Canon 5D Mark III with Canon EF 24-70mm f/2.8L II USM Zoom LensLong Answer: Nope. There seems to be a lot of misunderstanding about what is actually happening with the new Magic Lantern hack in development that enables RAW Video output on Canon DSLRs. While it seems like some sort of magic on the surface (and it basically is), the reason this is possible is because of the RAW data stream that the camera is already outputting during normal operation. Read on for a clear explanation as well as some words from the Magic Lantern team on how this affects your camera.

One of the testers, g3gg0, posted this recently:

Meanwhile alex refactored all the code and optimized buffering, so that we are able to record 14 bit raw bayer data. the result is a module named 'raw_rec' which he highly optimized to get the maximum out of our beloved canon cameras. 

Our focused target is the 5D Mark III, but the devs are porting it to other models as you can see (thanks 1%, coutts, nanomad) 

Yet this code is EXPERIMENTAL. It will cause any random failures that lead from data loss to crashing cameras. As you know, ML is very stable, but sometimes code at this early stage causes unforseen problems. Prepare yourself for that before you go shooting. (a backup CF card, ML-free SD card)

Key ingredients:

- canon has an internal buffer that contains the RAW data

- we understand the high speed DMA controller "EDMAC" a lot better now and know how to crop areas out of an image

- we know how to get the maximum rate out of the CF card and so achieve to get up to 90MiB/s

- we provided a reference tool that converts the Magic Lantern .RAW movie into single .DNG frames plus a MJPEG script

All together sums up to the most advanced 14-bit RAW recording system people can get for less than 3 kEUR. We will prepare a full article as soon we see this code being stable enough for public testing.

Later, he mentioned what was clear to some from the start, but it's worth going over again:

About sensor heating rumors:
The only thing that could get warmer is DIGiC and the CF circuitry, but i am sure that the power dissipation that reaches the sensor
through all that plastic housing will not have any noticeable temperature raise.

detailed: when doing that much DMA transfers and CF writing, we may cause a bit more current drain (which causes squared power dissipation)
but we do not encode any H.264 while recording, so we use less power there.
its *possible* that the CF writing will consume less energy than the encoding with H.264, which will result in *less* power consumption.
raw is being produced by the DIGiC for every single frame anyway. we "just" save it away.

still this is a *theory*, but i expect the consumption and the temperatures not to raise at all.


In Live View mode, the Canon cameras take all of the pixel information and scale it down to a usable video resolution (how exactly they are doing this, only Canon knows, but not all of the cameras are doing it exactly the same way -- some might pixel bin, line skip, or a combination). This usable video resolution is still in a RAW form, which means if you looked at it as-is, it looks terrible. RAW sensor data with most single sensor cameras (like DSLRs) is missing a ton of information because each pixel only represents one color (Red, Green, or Blue). This missing information is then interpolated later by surrounding pixels, and that's how we end up with something we can actually look that (which is also the reason it's helpful to start with more resolution than you need on single sensor cameras).

To put it very simply, Magic Lantern found a way to access that RAW data stream from the sensor before it gets to the LCD or the H.264 compression. What does this mean exactly?

The camera sensor is doing no more work than it was already doing in Live View -- even if you aren't recording anything.

When you're recording the RAW data, the camera is no longer compressing the image to H.264, which is normally a very processor-intensive task and requires a decent amount of power. Anything requiring power generates heat, and the harder it works, the more power it needs, and the more heat it generates. With this process no longer happening in the camera, there is a power savings, which in turn means a reduction in heat for that process.

The H.264 compression, at its least compressed, is around 10-12 Megabytes per second, but since we are dealing with much higher data rates (around 83 MB/s with 14-bit 24fps 1080p), the CF card itself has to work a bit harder. This may cause some extra heat, but we should keep in mind that it is still within the spec for CF and the cards. We aren't overclocking anything, and stress testing for these components and this hardware likely goes well beyond what would happen in a normal environment.

The camera is doing around the same -- maybe a little more -- work overall than it would normally be doing while shooting video, so if you've had overheating issues in the past with a particular model, you will probably face them once more. This is not because of Magic Lantern, but because of the hardware in your camera.

So will your camera explode? No, it won't. Does that mean everything is going to work perfectly recording hours of RAW footage every day on end? Not necessarily, and more testing certainly needs to be done -- so if you're worried about your camera, you always have the option not to install Magic Lantern. The Canon 5D Mark III will likely be the most stable, as it is the newest technology and video was intended to be included right from the start.

Those who have been proclaiming doom and gloom should read a bit more into the situation before explicitly stating that cameras are going to blow up just because we're shooting RAW video.

Link: Uncompressed 14-bit Raw Recording -- Magic Lantern Forum