Sigma EX 18-50/2.8 or Pentax 16-45mm

Hi guys I'm looking for a good all round/everyday lens to replace the Pentax 18-55mm on my K10D. I wondered if the Sigma EX 18-50/2.8 would be as good or better than the Pentax 16-45mm... And which I should go for.
Any other suggestions would be appreciated as well. I have a budget of £300.
cheers Lee

Your choice will depend on how much importance you, personally, attach to the differences between them:

Price

Size and weight: The Sigma is considerably heavier.

Speed: The Sigma is faster by one stop.

Optical quality: I'm biased, but I would expect the Pentax to be superior, and it will also be a better match to your other Pentax lenses (assuming you have some!).

Range: The Sigma goes further; the Pentax goes wider.

Possible incompatibilty: Never buy a Sigma lens without positive confirmation that it will work not just with your camera body, but with any other body you might acquire.

It's also worth considering that Sigma may bring this lens out in an SDM version. If they do, the value of yours will be reduced. And I wouldn't trust anything a dealer tells you on this.

Finally, for another couple of hundred quid you could have the Pentax 16-50 2.8, which offers great image quality, SDM focussing, weather sealing, and a slightly greater range than either of the other two. The K10D deserves no less.

Decisions, decisions.

G

Personally I've got nothing against Sigma lenses and, despite owning quite a few over the last decade plus, never encountered any compatabilty issues (the only compatability issues I've encountered with my Pentax system have applied to Pentax components when Pentax have abandoned support for them in later bodies).

However IMHO 16-45mm is a far more useful range than 18-50mm and that would make me favour the Pentax lens over the Sigma, despite it being a stop slower. If the Sigma was a 16-50mm F2.8 it'd be a different story, but I've been quite impressed with the Pentax 16-45 and it's very significantly better than the 18-55 kit lens.

Actually, my next question was going to be...
Is the 16-45mm alot better than the 18-55mm kit lens? Is it worth the upgrade? I do like wide angle a great deal and considered keeping the 18-55 and buying a 10-17mm instead. I can't afford both unfortunately.... hmm..???
Lee

I have the 16-45, 18-55 and 10-17 so should be able to provide some advise. I've found the 16-45 to be much better than the kit lens (I've owned two of these now and both have been rather underwhelming in use), especially with regard to edge and corner sharpness.

The 10-17 is a great lens but, because it's a fisheye, it's not used all that frequently - I use the Sigma 10-20mm much more frequently.

Thankyou for that advice... I think, with a small budget, and the need for a good quality all round lens, the 16-45mm would probably be my best bet to start with. I have a DA50-200mm already which I'm happy with. Then I'll save up for the 10-20mm perhaps.
The 16-50mm would be nice but a tad too much money.
Lee

I have a DA16-45mm with my Pentax K100D and used to have a Sigma 18-50mm EX with my Canon 300D.

Optically, the new Sigma 18-50mm EX Macro will be equal to the DA16-45mm. The old version, which I had, showed quite some PF. The range 18-50mm is not very useful, especially on a 1,6x crop camera. I missed the WA part, so I did not use it much. The DA16-45mm is used quite a lot by me. The WA range 16-18mm is very useful indeed.

Couldn't disagree more They may be as sharp as each other, may possibly be as resistant to flare as each other, but even then they'll never be the same. As to which one you'd prefer - that's down to personal opinion. But bokeh, colour rendition, contrast, vignetting - all these are almost certainly going to be different between any two lenses.
Whether you could actually say which was "better" might be another story...

Lens comparison is usually very subjective and not always quantifiable - ask any Pentax Limited owner
Matt

It is very personal, of course. The new Sigma 18-50mm EX is quite an improvement over the old version, which showed lots of PF.

But if I had the choice between the DA*16-50mm and the Sigma 18-50mm I would choose the DA*16-50mm simply because the range 16-18mm is quite useful.

BTW I am quite happy with my DA16-45mm.