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06-19-2011, 11:21 PM   #1
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Recommended normal-zoom?

hi, this is my second post on the forum. I'm about to transition from Canon and purchase a K-5. I'm attracted to the high-quality prime lenses, but I would also like to have at least one aps-c "normal" zoom for travel. Right now I'm considering the 16-45 f4 ($400), the 17-70 f4 ($480), and the older Tamron 17-50 f2.8 ($460) for purchase. I'm leaning towards either the 16-45 or the Tamron right now. Having the brighter 2.8 would be nice, but I'm feeling like if I buy into a new camera company, I should want their in-house lenses as well (right?). The 16-45 seems to be well-regarded on this forum. But based on specs & zoom range alone, the 17-70 would fit me the best; better build quality, better range, ultrasonic AF. Photozone gave this lens a very good review, but on the Pentax Forums this lens gets a relatively poor rating (7.8/10)... primarily it seems due to AF-errors and SDM-motor failures. To be honest I find this kind of worrying. Is this a lens I should steer clear of? I would appreciate hearing your suggestions, recommendations or any experiences you've had with these lenses. Thanks for your time. Sincerely, Chris

06-19-2011, 11:41 PM   #2
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I won't comment on the image quality of those lenses specifically.
However, I will say a big usability plus in favor of the Pentax DA series of lenses is the quick shift focus and also the little window in the lens hood for turning your circular polarizer. I would really miss these features in third party lenses.
06-19-2011, 11:46 PM   #3
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There's also the Sigma 17-70, 18-50 you may want to look into.

16-45 is well regarded as you said. But I found the range too small. The IQ, image quality will be an upgrade from the kit. I was a bit put off by the SDM failures as well when I considered the 17-70. DC on 18-135 is apparently quieter and more reliable than the SDM.

I actually just placed an order for Tamron 28-75 f2.8. Very favourable reviews on crop bodies. The only lenses I have are DA 70 LTD and 10-17 fisheye so the 28-75 would fit in very well. It's a nice standard range too.
06-20-2011, 12:34 AM   #4
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Look here:
SMC Pentax-DA 17-70mm F4 AL [IF] SDM Serial Numbers - Pentax Serial Number Database -

Actually no one reported problem with DA17-70 in the serial number database. I'm more inclined in primes and already have old FA24-90 as normal zoom, but being worried about SDM is just plain stupid.
In last 3 years the number of failures is no bigger than the failure percentage with Canon USM or with Nikon whatever. There are failures, but that is usual with in-lens motor. Pentax users were used to have indestructible FA screw drive lenses and the problem is terribly exaggerated.

06-20-2011, 02:01 AM   #5
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I use the Tamron 17-50 2.8... Stunning IQ... Sharp... Serious looking piece of glass...
06-20-2011, 05:07 AM   #6
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QuoteOriginally posted by DaveHolmes Quote
I use the Tamron 17-50 2.8... Stunning IQ... Sharp... Serious looking piece of glass...
I second this. I also question your quoted price on the 16-45. Too high. US$240 would be more accurate.
06-20-2011, 05:10 AM   #7
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I'm in a similar boat, considering what to get to replace my kit lens. Thanks for starting this thread and I'll follow it with interest.

FWIW, I'm leaning toward the Tamron because of the f2.8. Nice to see the positive comments as well!
06-21-2011, 07:18 PM   #8
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QuoteOriginally posted by cp_oaktown Quote
Right now I'm considering the 16-45 f4 ($400), the 17-70 f4 ($480), and the older Tamron 17-50 f2.8 ($460) for purchase.
Welcome to Pentax and the K5. Based on the reviews the 16-45 and 17-50, which I do not have, appear to be excellent choices. I actually have the DA 17-70, and like it a lot, so I can recommend it from personal experience. I feel that one does not have to steer clear of the DA 17-70. I bought mine used here for a good price. I replaced the Pentax 18-55 II, and I consider the upgrade to be worth it, though I had been pleased with the 18-55 II. I have been a bit saddened by the scores the 17-70 has received here, but almost all other professional and consumer reviews were favorable. I've had the 17-70 for about 9 months, and the SDM has been good. However, there have been a few, rare, times that the focus could not lock on. Others have reported this (if it is the same thing I'm experiencing) and seem to be very bothered by this aspect. This is not a concern to me at all as the frequency is rare, and I can work around it quickly. My older body, K100d Super, might also be part of the rare focus lock problem, though for the vast majority of time the focus is fast and accurate. When I chose the 17-70 I was somewhat more influenced by the Photozone reviews showing little quality difference in the common range between the 16-45 and the 17-70. I wanted the most desirable normal zoom lens in the Pentax lineup. As for the Tamron 17-50, a number of reviewers stated that the lens was phenomental once focus was adjusted for with an in-camera focus adjustment, which I did not have with the K100dS, so I reluctantly took that nice lens off my shopping list. As for the 17-70 score of 7.8 here, my experience is that the lens is much better than that. The lens is better than the 18-55 II. It is also spec'd and professionally tested better than the 16-45, so I believe the score of 7.8 here is a data point outlier.

Hope this helps.




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