Pentax DA* 16-50 or Sigma 17-50 (both F2.8)

I'm seriously considering selling on my Samsung GX10 (almost 5 years old now!) and upgrading to a K5. Nothing wrong with the Samsung, but video, better low light performance and general picture quality are big draws for me.

At the same time I'd like to take a step up from the 18-55 kit lens, and I want one that is constantly fast through the zoom range. I'm sure this has come up before but I couldn't find it on the search, what is the general opinion on the Sigma vs. Pentax? They are similar enough in price (especially if I buy 2nd hand), so build and image quality is what matters!

I've not tried the Sigma, but I would not be without the DA* - it has become the "default" lens since I bought it a year ago. You could always hire the Pentax from SRS for the weekend and give it a go - that was what I did and placed an order as soon as the hire had been picked up.

There is a comparison of these (+ the Tamron equivalent) on the other Pentax forum and the Sigma came out top of the list there.

I don't have any experience of these personally but from what I've seen there is nothing between them for iq. The Pentax gains WR and a quick shift focus ring I think but there is a big question mark over SDM reliability which I think would put me off from buying second hand.

Any reason you've excluded the Tamron? That one seems to be cheaper than the others but with just as high iq.

I hadn't considered the Tamron, just didn't know it was available! I've just bought the Sigma from eBay for what seems like a pretty reasonable price, I found the discussion/review you mentioned and decided that Sigma was the way to go.

The nice thing about photography kit is that if I don't like it, they don't really lose much value and so I can easily resell!

Don't touch the Sigma, buy a Pentax.

With the K-5 you can get away with a slightly slower lens.

I bought a DA 17-70mm a couple of months ago and haven't used my DA* 16-50mm since.

I agree with Mike, I sold my DA*16-50 after I got a DA17-70 as it was smaller and lighter and had less vignetting when using the pop-up flash.

That said I now find that my preferred general purpose lens is the DA 18-135mm. When I need the best possible quality I use a DA limited.

It all depends on individual preference. I like to travel light. If you need a wide aperture zoom and do not mind the weight and bulk, the DA*16-50 is pretty good.

It's something interesting to bear in mind...

I am surprised. The 16-50 is noticeably better. In fact, it is so good it is nearly up the standard of Ltd lenses.

Pentax doesn't award stars for nothing.

The 17-70 is a good lens, but not in the same class. The only reason to favour it over the 16-50 is the slightly longer reach, which puts it into the general purpose category. If you are ambling around with only one lens, there is a strong argument for taking the 17-70.

G

I am not sure I agree that it is up there with the ltds but I love that lens... It feels sooo right in front of the K-5 and that 16mm is just about wide enough to get you by in most situations without needing to carry the 10-20

Not up there with the 50-135 but quite close. I love mine.

Don't get me wrong, the DA*16-50 is a good lens but for my purposes it is just too big and heavy as a general purpose lens. It is not that good at 16mm so if I want to go wide the DA15mm Ltd is a better bet. For general purpose use the DA 18-135 is smaller, lighter, focuses faster, has a wider range and gives sharp images in the centre where the action usually is.

Much of my photography is combined with travel, family activities, social events etc., which makes a versatile zoom a sensible choice. When I am doing more specific tasks, landscape, portraits and the like a prime lens is more appropriate. For my purposes the DA18-135 is much more suitable as a general purpose zoom. I like to travel light. Others will have different priorities.

It seems this is an interesting area for lenses where neither ultimate quality or ultimate versatility are the objective. I asked a similar question on fast zooms recently and got some helpful replies.

I'm now tempted to keep the 18-250 for versatility and buy a selection of primes for specialist jobs (already got the FA50/1.4 and a 300mm f4).

I completely agree with Archie. I thought many times of selling my 18-135, but I keep reaching for it whenever I am travelling or going for a walk.

The only thing that's wrong with it at the moment is the price. It should be around £250

I went for the Sigma 17-50mm f2.8.

I was put off the Pentax 16-50 by it's higher price and reports of failed SDM motors....

Guess what? Before long the focusing on the Sigma was atrocious and it had to go back to Sigma for a new auto focus motor. (UK 3 year guarantee, lens back with me in 12 days)

It STILL wasn't right though, so back to Sigma again this time for a "MR sensor", again, quick service.

That did the trick though ... quiet crisp quick focusing, reliable and rarely off the camera, used almost exclusively and I now have complete confidence in it.

I can honestly say that this is probably the best wide to medium zoom lens I have ever had.

Graham.

I have the DA* 16-50mm. My copy is very good at f5.6, goodish but starting to go at f8, poor at f4 and terrible at f2.8. 16-20mm and 45-50mm aren't great either, imho, particularly the wide end. Very good build quality, mind. Pretty grim CA in the right ie wrong conditions, not that good for flaring. Very good resolving power at f5.6, impressive. Lovely colours and contrast at f5.6 too. In fact, I am taking it back under the warranty for a check up or calibration as I've only had it a short while and the drop-off on either side of f5.6 is startling. If my copy stayed on song over a wider range of settings, so to speak, it would be an excellent lens and perhaps after a visit to the repair shop it will be.

Given how many folk seem to have quality or reliability problems with these xx-50mm f2.8 lenses, I wonder whether any is really worth it. A slightly slower xx-70mm sounds a bit of a safer bet and at least it won't entirely bust the bank. Shops are now asking around £879 for the Pentax. I think you'd have to be very brave to recommend it at anything like that price.