Magic Lantern's Dual ISO Feature May Boost Dynamic Range To 14 Stops (Or Fry Your Sensor)
One of the recent Magic Lantern announcements is in my eyes a real bomb on the photo industry. Their Dual ISO feature (announcement here) may increase dynamic range by three stops. (video sample below).
This feature is a bit different from adding zebra lines or removing automatic gain, or even providing RAW video as it changes low-level sensor parameters directly. It also is the first time, AFAIK, that Magic Lantern does imaging R&D rather than simply enabling camera hidden features. The analysis can be found on this PDF.
The method works by exposing some of the sensor's vertical lines in ISO100 and some of them in ISO1600 utilizing the entire 14 stops range available on the sensor.. Currently this only works with the 5Dmk3 and 7D - from the text I understand (though may be wrong) that there are no plans to back-port it.
Here is what a1ex writes in the ML forums:
Time for the first real image quality improvement in ML history
a trick that samples half of the sensor at ISO 100 and the other half at ISO 1600, for example. If you mix these two, you can get almost the entire dynamic range the sensor is capable of (around 14 stops). 5D3/7D only.
There are no motion artifacts; not even a difference in motion blur for the two exposures. So, it works well for fast moving subjects.
This code changes low-level sensor parameters. In the technical doc you can see how this method messes with the feedback loop for optical black, for example. Therefore, it's safe to assume it can fry the sensor or do other nasty things. My 5D3 is still alive after roughly one week of playing with this, but that's not a guarantee.
We don't pay for repairs. Use it at your own risk.
Price to pay
- Half resolution in highlights and shadows
- Aliasing and moire - of course, in highlights and shadows
- You can no longer check critical focus when zooming in
If I were Canon, I would just write a big fat check out to the folks at Magic Lantern.