[osv]

My Tamron 28-75 does. The Tamron also focus down to about 7 inches, while my Sigma 85mm is closer to 2 feet.

that is not a useful parameter, in the context of this landscape lens discussion.

what does matter, tho, is the ability of a wide lens to render foreground anchor objects in focus, in a landscape shot, which is further out than 2 feet.

i checked for that with the fa35 vs. korean 35/1.4 lenses, and the fa35 was much better at it.

[btbsurf29]

Thanks for all the contributions. I hadn't given much thought about flare. I'll have to take that into consideration. The Sigma 10-20 is the most affordable of the choices. Ebay is currently having some attractive package deals for under $500. But the 15mm and the 12-24mm keep calling towards me. They both take some incredible pictures. I'm only an enthusiast and primarily take photos of landscapes and architectures. I think the 15 would be a nice addition because I enjoy using prime lenses and its so compact. But the focal length and quality of the 12-24mm is also very appealing because it would also be a great everyday lens. Decisions, decisions! Depending on my funds I'd like to pair the lens with a Singh-Ray polarized filter but I might have to settle for a Tiffen or Hoya.

[mikeSF]

I use all Sigma's and have never gone wrong with one of my favs the 10-20mm. I cannot praise this lens enough for landscape photography.

i too use the Sigma 10-20 for my ultra wide shots and like it

[Des]

I love primes but I prefer the flexibility of a zoom for wide-ultrawide shots. In many situations - such as standing on stones in a river, or in a dense forest, or inside a building - it is often impractical to zoom with your feet. That's why I went for the DA 12-24. It's sharp enough and renders colours well. The range is really useful - being confined to say 15 and 21mm would often be quite limiting. The downsides? Not WR, bulky, prone to flare.

With any ultrawide lens, expect a fair bit of distortion. Think about software too. I use DxO Optics Pro with the ViewPoint plug-in (easy to use, works well), but there are plenty of alternatives.

[bpv_UW]

I've used both the Da 15 (which I ultimately chose) and the Da 12-24 fairly extensively. I haven't used the 21, but I think it would be too narrow for my tastes in a place like GTNP.

Advantages of 15 are: size/weight, flare resistance, (a little) better microcontrast, overall rendering (admittedly subjective)

Advantages of 12-24 are: flexibility (primarily ability to go wider than Da 15 for landscape shooting), less field curvature (meaning easier to get solid corner to corner sharpness in a single image in shots where large DOF is demanded)

In my experience they are about equally sharp. People complain about the 15's corner and edge sharpness (I was one of those people for a long time), but that is largely related to high field curvature and thus focusing it to retain sharpness in all areas of the image is more challenging. It isn't that the corners are soft, per se.

At the end of the day, either has the ability to get you crackin' images. It's ultimately a decision of flexibility (zoom range of 12-24) vs. size/weight/flare resistance (15). I think convenience factor is about equal (12-24 much more of a pain to lug around, but 15 more of a pain to focus and depending on your needs and composition you may be doing more focus-stacking in post).

Enjoy your trip!

-Brandon