[starstuff]

Does anyone have experience with these lenses for side-by-side comparison? I want to get an ultrawide for my K5 and don't want to deal with the size and weight of one of the ultrawide zooms, and so it seems that these two lenses are really the only game(s) in town. The DA 15mm is ideal in size and weight (I already own the DA 40mm and DA 21mm and love them), but I'm very attracted to the idea of the Sigma since, with its being a fisheye, it's actually more like 14mm (or even 12mm, some say). And it doesn't look all that much bigger/heavier than the DA Limited. Any thoughts, experiences? Thanks

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Last edited by starstuff; 06-19-2012 at 07:35 AM.

[elho_cid]

You just can't replace rectilinear ultra wide lens with a fisheye. I tried to do so and failed. So in the end I got both fisheye and DA14/2.8, both used for different purposes.
Even if you are willing to de-fish each image you take, you will never be able to frame precisely, because you don't know exactly in advance what will fall off during crop. You will end-up having effectively 6mpix images instead of 16mpix images due to losses in defishing and cropping. Using filters is another pain with fisheye.
DA 15 excells in shooting against bright light sources, even sun in the frame looks great. Not so with the FE.
If you want a FE lens, buy it, it is fun. But it is simply not good replacement of non-fish wide angle.

[wasser]

I have a Pentax 10-17mm FE and the DA 15mm. I pretty much concur with elho_cid. Get the fisheye for the fisheye, not to defish it. The Sigma takes filters in the rear. The DA 15 take normal 49mm filters, though you have to watch out for vignetting.

Of course there are other options, but they'll all be bigger. IMHO, if you want a small wide-angle, then the DA 15mm is perfect. If you want a small and fishy lens, just be sure you can live with the quirks of the FE, then get the Sigma, which is impressively compact for what it is, but still larger and heavier than the DA 15mm.