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09-01-2007, 06:27 PM   #16
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A shame. Hopefully someone will send in a better sample.

I've seen people criticising Klaus before for not always giving totally positive reviews to lenses. Admittedly he does seem to find a lot of centering defects, back or front focus defects, etc. As I see it, he just has very high standards. I don't believe production and quality control can ever be completely 100% perfect... for example we get lenses that have slight focusing defects but normally it's nowhere near significant enough to bother us. Klaus just goes into these specifics in a way many wouldn't bother.

What I really don't understand are conspiracy theorists (not here but on other sites) who are convinced the guy has something against Pentax. Firstly, he is equally picky with other companies' lenses and finds defects in them too. Secondly and perhaps more importantly, if he had something against Pentax and was determined to give bad reviews, why would he even mention defects? Surely he would just publish poor MTF graphs as they are and pronounce it a poor lens? But he mentions it... take a look at the 35mm f/2 review; first time he reviewed it, he said it seemed to have centering defects, and yet gave it a good review saying it "should be" an excellent lens! Doesn't exactly sound anti-Pentax to me. And now he decides not to review a lens which he believes is defective... if it was defective and he reviewed it then it would not be representative of its potential. Personally I'd rather he took this approach than simply publish a poor review.

09-01-2007, 08:21 PM   #17
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QuoteOriginally posted by Tom Lusk Quote
What credibility could you give to a test done by a lens supplied directly from the manufacturer???

Do you think the manufacturer would randomly pick a lens off the production line and ship it off?
Virtually all print magazines test products supplied by the manufacturers (or distributors or dealers). Camera magazines like Popular Photography, car magazines, computer magazines, etc. all rely on evaluation samples supplied by manufacturers or other parties that wish to have the product reviewed in print. The only print magazine that regularly buys its test samples at a retail store is Consumer Reports. And I can't say that I am impressed with their tests of things like cameras and home electronics.

There is always the issue of whether the manufacturer cherry-picked the best sample for testing, or actually tweaks the product for better performance. For example, sometimes the computers tested by a magazine are found to be slightly over-clocked.

And yes, I do think that Klaus is "just some guy on the Internet." I think he is honest and tries to be fair and impartial in his testing, and he does supply some useful information. But there is no testing laboratory with employees and it is obviously a small time operation. Anyone with a camera, a test chart, and a computer can test a lens and produce an chart in Excel of the test results. I wouldn't consider Photozone to be the final word in comprehensive scientific testing of photographic equipment.

And yes, I do think that lenses get dropped in use and mis-aligned. There is a real issue with testing used lenses supplied at random from consumers that you will get a copy that that was dropped and mis-aligned as a result. I recall he mentioned one Canon lens that he had to test 4 samples before he found a good one.

Finally, there is no evidence that the the DA* lenses have "a high percentage of duds." The only evidence of "duds" that I have seen are a few random, anecdotal reports from "some guys on the Internet." To infer from a few reports that "there is a high percentage of duds" is what I would consider "grasping at straws."
09-01-2007, 11:43 PM   #18
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QuoteOriginally posted by GaryML Quote
Finally, there is no evidence that the the DA* lenses have "a high percentage of duds." The only evidence of "duds" that I have seen are a few random, anecdotal reports from "some guys on the Internet." To infer from a few reports that "there is a high percentage of duds" is what I would consider "grasping at straws."
Whether it is straws or a flood, Pentax needs to get on top the issue.
I've used Pentax equipment for close to 40 years. I have very much looked forward to the SMD lens family and happen to own one of those 16-50 pieces of glass which has not been dropped.

I've had some unusual events with it, but I''m a long way from concluding
that it has hopeless problems. Meanwhile there are others who are having issues.

One thing that Pentax does in common with other camera manufacturers
is that they treat their customers very badly. For example little information
is provided about how the product is 'suppose to work' making it very difficult for the customer to determine if his equipment is working as it should.

Presumably the theory is that if the customer doesn't know what the product is suppose to do, he won't know that the product isn't working. In a day of mass ignorace on the part of the consumers this could work.

Now however, there are 'guys on the internet and turkies can't be swept under the rug by PR flaks that deny everything.

The best defense against wild rumors and accusations would be a candid line of communications from Pentax ----

I would be very surprised if there weren't at least some issues with this new product.---there are also likely some workarounds that Pentax knows about but hasn't shared.

there may not be 'herds of duds' on the market--- sheesh! Pentax hasn't even seen fit to tell us how many have been produced.---Herds may not have even be manufactured yet.

Likewise, the allegation that only fumble fingers have purchased the new lens and the reason that many won't work is that every new $1000 lens has been dumped on the floor by its owner is likewise insulting. The idea that an expensive lens which has been on the market for 2 or 3 weeks has already accumulated a vast resovoir of 'dropped lenses' seems to defy credibility as well.

it's time for both sides here to stop flaming and get down to the serious business of sorting out what's smoke and what's fire. and it's time for pentax to break their silence and discuss the issues forthrightly.
09-02-2007, 08:31 AM   #19
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QuoteOriginally posted by rvannatta Quote

Pentax hasn't even seen fit to tell us how many have been produced.---Herds may not have even be manufactured yet.

Likewise, the allegation that only fumble fingers have purchased the new lens and the reason that many won't work is that every new $1000 lens has been dumped on the floor by its owner is likewise insulting.
I've seen sales figures published for SLRs, but I haven't seen any actual sales figures for lenses published by manufacturers. Do Canon, Nikon, Olympus and Sony publish sales figures for interchangeable lenses? I haven't seen such figures published by any manufacturer, although there is often speculation as to the number of copies of a particular lens produced, and retailers can gauge what sells well and what doesn't.

I never said that "every new $1000 lens has been dumped on the floor by its owner." I said that when you test a used lens, there is a possibility that that particular sample has been damaged. With any lens, there is a possibility of a manufacturing defect, or simply sample to sample variations. This is an issue when testing any mass-produced commodity, but it is more of an issue when testing a used item, as it may have been damaged after leaving the manufacturer.

I happen to own a DA* 50-135mm and it works just fine. So far, I have managed to avoid dumping it on the floor. My copy included an instruction book that explains how to use it. It wasn't really necessary but it did explain what was needed to made SDM function, the manual-auto focus switch, how to use the lens hood, etc. I'm not really sure what else you would want Pentax to supply in terms of how "it is supposed to work."

Finally, I have no association with Pentax whatsoever. I don't know what a "PR flak" is, but I have no interest in promoting the Pentax brand. My only point is that anecdotal reports of complaints does not constitute credible evidence of a widespead problems. Perhaps the DA* 16-50 is a poor performer due to poor design, or perhaps many copies have manufacturing defects. I really don't know. But I wouldn't leap to this conclusion based on a handful of posts on Internet discussion groups. Discussion groups like these are full of posts containing rumors, mis-information, and outright FUD.

09-02-2007, 09:00 AM   #20
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QuoteOriginally posted by GaryML Quote
My only point is that anecdotal reports of complaints does not constitute credible evidence of a widespead problems. Perhaps the DA* 16-50 is a poor performer due to poor design, or perhaps many copies have manufacturing defects. I really don't know. But I wouldn't leap to this conclusion based on a handful of posts on Internet discussion groups. Discussion groups like these are full of posts containing rumors, mis-information, and outright FUD.
You are certainly wise to remind us about generalizing based on a handful of reports. However, I am still waiting for someone to post a positive review of the DA*16-50. If I have missed it, I would appreciate it if you directed me to it. It is also possible that those who have had good experiences do not feel as strong a need to give positive feedback as those of us who have had a bad experience. My copy of the lens was awful...no misinformation or rumor there; please see my post comparing it to the Tamron 28-75 for sample photos of poor IQ at f2.8. Until more people get copies and use them, all we can do is attempt to draw conclusions from the information we have. And that information at the moment indicates that there are several poor copies of this lens. I hope there are more excellent copies out there. As a Pentax user I want this lens to be good! My Da* 50-135 is excellent. If I read about people have an issue with theirs I will tell them that my copy is good and that they should try another copy. To date, no one has said that about the DA*16-50. Again, if I have missed something, someone please point me to the review. I want a reason to try another copy of this lens. So far I have not been given a reason to try again.
09-02-2007, 09:35 AM   #21
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QuoteOriginally posted by Wethphotography Quote
I am still waiting for someone to post a positive review of the DA*16-50. If I have missed it, I would appreciate it if you directed me to it. It is also possible that those who have had good experiences do not feel as strong a need to give positive feedback as those of us who have had a bad experience. My copy of the lens was awful...no misinformation or rumor there ....

My Da* 50-135 is excellent.
I have not seen any reviews of the DA* lenses in print. That's not surprising, since they were just released. Popular Photography did publish a review of the Tokina 50-135mm f2.8 and it was quite positive, so that is some information (although the Tokina differs in many respects, especially the lack of SDM). Photozone has a review of the Tokina 16-50mm f2.8 in the Nikon mount, which I'm sure you've read. It will be interesting to see lab tests of the DA* lenses and see how they compare. But , of course, the most important test is how well the lens works for you.

I have read a number of user comments about the DA* lenses in places like dpreview. The opinions of the 16-50mm have been much less favorable than the comments about the 50-135mm. I do recall some people that were happy with their 16-50mm, but others (like you) were unhappy.

I have no reason to doubt that your 16-50mm was a poor performer. But based on this one data point, there is no way of knowing if it was a design defect, manufacturing defect, or shipping damage. If there are manufacturing problems, then they need to recall the product and correct it. If it is simply a bad design, then that would be disappointing but there isn't much they can do about it. But keep in mind that ultra-wide zooms are extremely difficult to design. Add a fast f/2.8 aperture and a zoom ratio exceeding 3X, and you have quite a challenge. A lot of the lenses produced by Canon and Nikon in this range have also turned out to be less than stellar performers.
09-02-2007, 10:05 AM   #22
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QuoteOriginally posted by GaryML Quote
I have not seen any reviews of the DA* lenses in print. That's not surprising, since they were just released. Popular Photography did publish a review of the Tokina 50-135mm f2.8 and it was quite positive, so that is some information (although the Tokina differs in many respects, especially the lack of SDM). Photozone has a review of the Tokina 16-50mm f2.8 in the Nikon mount, which I'm sure you've read. It will be interesting to see lab tests of the DA* lenses and see how they compare. But , of course, the most important test is how well the lens works for you.

I have read a number of user comments about the DA* lenses in places like dpreview. The opinions of the 16-50mm have been much less favorable than the comments about the 50-135mm. I do recall some people that were happy with their 16-50mm, but others (like you) were unhappy.

I have no reason to doubt that your 16-50mm was a poor performer. But based on this one data point, there is no way of knowing if it was a design defect, manufacturing defect, or shipping damage. If there are manufacturing problems, then they need to recall the product and correct it. If it is simply a bad design, then that would be disappointing but there isn't much they can do about it. But keep in mind that ultra-wide zooms are extremely difficult to design. Add a fast f/2.8 aperture and a zoom ratio exceeding 3X, and you have quite a challenge. A lot of the lenses produced by Canon and Nikon in this range have also turned out to be less than stellar performers.
In one of my prev posts the charts to compare the "defective" sample vs the Tokina. The trends are the same and doubt if the Pentax (a good sample) can
be too much better. As an example of a good copy, though the author has some "issues", the optical performance looks rather good. The tree in the distance detail is amazing to me. From looking at the good examples of the Pentax (yes there do seem to be some though probably haven't been through the microscope yet) Pentax concentrated on center sharpness. No mention here of FF or BF or terrible CA, just slightly less than the f4. ect

原野 攝影手* - 手*部落
But back to the show:
Note that it was noted that the Tokina was also "decentered". After going through other brands only the Canon had a low CA figure but of course not perfect. From Klaus'es review. Sigma, Tokina, and Nikon were all pretty much the same.
Regarding the Canon:
The distortion characteristic is quite typical for a zoom lens in this range (pronounced barrel distortions @ 17mm, moderate pincushion distortions @ 55mm) whereas CAs are unusually moderate. Unfortunately vignetting is a weak spot of the lens peaking around 1EV at f/2.8 throughout the range. It's not a show stopper but a little annoying nonetheless.
09-02-2007, 10:13 AM   #23
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The centering defects as someone stated earlier are not limited to just the Pentax models, many reviews even of Canon L glass have had the exact same issue. Generally in this case he will test multiple copies (he tested 4 consecutive copies once of a L series piece of glass and only on the 4th did he achieve a proper test bed). The camera has nothing to do with it really unless the unit itself is defective, he tests all Canon grade lenses with a Rebel 350d to keep the same consistency. There is no perfect lens and as much as QC inspects there's going to be flaws or a bad batch might slip through.

I do agree with Gary in this instance though about testing second-hand products, it's a risky business but I also don't see why the manufacturers aren't providing him test lenses. I used to do some automotive work and companies would ship us out products for review, they'd have a 10 day 'lease' so to speak and if we didn't have the product back in 10 days the company would have to pay the full price of the product. For larger things like superchargers or what not we'd ask for longer periods as install and other things had to be factored in but generally the manufacturers were good with it. Albeit this was a registered publication and photozone seems to be more of a public/personal endeavour even if it is a pretty strong authority for reviews in the photography field.

As for the Canikon glass, I just purchased a 24-105 and a 70-200 f4 and it took me 3 different copies of the 24-105 to find a sharp lens and 2 field tests to get a good 70-200 f4. So yeah, even Canon users have the same problems and we're paying for supposed "Luxury" glass

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