Advice on a fast zoom lens

I am looking for a fast, preferably A/F, zoom, f2.8 across the range, from 24mm to 135mm or so, and was wondering if anyone had any recommendations? I need it to be reasonably sharp wide open across the range, and very sharp stopped down. Does such a beast exist?

I may be wrong but I don't think there is such a lens (in Pentax mount anyway).

Thanks, Mike, wishful thinking I guess! I'll have a look at something with less range.

TBH I think your only real choice is something like the Sigma 24-70mm f2.8 or Pentax/Sigma 50-135/150mm

That's how I covered it

Maybe the Tokina AF 28-70mm f/2.8-2.6 AT-X Pro II could be an option?

Bjørn

Tamron 28-75mm f2.8 comes to mind as well. They can be bought for a very reasonable price second hand and the IQ is really good.

Thanks for the suggestions, I really need 24mm at the wide end.....I will have a look at the Sigma 24-70mm. The 50-135mm is a bit large, so i will have to think about what to get for longer focal lengths, though the f2.8 is not so critical at the long end ie beyond 70mm.

By 24mm do you mean 24mm FoV or 24mm actual focal length?

Because if you need 24mm FoV the only real option is the DA*16-50.

If you want something with a wide zoom range then speed is the compromise like on the 18-135 which is 3.5-5.6 depending on the focal length.

Seeing as you have a K-5 do you really need the speed? You looking specifically for shallow DoF?

If you are than I'd say get the 16-50 and 50-135 pair. Pricey but well worth it!

I want 24mm (or less) focal length. At the moment I carry loads of primes to work with me, a 24mm f2.8, a 50mm f1.4, sometimes a 90mm f2.8, and a 135mm f3.5, plus a Sigma 18-250 (which I am going to sell). I have now got 2 cameras (one IR), and can't keep lugging around so much stuff. I have just bought a 35-105mm lens for infrared, which I use in the daytime only, but want the fast zoom for both day and night shots on the K5. It's the night shots that need the wide aperture; they will all be at infinity so DOF is not relevant, though it will be nice to also have the option of shallow DOF when I want.

This sounds fairly close to what you want: http://www.pentaxforums.com/userreviews/sigma-24-135mm-f2-8-4-5-aspherical-if.ht...
It's not 'EX' graded, but I've had one for several years and used it with a good degree of success.
The onboard firmware used to disagree with my *istDS from time to time, but it's been trouble free with my new K-R.

I think Mattmatic has a Pentax-FA 24-90mm for sale