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11-25-2013, 04:52 PM   #1
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DA 40mm: QA issues?

Over the course of the past year or so, I've received a total of 5 DA 40mm lenses as review units, 3 of which seemed to be defective (2 SMC and 1 HD). I observed way more aberrations than there should be, and images were soft from the 3 broken copies. (will post some examples later)

My personal copy which I acquired in 2006 is still working perfectly.

Is this really really bad luck, or have others been experiencing QA issues with the 40mm?


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11-25-2013, 05:31 PM   #2
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I've not had any problems with mine. Like it quite a bit, in fact.
11-25-2013, 08:31 PM   #3
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I experienced QA issue with my DA 21 ltd, the second element had issue.
and the worst thing is that when it came back from Japan after replacing that element, there was a somehow big black dust inside which doesn't need any hunting to see it! so I told them to send it back to clean it's inner elements! I hope it come back better this time :/
11-25-2013, 09:06 PM   #4
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I haven't used mine long but there have been no glaring issues so far.

11-25-2013, 09:32 PM   #5
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My SMC 40 is a crackerjack lens. Super sharp across the frame. Couldn't bee happier with it! Maybe you have a magnetic personality and it's pulling the lenses out of alignment? (ha ha ha!)
11-26-2013, 01:43 AM   #6
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Bad Lens:
View Picture EXIF
Name:  131125_16h.jpg
Views: 227
Size:  142.2 KB

Good Lens:
View Picture EXIF
Name:  131125_17h.jpg
Views: 225
Size:  142.2 KB


Comments? The camera didn't move in between the two shots, so something inside the first lens must be misaligned.

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11-26-2013, 02:19 AM   #7
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QuoteOriginally posted by Adam Quote
Comments?
Aren't you just seeing flare? That is hardly indicative of a lens element alignment problem, maybe just a coating issue.
Shoot a brick wall or something

No problems with mine. A very sharp and predictable performer.
11-26-2013, 06:33 AM   #8
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I bought mine from the marketplace. It was perfect (and gorgeous) on the K20D and K-5. On the K-3 (my copy) it needed some fine AF tuning but it's also magical.

11-26-2013, 08:35 AM   #9
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I bought mine used in the marketplace. It was only a couple of months old. It was pretty good to start but when the cold weather hit a few months later, I noticed the aperture blades were slow and would stick. I sent it in to Eric and he took it apart and cleaned it for a very reasonable price and it's been fine since.
11-26-2013, 11:54 AM   #10
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QuoteOriginally posted by rawr Quote
Aren't you just seeing flare? That is hardly indicative of a lens element alignment problem, maybe just a coating issue. Shoot a brick wall or something
This looks like some sort of internal reflection inside the lens. It's there on both, but the former's is much more pronounced. Same camera angle, same focus, and it happens every time. Both lenses are brand new HD's.

In any case, they're all going back to B&H tomorrow, but I might have time to do a distortion test.

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11-26-2013, 03:23 PM   #11
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Touch wood. So far my 40mm Ltd. has been good. Got it Xmas 2012.
11-26-2013, 04:49 PM - 1 Like   #12
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https://app.box.com/s/jacp1ddqpummv0lk7lm0

The original SMC Pentax -M 1:2.8 40mm on the K-01 iso 400, f/5.6 and 1.3 seconds, camera jpg
A strong street light. The streaks are snowflakes.
11-26-2013, 05:57 PM - 1 Like   #13
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DA 40mm: QA issues?

Does Pentax manufacturer its own glass elements? Regardless, the results are disappointing.

RANT: It really burns my butt that Pentax increased lens pricing AND moved manufacturing from Japan to Vietnam. Japan has a rich history of manufacturing quality products. The result is added value and maybe a better built product.
11-27-2013, 06:28 AM   #14
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QuoteOriginally posted by krebsy75 Quote
Does Pentax manufacturer its own glass elements?
Maybe for one or two specific glass types that they might have developed. But by and large, no. There are a few big manufacturers of glass types in the world : Corning, Schott, Hoya, a few others, and their glass is used by everyone in the optical industry (not only photography).

QuoteOriginally posted by krebsy75 Quote
It really burns my butt that Pentax increased lens pricing AND moved manufacturing from Japan to Vietnam. Japan has a rich history of manufacturing quality products. The result is added value and maybe a better built product.
Japan, China, Vietnam, matters not in the quality of the product. What matters is the manufacturing process, how quality control is put in place, what tests are run, and how the workers are trained and supervised. Not where they are born.

For the record, when Pentax was making lenses in Japan they were manufacturing all those cheap FA zoom lenses not worth their weight. Now that they make their lenses elsewhere there are no dogs in their lineup, and every reviewer on the planet praises the quality of their products.
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