Magic Lantern has just announced the ability to add three stops of dynamic range to the Canon EOS 7D and EOS 5D Mark III digital SLRs. For those of you who haven’t heard of Magic Lantern, it’s a, “software enhancement,” for Canon DSLRs that you install via your memory card. It runs alongside the camera’s firmware and adds new software features like focus peaking, HDR video, intervalometer, and most recently, RAW video. The new Dual ISO feature increases the dynamic range of the 7D and 5D Mk III to about 14 stops – significantly better than what you can get out of the stock cameras.
So how does Magic Lantern accomplish this impressive increase in dynamic range? Magic Lantern figured out how to make the cameras alternate ISO so one line is scanned at a low ISO and the next at a higher ISO. The resulting capture combines both for photos and videos with increased highlight and shadow detail. This works for both video and stills with the EOS 5D Mark II, and for still photos with the EOS 7D. In Magic Lantern’s sample (above – photo credit: Luke Neumann / Magic Lantern), the bottom left of the image was taken at ISO 100. The top right was taken using Dual ISO at ISO 100 and 1600. You can very clearly see the difference between the two sides of the image – especially where both parts meet on the Batman figure.
Of course, there are some downsides to Magic Lantern’s Dual ISO hack. It decreases resolution in highlights and shadows, increases moiré problems and you can’t zoom in to check focus in Live View. In the original Magic Lantern forum post announcing Dual ISO, there’s also a paragraph in red text with the title, “Warning.” It says: “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.” So, use it at your own risk.
There’s also the broader question of whether you want to use Magic Lantern’s firmware hack* at all. It does mess with the camera’s firmware and if it damaged your camera, it would not be covered under warranty. On the other hand, Magic Lantern has been around for a few years now and there are thousands of photographers and videographers who swear by it. It seems like Magic Lantern has made a pretty stable product.
If you want more information on Magic Lantern’s new Dual ISO feature, you can read their original forum post about it, here. If you want to dig even deeper, they have a complete white paper on Dual ISO, here.
*Magic Lantern doesn’t like the word “hack” applied to their software: “Magic Lantern is not a “hack”, or a modified firmware, it is an independent program that runs alongside Canon’s own software. Each time you start your camera, Magic Lantern is loaded from your memory card. Our only modification was to enable the ability to run software from the memory card.”