The Online Photographer has a very interesting post up comparing the Sony A900, the Nikon D3 and D700, and the Canon 5D Mark II. TOP usually doesn’t get into such potentially controversial territory — at least as far as camera brand loyalists are concerned — and it’s a very interesting post.

Luckily, to avoid pissing off any one faction on the Internet too much, Mike is able to recommend each of the cameras in one way or another. He says the Sony A900 wins for “the ultimate in image quality,” although he says that it’s not perfect for every kind of photography.

But between its staggering resolution and very good dynamic range, its willing response to the Exposure and Recovery sliders, and its more “photographic” image quality and lack of digital artifacts—and despite its less-than-accurate color—it’s the IQ emperor for now, among these four (i.e., the three under discussion and the D3).

But he also mentions that if you don’t need the A900′s whopping megapixel count, then it shouldn’t really be in the running.

Up next is the “most recommendable” camera, which he says is the Nikon D700.

Given its sensible size compared to the D3, robust build, fast autofocus, overall responsiveness, superior ergonomics, unmatched high-ISO performance, and perfectly sensible file size, it’s going to be the most bang for the buck for more photographers than either of the others. The Nikon is flat-out a better camera than the Canon, a point exemplified by its clearly superior autofocus performance…. my feeling is that it would help more photographers take better pictures in more situations than either of the other two.

That leaves the Canon 5D Mark II as the “best compromise” between the A900 and D700. The 5DMkII doesn’t have the almost-ridiculous resolution and detail of the A900, but it’s up there. It also doesn’t have the high ISO noise performance of the D700, but it’s good. And, while it isn’t as good as the two leaders in those categories (in this comparison) it’s overall much better balanced:

And here’s the thing: [the 5D Mark II] has much more resolution than the Nikon, and much better high-ISO capability than the Sony. So its win over the Nikon where resolution is concerned is bigger than the margin by which it loses to the Sony in the same department, and its win over the Sony in high-ISO performance is much more decisive than the margin by which it loses to the Nikon on that score.

So if you giving each camera a score in both image quality/detail and high ISO capabilities, the 5D Mark II wouldn’t win either of those categories, but if you add them up to give you a total overall score, it would win. He makes sure to point out that he’s ignoring the strong video capabilities of the Canon 5D Mark II, so if you have a use for HD video in your DSLR, this becomes a much easier decision to make.

Then come the image quality issues with the 5D Mark II, which include some unusual chromatic aberration results that I haven’t seen mentioned in other reviews so far:

It’s been eight or 10 years since “purple fringing” (also called “CA,” not entirely accurately) first heaved into our collective consciousness as a peculiarly digital anomaly, and since then, other artifacts have been dealt with in their turn. I don’t see much in the way of purple fringing at all from the 5D Mark II, but there’s what Carl Weese calls “blue replacement,” by which narrow objects imaged against a brighter background change from their own color into a darkish pastel hue. You see it most often in twigs and telephone lines. The 5D Mark II isn’t particularly bad, but it shows up a lot more than it does from the D700. And its susceptibility to blue replacement makes it a candidate for a lovely lens aberration that I’d never actually seen before in a picture I’ve taken myself—longitudinal chromatic aberration (LoCA), which shifts objects in front of the plane of best focus to magenta and those in back of the plane to green.

There’s a sample photo from the 5DMkII showing all sorts of ugly purple and green branches, which makes me feel a little bit ill inside. I’ll try not to lose my lunch all over your shiny new cameras.

Mike also feels that Canon’s noise is blotchier than other cameras, and says that the highlight clipping is harsher and “less fixable” on the 5DMkII than on other recent cameras, and describes it as the kind of thing we would have seen a few years back. And, of course, the much-discussed black dot problem to the right of blown highlights. Mike somehow manages not to turn into a raving photography forum inhabitant with his reasonable downplaying of the black dot issue:

This doesn’t bother me at all—you’d never see it in prints and you probably wouldn’t notice it if it were visible—but hey, I’m just a reporter, I gotta report what I see.

I think we can be reasonably certain that Canon will fix this in a future firmware update.

Overall, a very interesting comparison between three excellent cameras, and I recommend everyone go visit the site and read the full review.