[Loren E]

The 16-50 specs out as the perfect lens for me with the 60-250......but I want to be making a long term investment with glass not a short one! Torn.... :/

[Ash]

I just see no need to hold back from getting the lenses that suit your needs to a tee because of any inherent AF problems when they can be rectified in repair under warranty. If the ongoing cost of warranty is an issue, then it would probably mean that the lenses would also be beyond your budget, but I get the impression that cost is not the issue at all. In this regard, there may well be a 'risk' involved, but the only inconvenience you'll have to put up with is that of the lens not being available to you for use whilst it is being repaired, however infrequent this may be.

[Loren E]

I am not worried about paying for the cost of warranty (small compared to the daunting cost of the lenses for me), though reviews of Mack warranty seem pretty mixed with some horror stories.

My issue is as a travel photographer going on remote fly fishing trips, it would really be a trip ruiner to have the AF go out. For example I'll be in Belize for 2 weeks in June on a remote island. I can likely make some decent money on the shots from this trip, but if the 16-50 were to crap out on the first day I'd be out of luck except for tele work with the 60-250. Even if manual focus is still working, lots of times I am fly fishing alone and setup my camera on a tripod with self timer and then get infront for the glory shoot hoisting up a big fish with before release....manual focus would do me little good. I suppose I could pony up $100 for a cheap backup like the 18-55 WR but I really want to keep spending to a minimum and although I am willing to pay good money for quality glass, I don't like the idea of having to spend another 3 digits on a poor glass for backup.

It feels extremely difficult to get an accurate idea of the reliability of this lens from the boards. On one end of the spectrum it is easy to think they are ticking time bombs that will break whether it be after a week or after 2 years, but certainly long before they should (5-10 years IMHO). On the other end of the spectrum you have people posting on the boards with problems and lots in the real world who have no problems and so don't come to voice a problem, and in reality the issues have largely been gotten under control and failure rates are now in line with any other AF lens from another manufacturer. Even though I think it is not smart and unethical, it makes sense that Pentax would not acknowledge the issue, but it does not make sense that behind the scenes they wouldn't get some engineers to rework the design and get it up to speed.

If I go for it Ash, would you recommend buying a brand new one for $750 + 7 year mack warranty, or getting a used one that has shown no signs of SDM and was bought recently + 2 year mack warranty? It comes down to $200 - $250 of a difference.

[Loren E]

By the way you said "inherent AF problems"....so does this mean you think AF problems are inevitable with this lens? (not talking about in many many years)

[dgaies]

I just see no need to hold back from getting the lenses that suit your needs to a tee because of any inherent AF problems when they can be rectified in repair under warranty.

By the way you said "inherent AF problems"....so does this mean you think AF problems are inevitable with this lens? (not talking about in many many years)

I believe what Ash meant is that if a particular lens suits your needs extremely well because it has your desired focal length range, has outstanding IQ and is weather sealed, you shouldn't necessarily pass on it just because it may have problems later that can easily be addressed under warranty.

As to whether AF problems are inevitable, the answer is no, it's not inevitable in the sense that many people own SDM lenses and never have a single issue. It is, however, much more likely that you'll have an AF failure with a DA* lens compared to a more conventional screw driven lens. The exact amount of risk is unknown, but my personal opinion is that if you want a DA* lens, buy it, and just be aware that you may have to have it serviced at some point if there is an issue. If you don't want to deal with the potential for failure, then I would advice staying away from DA* lenses as that's the only guaranteed way to avoid an SDM failure.

[twitch]

My issue is as a travel photographer going on remote fly fishing trips, it would really be a trip ruiner to have the AF go out. For example I'll be in Belize for 2 weeks in June on a remote island. I can likely make some decent money on the shots from this trip, but if the 16-50 were to crap out on the first day I'd be out of luck except for tele work with the 60-250.

You'd never want to be in the situation where you were totally reliant for doing a pro job on the 16-50. You'd pack another lens; eg a 18-55 WR if WR is important, otherwise a DA16-45.

[Ash]

I believe what Ash meant is that if a particular lens suits your needs extremely well because it has your desired focal length range, has outstanding IQ and is weather sealed, you shouldn't necessarily pass on it just because it may have problems later that can easily be addressed under warranty.

As to whether AF problems are inevitable, the answer is no, it's not inevitable in the sense that many people own SDM lenses and never have a single issue. It is, however, much more likely that you'll have an AF failure with a DA* lens compared to a more conventional screw driven lens. The exact amount of risk is unknown, but my personal opinion is that if you want a DA* lens, buy it, and just be aware that you may have to have it serviced at some point if there is an issue. If you don't want to deal with the potential for failure, then I would advice staying away from DA* lenses as that's the only guaranteed way to avoid an SDM failure.

Right, and there never will be any way of knowing which lenses will and will not develop an SDM problem. It is also impossible to attest to the their longevity given none of the lenses have reached even a 10 year milestone yet. But it's plausible to consider the screwdrive AF lenses as being more of the kind that can pass through from generation to generation and never lose value whereas the DA*s are yet to prove this.

Nevertheless, as I keep saying, you can hardly find an optically more brilliant set of zooms than the DA*s, and for outdoor conditions these lenses are best. As to new/used - to me it doesn't matter, as long as the warranty goes on for as long as possible. 2 years may or may not be enough - hard to say. If you could get a used lens with 7 years warranty, that would be the way to go IMO.

[Loren E]

You'd never want to be in the situation where you were totally reliant for doing a pro job on the 16-50. You'd pack another lens; eg a 18-55 WR if WR is important, otherwise a DA16-45.

And is this very SDM specific? I.E. if you were a canon shooter with an L series lens would you not worry about a backup?

[Loren E]

Thanks for the input all. Gosh I couldn't care less about silent focusing either, I wish I could have these lenses just with screw drive....and it would be cheaper that way too! Just goes to show you new technology is often not better technology...

[dgaies]

And is this very SDM specific? I.E. if you were a canon shooter with an L series lens would you not worry about a backup?

I would answer that it's not SDM specific. Forget about AF motor failure, what if you drop the camera or turn quckly and bang the lens against something. Gravity doesn't care if Pentax or Canon is written on the outside of the lens

If what you are really asking is are SDM lenses more prone to failure than Canon L series USM lenses, the answer is probably yes (although without actual data sets it's impossible to fully quantify it). But the fact is that a Canon USM motors can fail, and even if it's substantally less often, a professional photographer being paid for their work would want/need a backup plan regardless.

[Ash]

Only issue with going with screwdrive WR lenses is that thus far the lenses that offer this are of modest quality optically. If WR is not totally necessary for you (taking due care on the boat) but IQ is, then why not go with Tamron 17-50 or Tamron 28-75 coupled with the Tamron 70-200 plus Tamron 1.4x TC - two lenses that effectively cover most of the useful focal lengths. Otherwise, there's no choice but to go with the DA*s and strongly consider the warranty.

[dgaies]

Only issue with going with screwdrive WR lenses is that thus far the lenses that offer this are of modest quality optically. If WR is not totally necessary for you (taking due care on the boat) but IQ is, then why not go with Tamron 17-50 or Tamron 28-75 coupled with the Tamron 70-200 plus Tamron 1.4x TC - two lenses that effectively cover most of the useful focal lengths.

Although not WR, the Tamron 28-75 + 70-200 + 1.4x is just about as much bang for the buck as you can get (~$1000 used). FWIW, the Tamron 1.4x works really well with the 70-200, something I can't say about the 60-250+1.4x.

[ve2vfd]

FWIW, the Tamron 1.4x works really well with the 70-200, something I can't say about the 60-250+1.4x.

I just tried my Tamron 1.4 TC on the DA*60-250 and it works (of course low light indoor = lots of hunting on the K20d)

Pat

[Loren E]

Weather sealing is a really high priority for me, hence my attraction to Pentax because it seems like it makes the best sealed system out there. I think I'm going to have to pull the trigger, I just want a solid 3 years without trouble and I will be very pleased. I won't know if I'll get that until I try I suppose. Shame on Pentax Japan headquarters. Well thanks for the advice all, I appreciate it hugely being so much less experienced.

[dgaies]

I just tried my Tamron 1.4 TC on the DA*60-250 and it works (of course low light indoor = lots of hunting on the K20d)

Pat

I didn't mean to imply it didn't work with the 60-250, which it does. I just meant the combo with the 70-200 works better in terms of AF performance.