Wide angle options ?

Thank heavens she was on the way up...

Was that at 10mm?

Here's a shot of my brother taken with the Sigma at 10mm. No, his head isn't actually that shape.




Here's a shot from down your way Lilly, which shows the lens distortion (curved horizon) at 10mm. This isn't too bad in my opinion, but it's a little odd in that it's only at the ends that there's a curve. This disappears by about 12mm (ignore the red and blue box ).




Dan

You are a bad man, Christopher.

G

thanks Dan that illustrates what I wanted to know, in fact that horizon is no worse than the 18-55 at 18mm, very acceptable - brother's head demonstrates well not to go too close tho' (ps-wd have been a nice entry for 'motion'!)
thanks again everyone for yr help....Lilly

I'm pretty sure it was.

just thought I wd share this link I have just found, this link particular to the 10-20 Sigma, but amazing site to view images from other lenses etc..
ignore if you know of it already:
http://www.photosig.com/go/photos/browse?sort=id-d&page=1&id=36444

Yes, unfortunately I didn't think of this one, but I was about to enter the one below until I saw Niblue's entry, and I thought it was a bit too similar.



(taken with the 10-20 at 10mm again, just a couple of minutes before that other one. 1/10s, f/8 ISO400 with the *istD).

Curvature at the edges of the frame is more pronounced at 10mm, and I'm not sure if tilting the camera emphasises this too - here's an example:




But overall detail and excellent lack of CA's with this lens is superb.

Dan

My motion entry was also done using the Sigma 10-20, in fact both my successes in the competitions so far were with that lens.

I'd also agree the lack of CA with the Sigma is noteable - my two most commonly used lenses are the 10-20 and the Pentax 16-45. If I shoot at say 18mm and can't recall which lens I used there is an easy test: if there is any CA then it was the 16-45, if none then it was the 10-20.

Sharpness and colour rendition is also very good. While it's possible that the Pentax 12-24 might be better (although I'm not convinced it is) but IMHO it'd have to work miracles to make up for the price difference against the Sigma (£629 v £289 at warehouseexpress).

Perhaps.However, I paid just over £400 for my 12-24 and with that price difference I think the Pentax starts to take the edge.

Kim

I do quite a bit of (indoor) architectural photography and I chose the DA12-24 over the Sigma because in all of the photos I seem to see from the 10-20 there is what I would call an unacceptable level of distortion. Not nice, easy-to-correct-in-Photoshop distortion but the horrible wavy kind.

If you need straight lines in your photos then I see no competition; the DA has minimal (and very linear) barrel distortion at the wide end and no distortion at all (that's visible to the eye) at the 24mm end.

If on the other hand you want a WA for landscapes and nature shots where distortion is less of an issue, then the price and the extra 2mm on the wide end of the Sigma make it very tempting.

It's a horses for courses thing - neither would be a really bad choice but I do genuinely believe (and was prepared to back with my own hard-earned cash) that the Pentax is a significantly better lens.

Just my $0.02

Not for me - if the Pentax was under £350 I'd have considered it however at £400+ the extra £110+ isn't that far off the price of a new FA 50mm F1.4

This is what photozone has to say on distortions:

Pentax

The Pentax DA 12-24mm shows a pretty good distortion characteristic for an ultra-wide zoom lens. At 12mm there's a relatively pronounced degree of slightly wavy barrel distortions (~2.1%) which decrease continuously when zooming towards the long end of the zoom range where the lens is basically free of distortions.

Sigma

The Sigma AF 10-20mm EX DC showed a rather unusual distortion characteristic. At 10mm most of the image field is almost free of distortions so the measured distortions figures look fairly fine here (taken a little inward from the borders). However, this is only part of the truth. If you check the 10mm distortion chart below you will notice that the extreme corners are actually quite (barrel-)distorted - probably in the 2-3% range. At 14mm the lens shows a moderate degree of pincushion distortions, less so at 20mm.

So it doesn't look like there is all that much in it, especially given the the comparison is between 10mm in one case and 12mm in the other.

The Pentax tests a little better for vignetting, and MTF figures are fairly similar (and both quite good) and for CA the Sigma tests much better.

Overall they don't seem to thing there was much in it between the two lenses so as the Sigma is significantly cheaper and significantly wider that makes it an easy choice for poor people like me, however I'm certain I'd be quite happy with either lens.

I want a wideangle. At 10mm the sigma looks really good to me!

It is!

Dan