if you're a wide-angle only guy, that's a good choice. But even a 12 isn't that wide on a DX body. A 10.5mm may be needed to really get wide (and correct the distortion in software if you like rectlinear wide angles). I just shoot extra frames and stitch if I want super wide.
The Tokina gets mixed reviews - decent lens, but not outstanding
http://www.photozone.de/canon-eos/272-to...-report--reviewsimilar results for the slightly wider Sigma 10-20mm
http://www.photozone.de/nikon--nikkor-ap...-review?start=1both are pretty sweet, but neither of these lenses interest me. My choice was to cover everything from 18mm to 200mm with two low cost lightweight Nikon VR lenses (18-55mm and 55-200mm), for a total cost of less than $300 (ebay Nikon refurbs). Both of these lenses get excellent reviews, especially for image quality (built is a different story, but that's how they can be so light)
For really wide stuff and extreme perspectives, I'd go with a Nikon 10.5mm or a Zenitar 16mm fisheye (and correct perspective in software if you want straight lines). Light, cost a fraction of the true big corrected lenses. There's a point when weight becomes a major factor and unless you're on a photo expedition and plan on doing a lot of special shots, you have to compromise, even if you can afford the good flat field super wide stuff.
(my 14mm f2.8 Canon was fantastic on my EOS full frame film gear in the 90s, but I'd never carry that chunk of glass and metal on the JMT, plus you can buy more than 10 Russian made
Zenitar fisheyes for one
of these, or you can get 100 Zenitars for one
of these. The software to correct barrel distortion is rather cheap at $30 -
http://www.kenrockwell.com/tech/fisheye-hemi.htm )
Another thing to mention about the cheap VR lenses I use - they give you at least 2 stops of extra stability. You're getting f2.8 shutter performance at f5.6, saving the weight of the equivalent ($$$) pro lenses.
Obviously, there are major optical quality differences, but at 12 megapixels you don't really resolve those differences, at least not the resolution part. Chromatic abberations can be corrected in software and color quality is relative (it's all fake anyway with RAW image processing these days). A 20+ megapixel sensor really would be able to record the difference between a $2000 pro lens and these cheap 3rd party or Nikon budget lenses, but for now I am at 12mp and that's plenty for my outdoor use.
Your D2 sensor already requires post processing for chromatic abberations (newer gen cameras do most of that automatically in-body), so you're looking at a lot of Photoshop work anyway, so why not get cheap glass and bend the lines straight if you want super wide. Even on a DX sensor, these fish-eyes will give you viewing angles wider than a 12-24mm tokina, and they are so small that the weight of the fisheye PLUS an 18-55mm will be about the same as the lone Tokina.
Guess this is all about compromises and knowing what you will actually use on your trip, so I better stop rambling, because there are dozens of other ways to look at this. Right now I'm doing the above, but on my next big trip I'll be doing a few things differently.
