D800e will have creamy smooth files at base iso like medium format sensors too.....thanks, Eleanor