I own all three camera bodies. My thoughts:
1Ds: A groundbreaking camera when it was introduced due to the true 24x36 sensor. Wide angle freaks rejoiced. The Fish Eye was back in the game. The body construction was excellent, with excellent weather sealing. After initial excitement waned, users began to see noise patterns in dark areas, and high-ISO shots suffered from a grid-like pattern appearing on some bodies' images. The power supply wasn't perfect and if/when the camera locked up, the battery had to be removed to zero-out the camera's electronics. Even with these flaws, this camera rang the death knell for many photo labs around the world -- within two years of this camera's introduction, more then 50% of the "pro" labs in the U.S. were gone.
The Digic processor was at v1 and its design, implementation and improvements have become the cornerstone for Canon's imaging tools. The 1Ds and Digic 1 provided users with enough processing speed and data information (histogram, exposure info) that use of the camera in every professional condition was easy.
With the 1Ds, raw file processing came under close scrutiny and camps of photographers chose their software, some becoming vitriolic about others' software choices. Canon's software, Digital Photo Professional, was weak and this surprised everyone, causing mass migration of users to Adobe Camera Raw, Bibble Pro, Capture One and other programs. I chose to go with Capture One Pro and used custom ICC camera profiles generated by etcetera.com. Color & contrast accuracy was a breeze.
1Ds2: This camera brought a slightly improved body construction, a Digic 2 chip and a higher resolution, full-frame sensor. Everything that was good about the "Mark 1" was vastly improved on the Mark 2. The negatives mentioned above, noise in the shadows & power malfunctions, were virtually eliminated. Using ICC profiles from Etcetera provided me with outstanding color and contrast with minimal effort.
The Digic 2 chip brought faster file processing and a better signal-to-noise ratio. The results from this camera again pushed the envelope in image quality. If it hadn't been for the price (US$8000), I think most photographers world-wide would've migrated to Canon because of this camera.
1Ds3: This camera brings again an improved body design with better weather sealing, a redesigned power system, a Digic 3 processor, 14-bit color and higher resolution to the market. The ability to photograph 2-page spreads without interpolation is now available in the DSLR format. For many commercial photographers, this is the holy grail of resolution: less than 2% of my work requires larger reproduction.
The power system uses a Lithium-Ion battery and has even longer life and a much higher degree of battery evaluation to help determine the usable life of each battery.
To some, the small increase in resolution over the Mark 2 was not worth the upgrade. To me, the increase in resolution combined with 14-bit color was well worth the investment. This provides me with a significant leap in overall image quality and control. Although 16-bit inkjet printing is in its infancy, this camera's image quality provides digital display prints that were unattainable just a decade ago. It's not that colors are more vibrant, it's that gradients are much smoother, especially in very dark and very light tones. Pale caucasian flesh tones look wonderful.
The Live View function was something I thought I'd never use. I was wrong. I use it constantly. Most of my work is done with the camera on a tripod. It's slower, more methodical and allows my two brain cells to easily communicate with each other. With live view, exact focus is now possible, and this is a real treat when used with a wide aperture. In addition, the lenses can have a focus micro-adjustment made and registered by the user with each 1Ds3 body for exact focus. These two feature provide for outstanding still life work. In addition, focus micro-adjustment produces better results from hand-held, auto-focus photography.
5D: I have only toyed with the first generation of this camera. My concern, if I were where you are, is: will the body hold up under that environment? You're in one of the wettest regions of the world, and unlike northern Scotland, it's hot. If you think it'll work, then you'll save several thousand dollars, and that's not something to snivel at.
