Which standard zoom for the K-5

Right I got a few primes, I got the amazing 50-135mm I got a 10-20 Sigma. However no matter how hard I try there are times when I just need a 16/17-x0 .

I do have the 18-55 WR kit but I do not particularly like it (sorry to everyone that raves about it) and I would like the 2.8 aperture.

I am open to suggestions but given the amount of lenses I own currently (40mm and 35mm the 21mm) I do not want to spend a heck of a lot of money which almost rules out the 16-50 unless there is a very good reason to get it over the alternatives.

So from the 17-50 Tamron, 17-70, 17-50 Sigma which would you go for? Are there other options I am not aware of?. BTW I had the Tamron in Nikon fit and though the IQ was really good the AF speed left plenty to be desired.

Well the Sigma 17-70mm isn't a constant 2.8 so you can probably rule that one out. Not tried the Sigma 17-50mm but I have the 16-50mm and just purchased the Tamron 17-50mm (actually arrived today) for my 50D.

I really like the 16-50mm even though most reviews seem to put the Tamron ahead for pure IQ but I am looking forward to having a play with the 17-50mm on the Canon to see how it performs (AF speed seems fine but then I am used to Pentax speed anyway so mostly anything seems fast to me).

What about the Pentax 16-45? Only f4, I'm afraid but I have an excellent copy for sale currently in the classified!

Dave

If f4 was an option then I would be buying the Pentax 17-70mm.

Id like to keep the option of shallow DOF there and this is why I am more interested in 2.8 lenses. Would you go for the f4 Pentax 17-70 over the 2.8-4 17-70 Sigma Mike?

I am quite a fan of Sigma but in this case (and having had both) I would choose the Pentax lens. The Sigma is a good and it's close up capability is handy but the Pentax gives richer colours and has the better build.

I got the Tamron 17-50 at a good price. I haven't used zooms much in the past, but thought I would give it a try. I haven't used it that much, but initial indications are that it's a decent lens. It has a satisfactory build, bulky but not really heavy. The AF works, I haven't had enough time with it to test AF shortcomings.

In terms of IQ, it's one of those lenses that is world class in the centre at all apertures(ie. as sharp as good primes, I'm not joking)but is not so stellar in the borders, although even there it's good. I got some annoying CAs at 17mm f2.8 which I couldn't get rid of easily with Lightroom, but that may be my lack of skills.

Overall, a good lens and terrific value. I did hear all sorts of horror stories about decentering etc. however, so I tested mine before I committed.

I find it hard to take my Sigma 70-200 Hsm 2 macro off the K5!!!
From birds in flight to close ups to sports photos it's great.
bb2

A bot OT but glad you enjoy your 70-200

I use a Tamron 17-50 on my K-5 and am very happy with it. It's comparatively small and light, has excellent IQ and balances well on the K-5.

I looked at the Pentax 16-50 but didn't go for it as I don't need weather sealing and didn't think the improvement in build quality was worth the difference in price.