Sage advice from Andrew above, try a few before you buy, they are all good options, the 10-17 being a bit more specialised and probably best left alone for now if you are just starting in ultra wide land. I like my Siggy 8-16 better than all of them including the Sigma 12-24 HSMII that I had for nikon, the 8-16 is very special. The easiest to use is the Pentax, it is as good as the Limited 15mm, save for a tiny bit of micro contrast and a lot less vignetting but the 15mm is not really the subject here? If it is I'd still take the Pentax zoom. The two Sigma 10-20's are very good, there is not much between them but I'd give the nod very slightly to the constant F3.5 version although it is more costly. Back to the 8-16, the same can be true of any very wide lens, I like Landscape (This all could therefore, not apply to you) and do most of my photographic work in the lake district, even there with some pretty large mountains to use as backdrops they fade into pinpricks with an equivilent field of view of 12mm at it's widest angle, in practice for my usage it is in reality a 12-16mm, not much range although very very good, it does however excel at big sky and vast emptiness subjects where you can use the 8mm (12mm EFOV) end to magical effect.
So in summary. No1: Siggy 8-16 for optics and versatility but it's a hard task master and you may be dissapointed initially, it's worth learning though.
No2: Pentax 12-24mm for all around usability with no real weak points in it's genetics at all (It really is very very good indeed!)
No3: The Sigma's, they too are all three of them very good four if you include the older FF 12-24.
No4: Suprisingly the Pentax LImited 15mm, sharp as hell but no better than the Pentax 12-24 or the Sigma 8-16 (It's Pancake-iness makes it more difficult to make a totally convincing wide). Vignettes like hell and only the one focal length but it is beautifully made and teeny tiny, gorgeous, beautiful, desireable AND ADDICTIVE!

The AP review gives it a glowing review for resolution, 36 whatevers, out of a maximum of 40 on their charts, the only thing higher being the D800 and then apparantly not by much. It does seem very odd that DXO would draw a conclusion without testing sensor resolution, in fact going by their analysis stats it would seem impossible? Must be a misprint/error in proofing or something, if not it will blow the whole mistique surrounding thfe DXO tests being a widely qouted industry standard. Maybe here is where I get my pay off regarding the K3 sensor? If I'm getting a little less Dr/ISO/and colour depth and it is only a little, I will be happily content with the resolution figures in my own mind.
It's nice to have a counter to all the photographers at Ashness Bridge! There was a bunch there last friday when me and the other half were out, looking down their glasses at us and then having little conversations and pointing when they realised I was not using a CaNikon. My retort then was "No I just don't like the shot! I'd rather do something original", and slowly putting my camera away and gently walking off up the hill to Falcon crag. The reaction was something like
Truth is I don't like the shot and just can't make it work for me, never have been able to...

Aww and there I was on the Ricoh/Pentax K50 color chooser thingy too. It's a fun way to spend a few minutes anyway, and I do like that mettalic blue.

Well I'd better tilt em back before I put em on my website then!

Still listed at SRS but don't know if that means anything or not. Price has gone up from £399-£549. Maybe just state side, they might have enough over there for current demand, and don't need to make anymore at present...

I think the kit lenses are ok for what they are but I hear you there Pentaxophile! It would not do Ricoh/Pentax a disservice to resurrect the 16-45 as the kit lens, and what a kit lens it would be!

But But I used the K3's Level...

Seriously though they were level but I reckon they may look better tilted slightly I'll take a look in lightroom later...

Hi Steve, it's not a dust bunny it's a little cloud, I thought it was dust too

[/quote]I've a K30 and I'm really impressed at how well it recovers both shadow and highlight detail - it's miles better than my K7 was. While the 14 bit on a K5 should be able to recover some more at either end, I really wouldn't see it as a selling point - I'm sufficiently impressed by the implementation of the sensor and processor in the K30/50 to be able to recommend it. I also love the blue colour of my K3 body [/quote]He He, I'd forgotten about the colour thing hmm

Beat you Robbie! https://www.pentaxuser.com/forum/topic/ap-review-of-the-k-3-46231

I think it deserves it's own thread though, Ed seems a nice guy. He goes off at a tangent sometimes but he gets his point across eventually, you get the feeling he feels he has to do it coz no one else is, doesn't look too comfortable in front of the camera but likes and shoots Pentax, the more the better...