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05-04-2009, 08:35 PM   #1
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Possible 16-50 DA* Decentering

I bought a 16-50 DA* from Amazon.com last week, while I was initially very happy with it I kept noticing a distinct lack of sharpness in the corners. As a result, I set aside some time this evening to do the newspaper test.

At all focal lengths the lower right hand corner was never quite as sharp as the rest of the pictures, and not until f/8 did the lower right hand corner come close to matching the sharpness of the rest of the image.

I've uploaded f/4, f/5.6, and f/8 examples to Flicker at 16mm, 21mm, 29mm, 36mm, and 50mm. 16-50 Decentering Test - a set on Flickr

Can I live with the softness in the lower right hand corner? Probably. Do I want to put up with it considering how much the lens cost? Not really.

So is my 16-50 suffering from decentering issues or I am being too picky?

05-04-2009, 09:54 PM   #2
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I have had a look at most of the pics.... seems soft in most corners. But, the newspaper is also not completely flat. I would re-test with very flat paper and cross test against another lens (both off the same tripod). But essentially I agree that if a DA* lens is not spot on then it should be replaced. BTW, must be harder for lens makers in the digital age. It cost us nothing to snap off hundreds of test shots and review on a monitor..... can't see many people doing that with film.

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05-04-2009, 11:00 PM   #3
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I don't think you are being too picky. I think it is decentered. Especially considering the shots are taken with the aperture stopped down. I agree that it doesn't improve until f8.

I went through 3 of these lenses before giving up. My lenses had worse decentering than yours. Don't let people tell you "just go out and take pictures." That is like buying a brand new Mercedes with a cylinder misfiring and people telling you to: "Just go out and drive." You spent a premium for that lens, so you have the right to expect it to perform at a level commensurate with its cost.

If you want a lens that is sharp edge to edge, get the Tamron 17-50 (see photozone.de tests if you don't believe me). If you must have a lens you can use while taking a shower, and can live with soft edges, wicked mustache distortion at 16mm, and potential SDM problems, I guess you have no choice but the DA*.

Last edited by PentaxPoke; 05-04-2009 at 11:32 PM.
05-04-2009, 11:24 PM   #4
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QuoteQuote:
Pentax Poke: If you want a lens that is sharp edge to edge, get the Tamron 17-50 (see photozone.de tests if you don't believe me).
Yes, my Tamron is shaaaaaaaaaaaaaarp to the edges too. Beautiful lens!

QuoteQuote:
Pentax Poke: If you must have a lens you can use while taking a shower, and can live with soft edges, and potential SDM problems, I guess you have no choice but the DA*.
You can take a shower with your Tammy too, but visit this thread first.

https://www.pentaxforums.com/forums/field-accessories/59144-weather-proof-your-lens.html


05-04-2009, 11:30 PM   #5
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QuoteOriginally posted by Jewelltrail Quote
Yes, my Tamron is shaaaaaaaaaaaaaarp to the edges too. Beautiful lens!



You can take a shower with your Tammy too, but visit this thread first.

https://www.pentaxforums.com/forums/field-accessories/59144-weather-proof-your-lens.html
I forgot about that post. Yes that settles it and eliminates the only advantage of the 16-50. There is now absolutely no reason whatsoever to buy the DA* 16-50!
05-04-2009, 11:43 PM   #6
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QuoteOriginally posted by Jewelltrail Quote
Yes, my Tamron is shaaaaaaaaaaaaaarp to the edges too. Beautiful lens!



You can take a shower with your Tammy too, but visit this thread first.

https://www.pentaxforums.com/forums/field-accessories/59144-weather-proof-your-lens.html
It would be great to have a wide-short telephoto zoom lens that doesn't extend to suck in air.
05-04-2009, 11:56 PM   #7
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QuoteOriginally posted by asdf Quote
It would be great to have a wide-short telephoto zoom lens that doesn't extend to suck in air.
Agreed. The Tamron has a single telescoping stage, whereas the DA* 16-50 has a 2-stage telescoping system, which to me seems more complicated, and provides more sources for dust to enter. (I know the DA*'s are supposed to be "sealed" but I certainly don't think they are airtight otherwise you would feel the vacuum drawn when the lens extends.)
05-05-2009, 12:05 AM   #8
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When I did all the research on the Tammy 17-50 vs the Da 16-50 and came away knowing I was about to own the Tamron, one troublesome thought was with me--I love to hike in NE mountains, year round, and the Tammy is not weather sealed.

However, I have now hiked for over a year with the Tammy and am no longer as concerned about the weather sealing feature. Hikes like this one here https://www.pentaxforums.com/forums/post-your-photos/45963-winter-hike.html have shown me the Tamron, weather sealed or not, can handle the extremes of New England weather, even above timberline.

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