why only 51200 ISO while 1DX has 204800? i can't believe their sensosr has 2 steps difference in sensivity.
Why not. ISO limits are set by firmware. Photosamples are jpeg's, which implies Dual Digic magic fairy dust... As long as the RAW noise levels are on par, we should be ecstatic!
Then I wasn't that wrong with my guess.
So, given this fact there are some additional technical questions:
Can a sensor get hacked then to yield more ISO range?
Let's say if Canon implements a derivate of the 1Dx sensor into the new whatever 5D (as posted at NL today) and lock it to 51200?
The other question:
Are sensors "programmed" to a certain ISO range or are they kind of "neutral"?
Thanks for helping a non-tech.[/list]
Pedro let me try :
A) Don't know about sensors being hacked; but certainly the system can be "hacked" for example, I have an older Rebel XT with a nominal max ISO setting of 1600. There are hacks out there that let you set it at 3200. These hacks do not compensate for added noise nor do they increase the NR or Sensor performance, but allow you to shoot at 3200 (which results in more noise), but is possible.
B) Yes; they can lock allowable ISO settings at any lower level they want. There could be an upper limit to which the analog amplifiers will saturate, but I suspect the image will be very useless before the chip op-amps saturate i.e. the image is overrun with distortion + Noise. Manufacturers do this to differentiate products routinely.
B2) Sensors have the ability to collect light / photons. They collect Chroma based on the Bayer sensor, they are as neutral as the Bayer filter allows. On the other hand, since light is collected over time, the system can use a smaller "time slot" (high ISO) and lock the signal, amplify it based on the small sample of data it has collected. The higher the ISO, the smaller the sample of data collected that can be reconstructed as an image. Digital noise and artifacts are by-products of this reconstruction.
If you look at the sensor Die, there is a lot of surface area taken up by electronics not just photo diodes (light collectors) . The extra electronics reduces the efficiency of collection of light. Since the ratio of surfaces of the photodiodes to "extra electronics" goes up with sensor size, so does it's ability to collect more light cleanly. Hence larger sensors have lesser noise.
Sony has just patented such a sensor design, it purports a 20% increased surface area for the actual photo diodes. Seems very promising, but yet to be tested in real life.
Hope this helps.