can you post a detailed description of how to use and process dual iso? ive tried it but the results are not good
Well, you could have a look at the ML site but for a fellow CR regular here it goes :-)
1. obviously: inststall ML
2. probably less obvious: enable "dual_iso" module in the ML menu
3. in the expo menu, enable "dual iso" and set the 2nd iso to use. I usually set the camera to fixed iso 100 and set ML to either 800 (=2.5ev gained) or when push comes to shove 1600 (=3.0ev gained). Then I expose for the highlights, i.e. I dial down ec to -2 or -3 until the highlights aren't clipped anymore - check the ML raw histogram for that.
4. you end up with an interlaced file DUALxyz.cr2 (if you've set the prefix option in the dual_iso menu). You then have to run a post-processing utility "cr2hdr" on the file to get a non-interlaced 16bit raw dng you can import into your postprocessing software.
Get cr2hdr.exe here (Mac/Linux also available somewhere): http://www.magiclantern.fm/forum/?topic=7139.0
The drawbacks of using dual_iso are:
a) it's harder to check for focus in camera because the image is interlaced
b) it's impossible to check for colors because they are screwed before processing with cr2hdr
c) postprocessing hassle, esp. time required for cr2hdr processing
d) dual file storage because you want to keep around the original cr2 in case cr2hdr receives further improvements
e) results usually needs manual wb (esp. tint) setting even though cr2hdr tries to autodetect it
f) if you use it regularly, you really wish you'd have a Nikon with native 14ev @base iso
All in all, I tend to use dual_iso very often, it simply saves me all the 2x brackets I used to do before and had to assemble with a hdr software, accepting the problem with frame differences like moving leaves or grass. I cannot believe how limiting it was to be stuck with the 10.5ev of my old 60d now that I can use 14+ev to capture shadows and bright sunlight in one frame.