[michael.colby]

Hello everyone!

I looking at getting either the DA* 16-50mm or the DA 20-40mm Ltd., but I'm really on the fence about which is better. Has anyone used both (or either) of them, and could give me some stronger details on their functionality? I've browsed around other forums, but I've seen quite mixed feelings. Any suggestions? Hope to hear from you soon!

Thanks so much!
Michael

[GaryH]

I bought both at the same time last year during the BF sale. I ended up sending the DA 20-40 back because I was concerned about its softness at 20mm and wide open. However, it does weigh 1/2 as much as the DA* 16-50 and has less CA. I am again in the market for the DA 20-40 as it would be nice to have the little zoom range for street photography. I think it is a decent zoom if it is a range that you can live with. The 16-50 is very nice too but is much larger.

[DeadJohn]

The 16-50 goes much wider (4mm on the wide end is a lot). If you like shooting wide angle get the 16-50. If you don't care about wide angle and prefer compactness get the 20-40.

[Crooski]

Look at this site under reviews. Where the sigma 18-35mm is reviewed.

see the Verdict of the sharpness test on this site.

If you do not need the wide angle and preferred compactness get the 20-40.

[godavari]

I use 16-50 extensively and I like the results. However, I had to send it to repair twice. One to get the SDM failure fixed and another time to get the stuck zoom fixed. Nevertheless, it is the most used lens in my kit.

[Rondec]

I guess I would prefer the 16-50, mainly for the presence of 16mm. There are plenty of times where it is awfully nice to be able to go out to 16mm, but most normal APS-C zooms only go to 17 or 18mm.

The 20-40 is smaller, more flare resistant and doesn't have the issues that you get with SDM (although there is a pretty easy hack now to change the 16-50 to screw driven).

16-50 at 16mm

[Marktax]

I think the 20-40 and 15 Ltd,'s are a better carrying pair than the 16-50, which has that large hood and requires a more expensive CPL filter. Most Pentaxians already will have a 49mm CPL, and a 55mm CPL is a lot cheaper that a 77mm.

[Moropo]

Sorry for sort-of hijacking the thread, but I have a quick question:

Is the SDM problem in the 16-50 present only in lens bought a couple years ago? In other words, if I buy a brand new DA* 16-50 from B&H, should I expect it to be SDM-problem-free because it was fixed in the new production batches?

[Rondec]

Sorry for sort-of hijacking the thread, but I have a quick question:

Is the SDM problem in the 16-50 present only in lens bought a couple years ago? In other words, if I buy a brand new DA* 16-50 from B&H, should I expect it to be SDM-problem-free because it was fixed in the new production batches?

I don't think anyone can answer that question. I bought my 16-50 in 2008. Four months after I bought it, the SDM failed. Fixed it under warranty and it has been fine ever since.

There are rumors that recent 16-50s have a new and improved motor, but since there has been nothing official that Pentax has ever said, even saying that SDM has a problem, then anything we say about is speculative, to say the least.

[Dice]

I've used both. I wouldn't hesitate recommending either but you will need to understand the limitations to assess whether they affect your photography.

[goodnight]

I don't think anyone can answer that question. I bought my 16-50 in 2008. Four months after I bought it, the SDM failed. Fixed it under warranty and it has been fine ever since.

There are rumors that recent 16-50s have a new and improved motor, but since there has been nothing official that Pentax has ever said, even saying that SDM has a problem, then anything we say about is speculative, to say the least.

There was that interview with the very friendly German engineer back at Photokina 2012, tho I'm not sure that qualifies as official.

Once the tour started, we of course proceeded almost immediately to the Pentax booth, which, unlike many other exhibitions, was practically ready to go and fully manned. There, we had a conversation with a very friendly German Pentax engineer and repair technician. He seemed to know a lot about the hardware found in Pentax lenses, so we asked him a few questions and also shared our findings from the SDM failure survey.
Below are the questions and answers, all paraphrased from the conversation.

Q: Our survey found that the Pentax DA* 16-50mm and 50-135mm were the most prone to SDM failure. Do you know why this was?
A: One could say that the AF components used in these lenses was prone to failure from the get-go due to their design. The 16-50mm and 50-135mm lenses share the same circuitry and motor, which is why they both have such a high failure rate. Other SDM lenses don't fail as much.

Q: Has this SDM quality control issue been resolved?
A: Yes. The components used in the 16-50mm and 50-135mm lenses have been redesiged, and all lenses produced in 2012 or later should no longer fail.

Q: Why is the DC technology found in the DA 18-135mm so realiable?
A: The DC motor found in the lens is based on the motors used for screwdrive autofocus in Pentax camera bodies, although it's obviously been modified to be quieter and to fit inside the lens.

[aleonx3]

I do have the DA* 16-50 that belongs to the early batches and serial numbers which I can confirm did have problems (not only SDM but slight decentering issue); I bought it used from another user while it was still under warranty. The lens was repaired and has been working since then; I don't think that we heard any more reports of SDM failures in the last while. We can only assume the risk of having SDM failed problem is less with the new batch that you can buy in reputable stores.

Like many others, I like my DA* 16-50 especially for my event/stage photography but I am also tempted to get the DA20-40 for travelling purposes as it is lighter (hopefully my next trip to Japan). I also don't like to use the wide end that much (mostly between 20-40) as my photos usually involves people. I find the 16mm on the wide-end to be little more distortion for my comfort; however, for wide open space in mountains/oceans scenes then they are perfect.

---------- Post added 11-17-2014 at 03:51 PM ----------

"Q: Why is the DC technology found in the DA 18-135mm so realiable?
A: The DC motor found in the lens is based on the motors used for screwdrive autofocus in Pentax camera bodies, although it's obviously been modified to be quieter and to fit inside the lens."

As an analogy, the DC technology is like mounting a motor on conventional bicycle to make it look like a motorcycle? Not a bad idea, at least it saves fuel.

[goubejp]

I have had both, I finally sold the 16-50 to keep a 20-40 + DA 15 combo. My 20-40 copy is sharp at 20 mm - and at all focals. I was horrified by the CA on the 16-50 - though it is possible to correct. And I was fearing SDM issues

[DeadJohn]

... There was that interview with the very friendly German engineer back at Photokina 2012, tho I'm not sure that qualifies as official. ...

I bought my 16-50 new from B&H less than a year ago. Autofocus developed an intermittent problem and the motor was replaced by Precision under warranty. My case is only a single data point but I'm not sure if I was unlucky, got very old stock, or if that 2012 rumor from Germany is false.

[Conqueror]

Might be worth seeing what the 16-85mm brings to the table also

The 20-40mm is a very nice size/weight though