On a 5D Mark III, when shooting mRAW

[Harv]

On a 5D Mark III, when shooting mRAW, does one give up anything other than resolution? I shoot motocross events most weekends during spring and summer. I have mostly used my 1D Mark IV and have been very happy with results. However, I have had occasion to use my 5D Mark III and notice a higher keeper rate on fast-closing, oncoming shots when compared to the 1D Mark IV. I would like to use the 5D Mark III more but don't like the very large file sizes it produces when dealing with thousands of images. It really does slow down the file transferring and processing. As I have full access on the motocross tracks and can literally go wherever I want, my images are pretty much frame filling or close to it. I need to do very little cropping, if any. That being the case, shooting mRAW would be more than adequate for my needs in terms of pixels on the target, but leaves me wondering if doing so would cost me more than the just the reduction in resolution. Can anyone comment on this concern?

[Skirball]

I'm not sure what they're doing on the 5d3 specifically, but in general mRAW is more than just smaller.  I can't say I've compared the difference myself, but I've read that mRAW loses some dynamic range, has some color shift and more noise.  All that said, it's hard to tell if it's a significant difference, or more internet test chart nonsense. There's only one real way to tell if something like this works for you - go shoot with both and compare them for yourself.  If you like the results then you have your solution.

[TCampbell]

Since RAW images are larger, they take up more space (even mRAW) and take longer to write to the memory card as compared to JPEG.  If you're doing rapid continuous shooting... you'll have the ability to capture more frames of JPEG (and actually I think the 5D III specifically is unlimited when shooting JPEG -- it can write the images to the memory card as fast as the camera can take them such that it should never exhaust it's internal memory buffer space.)

Of course... JPEGs are 8 bit and you loose latitude for adjusting the image in post processing -- hence the strong bias to use RAW.

Another limitiation of mRAW is that depending on what you use for imaging processing software, it may not recognize the mRAW files from your camera.  Since RAW is more of a "concept" and less of a "standard", the ability to read and process a RAW image requires special support for the RAW file.  When companies provide their camera RAW support, they don't necessarily include variant formats such as mRAW.  If you're using something other than Canon's software to process your images, make sure it can handle the mRAW files.

[ebiggs1]

It seems to me to be almost oxymoronic to buy a $3500 camera, 5D Mk III, or a $7000 1Dx and than use it lesser settings. But I suppose there are certain situations where one would see it as a reasonable solution. Must be why Canon put them in! Huh?

Personally I either use RAW, if I want the best photos or I use jpegs if I don't.

Since they both are CR2 files, I can't think you would have any problems reading them in any software that reads those files.

My lord not again but “... go shoot with both and compare them for yourself.” is the only way to know for sure.

[Harv]

Thanks for the input, folks.  Given what you have said, I'll likely stick with the full RAW.  I was just hoping to save some transfer and processing time, but it may not be worth doing.