DECENT A/F TELEZOOM WANTED

OK, I`ll apologise straight away, in that what I am going to ask has been covered in other threads at earlier times - but I`m trying to avoid trawling through.
I have a K20D with Tamron SP 17-50 f2.8 plus a recently purchased Pentax SMC 28-105 f3.2-4.5 (which was a good buy I think). I would like a telezoom that extends up to 300mm to complement these.
If money were no object I`d get the Sigma 100-300, but it`s out of my reach financially. So the choice is either the Pentax 55-300, Sigma APO 70-300, or possibly the Tamron 70-300. My prime requirement is for sharpness/image quality; I have no need for Macro and won`t hardly ever want to use `wide open` - more like f8-11. Nor am I bothered about weight or how far the barrel extends at the long end; most of the time it will be tripod-mounted. Built quality/durability is an issue though.
In reviews I`ve read, the Tamron seems to be the poorest performer, but every time I read that the Pentax is the best, along comes another one that says the Sigma will give the better image quality. So - help please!

I hear the Pentax 55-300 is a cracking lens (on my wish list)

Pentax 55-300mm
No contest really ... plus £25 cashback and free delivery from SRS.

Sorted.

Another endorsement for the DA 55-300. Superb value and very decent performance.

Nothing else comes close, it's also small and light, something the Sigma 100-300 isn't! .




I sold mine and bought a FA*300 f4.5, much smaller, lighter and way better IQ.

Ditto on the 55-300mm.
Fabulously sharp at 300mm. Not terribly fast, obviously an F2.8 would be dreamy, but for what I do this lens does not leave me feeling like I need anything more.

Don't get the tamron. The purple fringing on high contrast edges will drive you nuts. It's a pretty good lens otherwise, for the £60 it cost me at Jessops.
However today , I did a bad thing, ( according to my wife...)I bought the Pentax 55-300 from those awfully nice people at SRS in Watford and it really is a little gem. Even though it was dark when I bought it, the few snaps I have taken with it have much better colour and is MUCH sharper at the long end than the Tamron. I was hoping to point it at the moon tonight for a play but it's cloudy here!
I haven't used the sigma but have a look herefor wise words from someone who has.
Well worth a browse through that site by the way....
Now I'll have to put the Tamron and DA 50-200 on ebay to pay for it

thanks for the info so far guys. It looks like the Pentax 55-300 is out in front at the mo (and the £25 cashback helps too). But image quality is more important than the price of a few more pints, so is anybody going to push the case for the Sigma 70-300 APO before I `splash the cash`? All opinions gratefully received.............

I think the IQ from the Pentax 55-300mm is very likely to be better than the Sigma 70-300mm.

I've owned all 3 of your options & 100% recommend the Pentax 55-300 above the others, the Tamron & Sigma both have noticeable weaknesses (Tamron - PF & the Sigma is a little soft). The Pentax is a great consumer lens, sharp at all focal lengths, nice colour/contrast rendition and very little PF, it is a little slow but not really any different in this respect to the other 2.

Simon

I have a slightly older version of the current 70-300 Sigma APO which I got when the Pentax was new out and priced a bit higher. I had tried out the tamron and although sharp the PF was too annoying for me. I haven't tried the Pentax but from what I've seen it seems to be very impressive, especially for £189 with £25 cashback. I have been very happy with the Sigma though, very minimal PF and sharp enough for me a couple of stops down even at 300mm.

A couple of months ago places were selling the Sigma APO for £110 and I would say that is a good deal but now it is back up to £150 it may be worth the bit extra for the Pentax, beware the cashback ends soon though!

Well, I`ve done it now, and ordered the Pentax 55-300 from SRS - expected tomorrow. Naturally, I`m keen to see how the images compare with those taken on my old manual-focus zooms - Tokina 80-200 mm f2.8 and Ricoh 300 mm APO f4.5.