In what initially seemed to be an April Fool's Day joke, Magic Lantern released an experimental 4K RAW recording build for the Canon EOS 5D Mark III. As 4K RAW has long been the Holy Grail for 5D owners, shock immediately shifted to a frenzy of activity as users downloaded the build and began to experiment with it. 

The build adds the following resolutions to the 5D MKIII:

  • 1920×960 @ 50p (both 1:1 crop and full-frame – 3×3 pixel binning)
  • 1920×800 @ 60p (same as above)
  • 1920×1080 @ 45p and 48p (3×3 binning)
  • 1920×1920 @ 24p (1:1 square crop)
  • 3072×1920 @ 24p (1:1 crop)
  • 3840×1600 @ 24p (1:1 crop)
  • 4096×2560 @ 12.5p (1:1 crop)
  • 4096×1440 @ 25p (1:1 crop)
  • Full-resolution LiveView: 5796×3870 at 7.4 fps (128ms rolling shutter)

4k_magic_lantern_screen_shotRAW, but at 12.5p and No AudioCredit: Courtesy of Magic Lantern

Some of the immediate issues highlighted in the announcement by a1ex of Magic Lantern:

  • It feels quite buggy. I’m still hunting the issues one by one, but it’s hard, as Canon’s LiveView implementation is very complex, and our understanding on how it works is still very limited.
  • Write speeds are high. For example, 10-bit 4096×2500 at 15fps requires 180 MB/s. 1080p45 should be a little more manageable at 111 MB/s.
  • Canon preview is broken in most modes; you need to use the grayscale preview in the raw recording module.
  • High-resolution modes (in particular, full-res LiveView) may cause trouble with memory management. This is very tricky to solve, as we only get 3 full-resolution buffers in LiveView, with restrictions on the order in which they must be freed, and lots of other quirks.
  • Since these settings were pushed to limit, the risk of corrupted frames is high. If it happens, decrease the vertical resolution a bit.
  • When refreshing LiveView settings, the camera might lock-up (no idea why). Pressing MENU twice appears to fix it.

This is a "very rough proof of concept." It records RAW, but at odd, non-standard frame rates and resolutions (due to limits as to how fast the 5D MKIII can write data to the memory card). Before you download it, head over to the Magic Lantern Forum, read the threads, and make sure you're up for the adventure. The build is experimental, constantly being updated, and the list of potential issues is not for the technologically faint of heart. For example, this build modifies "low-level sensor parameters that are not well understood. They were all figured out by trial and error….As usual, if it breaks, it's your fault, sorry." Remember that running this will probably void your camera warranty.

Have you tried the build? What do you think? Let us know (and post some video!) in the comments.

Featured image courtesy of Canon

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