Viewfinder
Both the Canon 1Ds Mark III and the Nikon D3X have bright, crisp optical viewfinders. Both cameras offer 100 percent coverage through the viewfinder. Both manufacturers have much improved their viewfinders over the years, improving finder screens, prisms and so on. It's an advantage that both the 1Ds and D3X are nominally full-frame: the viewfinders' optical systems have larger images to work with than APS-format cameras. We used both cameras with 50mm f/1.4 lenses, 100mm f/2.8 lenses, and with wide-to-moderate zooms. The prime lenses are directly comparable, but the Nikon zoom we used was, at f/2.8, a stop brighter than the Canon. With the primes, we found the two cameras very comparable. The viewfinders were similarly bright and easy to focus. The images snapped into sharpness in even in low light, and even with low-contrast subject matter.

The 1Ds has separate analog scales for ambient and flash exposure. The D3X has a single scale for ambient. Both viewfinders show exposure values, frames remaining on memory cards, remaining buffer capacity, ISO, flash status, exposure compensation, focus confirmation, meter mode, battery status, exposure lock and so on. Both show AF points, and light up the selected ones. The D3X has a tilt indicator.

Canon 1Ds Mk III	Nikon D3x

LCD Screen
Both the Canon 1Ds Mark III and the Nikon D3X have 3-inch LCDs, but the Nikon has 920,000 dots and the 1Ds has 230,000. The difference wasn't all that noticeable. We found the 1Ds's LCD a better match for our (calibrated) computer monitors, though – both color and brightness matched better than the Nikon.

Canon 1Ds Mk III	Nikon D3x

We don't trust either LCD entirely. In photographing events and portraits – our kind of shooting – it's usually not practical to open images in Photoshop during a shoot to see real histograms or to check numerical values for highlights and shadows. Failing that, we have to rely on the cameras' feedback – how the images looks on the monitor, the blinking highlight warnings, and the histograms.

We have generally found that on both Canon and Nikon cameras, the highlight warnings and histograms are useful but not perfect, and the general look of an image can be misleading. For our kind of shooting, both cameras demand a fair amount of experience to learn the cameras. That's reasonable for wedding shooters and photojournalists, but for product and studio photographers, it's not.

Our test results show that the D3X and the 1Ds do not excel in dynamic range performance the way they do in resolution – they're not as good as many lower-resolution cameras. It seems to us that both the Nikon D3X and the Canon 1Ds Mark III beg to be shot tethered because the cameras don't give good enough feedback about image quality for their target market. Worse, Nikon charges extra for the necessary software. Clearly, plenty of photographers shoot with cameras tethered – even tethered wirelessly. That can be an efficient and flexible way to work, but there are situations in which it is not ideal. And if you're tethering an $8,000 camera because it won't tell you what you need to know about the files it's making, then you have an $8,000 camera with an ugly kludge.

We don't know what the ideal system would be, but we have a few ideas: Allow users to customize the highlight warning. Display numeric RGB data on the LCD, akin to Photoshop's Info window. Offer larger histograms – they could even be scroll-able. Compute histograms for a selected area of the image. Clearly, we're not camera designers, and we don't know the challenges involved in providing these options. Still, as we look at the Canon 1Ds Mark III and Nikon D3X, we see gaps between the cameras as they are, and the tools that would meet photographers' needs.