Update: Sept 17
Note: This is brand new and may not work on all cameras. It works on 5D3 from my testing. Please let me know if you have tested this modules with other cameras to update this post
If you know nothing about ETTR then go here:
(Auto) ETTR (Exposure to the Right): -- History & Beginners Guide
http://www.magiclantern.fm/forum/index.php?topic=5693.0If you know nothing about DUAL ISO then go here:
Dual ISO - massive dynamic range improvement
http://www.magiclantern.fm/forum/index.php?topic=7139.0For a comparison of ETTR and DUAL ISO go here:
Dual ISO vs Auto ETTR
http://www.magiclantern.fm/forum/index.php?topic=7835.0What is new?The Auto Exposure To The Right module has now been expanded to squeeze the last bit of information of the camera sensor by the automatic use of DUAL ISO. This is best used in situations where the high dynamic range of the scene require DUAL ISO to better capture the details of the image. The latest implementation analyzes the image and automatically decides when to use DUAL ISO.
For the latest ETTR and DUAL ISO Modules go here:
Nightly Builds - try the very latest stuff here
http://www.magiclantern.fm/forum/index.php?topic=3072.0PLEASE BE ADVISED THAT THESE MODULES ONLY WORK IF YOU HAVE ENABLED THE BOOTFLAG IN YOUR CAMERA.If you want to enable the bootflag in your camera (550D, 600D, 50D, 60D, 5D2) then go here:
Magic Lantern v2.3 - Install Guide
http://wiki.magiclantern.fm/installFor other cameras go here for a starting point.
RAW video & ML -- Beginners Guide, FAQ & Useful Links -- READ FIRST
http://www.magiclantern.fm/forum/index.php?topic=5520.0HOW TO USE IT!1. The modules are located in the EXPO tab: Auto ETTR and Dual ISO

2. Auto ETTR has a simple mode:

Click on the Advanced mode to display all of the settings.
3. ... and an Advanced mode:

4.
Trigger mode allows you to select three different methods for triggering the use of the AETTR.
Press SET means that every time press the SET button the current scene is displayed in the LCD monitor with an analysis of the image.
HalfS DblClick means that every time double press the Half Shutter the current scene is displayed in the LCD monitor with an analysis of the image.
Always on means that every time you take a picture the image is displayed in the LCD monitor with an analysis of the image.
Auto Snap means that every time you take a picture the image is displayed in the LCD monitor with an analysis of the image, and that if the results are not adequate it will automatically take another image.
5.
Slowest shutter: Set the slowest shutter that will allow for the current scene.
6.
Exposure Target: A general exposure target for the scene, cannot be set to zero but it could be set lower to expose darker. This is not really used very much, usually left at -0.5
7.
Highlight ignore: Percentage of (highlight) pixels to ignore when calculating ETTR. This is used if you want to allow overexposure in the highlights, for example room lights. Typical setting is 0.2% and means ignore almost nothing. If you want to ignore more highlights try 1, 3, 5 or even 10%.
8.
Allow Clipping: No clipping This selection allows to select Clip Green channerl, and Clip ANY channel. Only used if you want to allow clipping of higlights for any channel or only Green Channel specifically. Some people will allow for some green channel clipping since there is more detail information on the other channels. This would allow for the maximum exposure to the right and yet maintaining the highlight details.
9.
Midtone SNR limit: Is defined in EV levels of noise in the Midtones form 1 to 8 EV. The higher the SNR the less noise. Typical settings from 4 to 8 EV.
10.
Shadow SNR limit: Is defined in EV levels of noise form 1 to 4 EV. The higher the SNR the less noise. Typical settings from 2 to 4 EV.
11.
Link to Canon shutter: This links the Slowest shutter to the shutter value you set via small scroll wheel. This is very useful for quickly changing the Slowest shutter without having to go into the ML menu. Just set the shutter speed and on the next photo Slowest shutter = new shutter.
12.
Link to DUAL ISO: ON or OFF. In ON position the camera will analyze the scene via Trigger mode (4) and decide if DUAL ISO is required or not. Requires the DUAL ISO module to be enabled.
Note: If Link to DUAL ISO is set to OFF, the module will not calculate the required DUAL ISO and the image will only be set to meet the ETTR requirements.
13.
Show debug info: ON OFF. Will show some of the important calculation results of this module.
Convergence to results: a. This module with require at least two images (sometimes three or four) to come up with the proper exposure. Alternatively you can set the Trigger mode to Set in which case the camera will go to live view, analyze the scene, and return to photo mode with the correct settings.
b. When the algorithm cannot find an adequate exposure it will beep twice and give you a message in the LCD screen. ETTR: expo limits reached, indicating the ISO and speed limits used.
c. When the algorithm finds an adequate exposure it will beep once and give you a message in the LCD screen. ETTR settled at ISO xxx and the shutter speed.
Note: the image review time in the LCD is set via Canon menu in Image Review. You may want to put 8 seconds so you can see the results in the LCD before it turns off.
Raw histogram use:It is best to enable RAW Histograms via Global draw. This will put a little histogram on the LCD during image review. This histogram can show an ETTR hint (how many EVs are required to reach ETTR), or the Dyanmic Range of the image. It will also show the clipped channels via colored numbered circles.
If you also enabled RAW zebras via Global draw, you will also see, if any, areas of the image are over-exposed. Black will be completely overexposed, then you can see red, green, and blue channels clipped areas shown with their respective colors. White will be dark areas completely under-exposed.
More about SNR Levels:Here you can find some samples at different SNR levels:
http://www.magiclantern.fm/forum/index.php?topic=5200.msg70150#msg70150Some test I did here:
http://www.magiclantern.fm/forum/index.php?topic=7835.0