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11-20-2012, 12:49 PM   #16
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QuoteOriginally posted by lytrytyr Quote
The Zeiss ZK lenses come with an inspection slip, signed by an inspector.
Which is part of the reason they're so expensive. People use the terms Quality Control, Quality Assurance and Quality Management as if they mean the same thing, and they don't. If you want zero defects, the only thing that works is 100% inspection (Quality Control) and rejection of any defects. Anything else worthy of a Quality System label requires strict enforcement of process and statistical sampling to validate the defect rate. 100% inspection costs in time (including re-work) and waste. Sampling based Quality Management lowers costs considerably, but means some defective product gets through - that's why manufacturers have warranties.

Of course, that slip is excellent marketing, too.

11-20-2012, 01:10 PM   #17
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QuoteOriginally posted by RobA_Oz Quote
Which is part of the reason they're so expensive.
The ones I bought new were less than USD 1K, in the same range as the 31 and 77 limiteds, or the D FA 100/2.8.

QuoteOriginally posted by RobA_Oz Quote
100% inspection costs in time
It does save the user's time when they don't have the hassle of getting a replacement.
11-20-2012, 11:34 PM   #18
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QuoteOriginally posted by lytrytyr Quote
The Zeiss ZK lenses come with an inspection slip, signed by an inspector.
So did both my copies of the KMZ MC Zenitar 16/2.8, purchased new from Russia. Yes, both my copies. The first was totally non-functional from the factory, despite the signed inspection certificate.


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11-20-2012, 11:45 PM   #19
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QuoteOriginally posted by stevebrot Quote
So did both my copies of the KMZ MC Zenitar 16/2.8, purchased new from Russia. Yes, both my copies. The first was totally non-functional from the factory, despite the signed inspection certificate.
Did you call them on that?

11-20-2012, 11:48 PM   #20
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QuoteOriginally posted by les24preludes Quote
1) Reviews of some samples of the DA 40 and even the 77mm 1.9 have been quite poor.
I want to know more about this as well.

If you are talking about reviews on this site...take them all (mine included) with a grain of salt.

As for your experience with the ST 55/2...there is a lot that can happen to a lens in 40+ years of use and/or storage. I would suspect that your poor example might have been fouled by fungus or perhaps the victim of a poorly executed service. I have two copies of the ST 55/1.8 as well as the Pentax-K 55/1.8 and all three are excellent lenses, both optically and mechanically. Modern QA practices were the rule in the Japanese optical industry in the '60s and into the '70s and quality variation was the exception, not the rule.

A couple of months ago I took delivery of a ST 28/3.5 (first version) that was cosmetically perfect. Strangely, I was unable to get a sharp photo with it. I finally did a careful examination through the rear elements with a bright light and magnifying loupe. Turns out there was both fungus and substantial scour marks on multiple surfaces of the rear-ward elements. The lens had been poorly serviced apparently in an effort to remove fungus and permanently damaged as a result.


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11-21-2012, 12:53 AM   #21
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I forget which lensrental company, but it was one that did a lot of Canon rentals, in any case, a poll of their Canon customers indicated that those customers had higher success rate ordering new Pentax lenses over any other brand.

It seems unrealistic to me to hold Pentax-Ricoh responsible for lens quality of Russian lenses, for example, or Pentax lenses that are over 40 years old and subject to all sorts of abuse. Strange question.
11-21-2012, 01:29 AM   #22
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Here's what I have in terms of lens tests on the 40mm and 77mm:

We should note our sample of the 40mm Limited lens in our tests was slightly soft in the centre when focused at infinity.
Pentax DA 40mm and 70mm Limited lens full review Cameralabs outdoor results


"Interestingly, the DA 40mm f/2.8 Limited, while not the sharpest of the bunch here wide open, doesn't display the same horrific performance that you'll see from it in our field sharpness tests below. To be honest, we're not sure how to account for this disparity. In general, the lens was quite sharp when shooting at close and mid-range distances at wider apertures; when shooting at infinity at the same f-stop, it was abysmal, every time." Scroll down to Comparing Field Sharpness (same physical image size). If you look at the resolution of the road as it goes up into the mountains in the field tests it's quite awful at f2.8, especially compared with the results of the other two lenses tested, which are OK.
Pentax DA 35mm F2.4 vs 40mm XS vs 40mm Limited - Image Quality: Sharpness - PentaxForums.com

User comment: "I am stunned by my K35/3.5. This lens is unbelievably sharp. I have compared it to my DA 40mm F2.8 Ltd., and the K35mm is sharper at every aperture. Perhaps I have a mediocre copy of the DA 40?"

I have some MTF results for the 77mm but I didn't, unfortunately, make a note of where they came from:
f/1.8 55
f/2.8 55
f/4 55
f/5.6 62
f/8 78
f/11 87
f/16 87
f/22 78

In the Photozone tests the edge only reaches "very good" at f4 and concludes "Optically it doesn't offer much beyond the mainstream in this class"
http://www.photozone.de/pentax/128-pentax-smc-fa-77mm-f18-limited-review--test-report?start=1

Last edited by les24preludes; 11-21-2012 at 01:52 AM.
11-21-2012, 02:02 AM   #23
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QuoteOriginally posted by les24preludes Quote
I have some MTF results for the 77mm but I didn't, unfortunately, make a note of where they came from:
f/1.8 55
f/2.8 55
f/4 55
f/5.6 62
f/8 78
f/11 87
f/16 87
f/22 78
Those are not MTF results, but Yoshihiko Takinami's visual tests, on film, from

http://www.takinami.com/yoshihiko/photo/lens_test/pentax_tele.html

11-21-2012, 02:16 AM   #24
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Thanks for that. Any comments on these? The link doesn't seem to work, and I don't speak Japanese.
11-21-2012, 03:16 AM   #25
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QuoteOriginally posted by les24preludes Quote
Thanks for that. Any comments on these?
Since the tests are based on a visual perception of sharpness and contrast on film,
I don't think they're very relevant for digital, with the possibility for adjusting contrast in post-processing.
For example, the M100/2.8 looks poor in Takinami's test,
although it's actually a very sharp lens.

QuoteOriginally posted by les24preludes Quote
The link doesn't seem to work,
Does your browser handle "broken" links,
the way this site presents them?

Anyway, just Google "takinami resolution"

QuoteOriginally posted by les24preludes Quote
and I don't speak Japanese.
The actual pages are in English.
11-21-2012, 12:43 PM   #26
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QuoteOriginally posted by lytrytyr Quote
The ones I bought new were less than USD 1K, in the same range as the 31 and 77 limiteds, or the D FA 100/2.8.
Oh, that they still were in that range, new. I foolishly passed up the ZK 21/2.8 for well under $1k just after CZ announced they weren't continuing to make them for Pentax. Even the Canon/Nikon mount versions are nearly double that, now.

QuoteOriginally posted by lytrytyr Quote
It does save the user's time when they don't have the hassle of getting a replacement.
I doubt that even Leica does 100% inspection for everything, but they may go closer than others. When you're paying first-world skilled wages, it makes for extremely expensive product. Fine for some, but most people shy away from prices like $10k+ for the Summilux 35/1.4 (great lens, I'm sure, but not one most people here would fork out for, even to avoid the possibility of having to send it back for replacement).
11-21-2012, 02:25 PM   #27
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QuoteOriginally posted by philbaum Quote
Strange question.
Agreed...
11-21-2012, 02:40 PM   #28
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QuoteOriginally posted by les24preludes Quote
In the Photozone tests the edge only reaches "very good" at f4 and concludes "Optically it doesn't offer much beyond the mainstream in this class"
I have read the photozone review and have placed empasis in the quote above where it belongs. The class of lens that he refers to is premium portrait-length manual focus lenses. The class includes the best from Canon, Nikon, Zeiss, and others. To complete the quote, " but don't misunderstand this as something negative because moderate fix-focal length tele lenses tend to be great performers."

If there is a persistent issue with the 77 Limited, it is not with quality or with sample variability. The main complaint that people have is with a tendency toward purple-fringing with some subjects. Oh...and there is also the matter of price. $$$


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11-22-2012, 05:53 AM   #29
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QuoteOriginally posted by lytrytyr Quote
The ones I bought new were less than USD 1K, in the same range as the 31 and 77 limiteds, or the D FA 100/2.8.
Quality inspection is just one of the factors influencing the price... So are the lens design, type of glass, the fact that Pentax lenses have that thing called autofocus, and so on...

QuoteOriginally posted by lytrytyr Quote
It does save the user's time when they don't have the hassle of getting a replacement.
User time costs the company nothing.
11-22-2012, 06:13 AM   #30
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QuoteOriginally posted by bdery Quote
Quality inspection is just one of the factors influencing the price... So are the lens design, type of glass, the fact that Pentax lenses have that thing called autofocus, and so on...
The FA Limiteds have screw-drive autofocus without quick-shift,
just like my DA L kit lenses.
And those kit lenses had a negative price,
since body + kit lens was cheaper than body alone.


QuoteOriginally posted by bdery Quote
User time costs the company nothing.
But smart users factor the cost of their own time in to the cost of the lens.
The time taken to arrange a replacement for a bad copy
may be worth a couple of hundred bucks to many users.

Not to all, of course.
If you're not working, you may have time to spare.
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