Keith is right in principle -- I'm not sure he's 100% right in practice. If you search this forum and the Web you'll find that some people report that Aperture uses some of the WB information in the metadata to render the Image (Canon), while others report (as Keith states) that Aperture does not.
I don't know. I always use AWB. I record only RAW files. The WB I see in Aperture is usually excellent (so much so that I stopped using gray cards and my X-Rite Passport). But for sunsets and sunrise, and red flowers, the WB is far from what I want.
I treat WB as an artistic decision. Most people's vision is so far from purely ocular that rendering things as they look to a light recording device is not desirable.
Here are links to articles I found very useful when I was puzzling this out:
I just looked through my Canon 5D MKII raw pictures - no sunrise pictures unfortunately. The closest I could get, is this record from our recent experiments, nothing artistic:
But I noticed that the recent raw update treats the white balance settings differently for the Canon from previous raw support versions. The screenshot above shows the original image, taken last year, with a warning that the raw support has changed, and if I want to reprocess. The image to the right is the same image after reprocessing, and it has a slightly blue-green tint after reprocessing the raw.
Thanks for the responses. I haven't been quick to respond because I am traveling in the soutwest currently and don't have internet at every site.
I have reada few post on this forum about issues with a green cast to raw images taken with some Cannon's once they were processed by Aperture, but I hadn't really noticed much of an issue until I got to the soutwest. I don't know if it's becaise of the altitudes(6,000 - 8,000 feet) or the predomance of reds in the landscape, but I am sure noticing it now. Much like leonieDF's example. I am looking at them on my MBP's 17 " screen, but I suspect my monitor back home will show the same cast.
I guess I was expecting Aperture to adjust the white balance towards the shot setting. But it sure doesn't seem to pay any attention to the white balance setting of the camera ( Canon ), in fact it might be going in the opposite direction.
I did go through the links Kirby suggested. I had read the Cambridge article before, but it was a great reminder.
Thanks again for the replies.