Aperture 3 bad raw conversion with Canon files

Question

Hi, Aperture is converting my 6400 iso raws into images I can't work with to my satisfaction. For pleasure I shot a staged disco dance event with some fun colorful lighting. When imported into Aperture via card reader the previews look somewhat similar to the Rebel's LCD jpg rendition.
One example, the stage light beams which are enhanced by smoke machines have one light with blue and another with magenta. When I click on that preview, the spinning wheel appears as usual saying loading which I believe is applying Aperture's interpretation algorithms. The results are stripping all the magenta and no matter what I do with the controls such as enhancement I can't get back the correct color. Remember the first loaded preview are similar to what I see in camera.
I rarely shoot this high of iso and I'm finding adjustments with highlights to be extremely sensitive with a much lower threshold of adjustment. On most of the previews I attempted adjustment I preferred the look before Aperture converted them. Clicking "M" for master does not revert back to what I first saw before selecting it. I can't get back to that original first imported look. I can see the differences in the previews side by side, one I click on and a similar shot I didn't.
I have never had this criticism before with this camera at 100 iso though it is recently acquired by a few months and never had this complaint with any of my NEF Nikon files. At first when beginning import the preview widow scrambled the order of the files where some images sat besides other images taken at an entirely different time. I closed everything and restarted and at first it did it again then corrected the order to which I hit the import button. I kept the images on the card and now will reload them directly onto my HD first. I'm reluctant to load into Aperture directly until I figure out what is going on.
I did download Canon's DPP processor and it did hold onto the colors that you see with the thumbnails you see to the left of the selected image. Go figure. I have not touched any of the import settings in preferences.
Your suggestions appreciated.
John

Answer 1

So what you're seeing initially at import is the JPEG that the camera generates as a preview for the image. All RAW files have this; the JPEG is what's used by the camera itself to give you the preview on the back of the camera.
When Aperture imports, it will initially show you the JPEG. Then, once it renders its own version, based on the raw converter built into OS X, it will show you that updated preview (which is also a JPEG). From that point on, that's what you'll see, and you can't get the RAW-embedded JPEG again.
If you use Canon's DPP, you're going to get a rendering that looks like what you saw on the camera, because they have access to their algorithms that they use for RAW->JPEG conversion. Apple doesn't have access to this; they make their own raw converter.
It may be possible that there are issues with Apple's raw converter in specific circumstances (i.e. high ISO images on a certain camera with heavy magenta or odd lighting). You don't say what version of Aperture and OS X you're using, but it looks like it is not Aperture 3.6 + Yosemite. It may be worth upgrading to see if  it's something that's improved (an easier way is if you have access to a machine with Yosemite, just open one of the RAW files in Preview, as that uses the same raw converter, to see if it's better).